Practical answers about GAZDA and Galan electrode boilers: how they work, how to choose the right power, what water conductivity is required, how to connect controllers, and how to use the boiler safely.
Boiler models, availability and prices
Electrical Connection
Water Conductivity
Boiler Power & Consumption
Installation
Troubleshooting
Delivery & Support
What is the difference between Galan, GAZDA, Geyser and Volcano boilers? Galan and GAZDA are two different brands of electrode boilers. Geyser and Volcano are product series made under the Galan brand, not separate brands. All these boilers operate on the same basic principle: alternating electric current passes through the heating fluid between the electrodes, and the fluid heats up due to its own electrical resistance. Unlike a conventional electric boiler with heating elements, an electrode boiler does not use a separate tubular heating element. Geyser is a series of medium-power three-phase Galan boilers. Volcano is a series of higher-power three-phase Galan boilers designed for larger buildings and heating systems with a greater volume of heating fluid. GAZDA is a separate brand of electrode boilers that includes single-phase and three-phase models with different designs and power ratings. The main differences are therefore not in the heating principle, but in the construction, power output, supply voltage, connection sizes, compatibility with electrical protection devices, and control options. For this reason, individual boiler models and their technical specifications should be compared rather than brand names alone.
Where can I find the wiring diagram or installation manual for a GAZDA boiler? Installation manuals and technical information for GAZDA boilers are available on the GAZDA page of our website. There you can find documentation for the different boiler series, including model-specific installation and operating instructions. Electrical wiring diagrams are available separately in the Documentation section under “Electrical Circuit Diagrams.” This section contains connection diagrams for GAZDA boilers, controllers, thermostats and other system components. Before using any document, check the exact boiler model and select the corresponding manual or wiring diagram. Electrical installation should be carried out by a qualified electrician in accordance with the correct diagram for the specific model.
What is the price of a GAZDA or Volcano boiler and how much does delivery cost? The price depends on the boiler model, power rating and selected configuration. The current price is shown on the relevant GAZDA product page in our online store. Delivery cost is calculated separately and depends on the destination country, parcel weight and package size. In most cases, the exact shipping cost is displayed during checkout after entering the delivery address. If the cost is not calculated automatically, it can be confirmed before purchase.
Which boiler power ratings are currently available? The GAZDA range includes single-phase and three-phase electrode boilers in different power ratings. Single-phase 230 V models are available in 2, 4, 6 and 8 kW versions. Three-phase 400 V models are available in 3, 6, 9, 12, 15, 18, 25, 36 and 50 kW versions. Availability may vary depending on the product series and current stock. The latest models and configuration options are listed on the GAZDA page and individual product pages.
Where are the boilers produced and who is the manufacturer? GAZDA boilers are manufactured in Poland by Yan Benchak JDG, a Polish company responsible for the development, assembly and sale of GAZDA electrode boilers. The boiler body and accompanying documentation include the brand name, model designation, main technical specifications and manufacturer details. For the most accurate information about a specific boiler, check the product label, installation manual and relevant product page.
What is included in the boiler set and do I need to buy additional components? The contents of the set depend on the selected boiler model and configuration. The basic set usually includes the GAZDA boiler itself. Extended configurations may also include a thermostat, control unit or other components listed on the relevant product page. A complete heating system normally requires additional components such as a circulation pump, expansion vessel, safety group, filter, shut-off valves, pipes, electrical protection devices and a suitable control system. The exact contents of each set are always specified in the product description. Before purchasing, check which components are included and which must be purchased separately for your particular heating system.
Can I use a single-phase 230 V connection instead of a three-phase 400 V connection? Yes. Any three-phase GAZDA electrode boiler can technically be connected to a single-phase 230 V supply. With this type of connection, the same phase is supplied to all three electrodes. In 36 kW and 50 kW models, the phase is supplied to all six electrodes. The neutral conductor is connected to the boiler body in accordance with the correct wiring diagram. For example, a 9 kW three-phase boiler has three electrode circuits rated at approximately 3 kW each. When all three electrodes are connected to the same phase, the total power can reach 9 kW and the current at 230 V will be approximately 39 A. A 15 kW boiler would draw approximately 65 A, while a 25 kW boiler would draw approximately 109 A. Therefore, even high-power three-phase models can technically operate on 230 V, but in practice boilers above 9 kW are rarely connected to a single-phase supply because of the very high current demand. The actual power of an electrode boiler also depends on the temperature and electrical conductivity of the heating fluid. Installation must be carried out by a qualified electrician, taking into account the available electrical capacity, cable cross-section and protective-device ratings.
What circuit breaker do I need for a specific boiler power? The circuit breaker should be selected according to the boiler’s nominal current, using the next higher standard breaker rating. For a single-phase 230 V connection: 2 kW — approximately 9 A, use a 10–16 A circuit breaker 4 kW — approximately 17 A, use a 20 A circuit breaker 6 kW — approximately 26 A, use a 32 A circuit breaker 8 kW — approximately 35 A, use a 40 A circuit breaker 9 kW — approximately 39 A, use a 40–50 A circuit breaker 15 kW — approximately 65 A, use an 80 A circuit breaker 25 kW — approximately 109 A, use a 125 A circuit breaker For a three-phase 400 V connection: 3 kW — approximately 4 A per phase, use a 6 A circuit breaker 6 kW — approximately 9 A per phase, use a 10 A circuit breaker 9 kW — approximately 13 A per phase, use a 16 A circuit breaker 12 kW — approximately 17 A per phase, use a 20 A circuit breaker 15 kW — approximately 22 A per phase, use a 25 A circuit breaker 18 kW — approximately 26 A per phase, use a 32 A circuit breaker 25 kW — approximately 36 A per phase, use a 40 A circuit breaker 36 kW — approximately 52 A per phase, use a 63 A circuit breaker 50 kW — approximately 72 A per phase, use an 80 A circuit breaker The nominal power of a GAZDA boiler is specified for a heating fluid with an electrical conductivity of approximately 200 µS/cm under normal operating conditions. If the conductivity of the water is higher, the boiler may draw more current and produce more than its nominal power. In this situation, a circuit breaker selected exactly for the nominal current may trip periodically. For this reason, the next higher standard circuit-breaker rating is normally selected, but only when the cable cross-section, installation method and electrical supply are suitable for that current. A circuit breaker primarily protects the cable and electrical wiring, so a higher-rated breaker must not be installed without verification by a qualified electrician.
Can the boiler be connected through an RCD and what type of RCD is required? GAZDA KE and GM single-phase boilers, as well as R three-phase boilers, can be connected through an RCD. The design of these models allows them to operate with residual-current protection when the electrical connection is made correctly. For additional protection against electric shock, a Type A RCD with a rated residual operating current of 30 mA is recommended. A two-pole RCD is used for a 230 V single-phase connection, while a four-pole RCD is used for a 400 V three-phase connection. The rated current of the RCD, for example 25 A, 40 A, 63 A or 80 A, must not be lower than the rating of the circuit breaker protecting the same circuit. A 30 mA RCD protects against dangerous leakage current, but it does not replace the circuit breaker, which protects the cable against overload and short circuit. All live conductors of the same circuit — the phase or all three phases, together with the neutral conductor — must pass through the same RCD. The boiler neutral must not be connected to a different neutral bar or to a circuit protected by another RCD, as this will cause the protection to trip. Standard GAZDA BE boilers are not designed for connection through an RCD because the neutral and protective conductors are connected to the metal boiler body. Neutral and protective earth must not be joined downstream of an RCD. A BE boiler must not be connected through an RCD simply by disconnecting the protective earth or by attempting to insulate the boiler body without a proper design. Any non-standard solution involving a separate protective enclosure, electrical insulation and plastic pipe sections must be individually designed and verified by a qualified specialist. It is not part of the standard boiler installation.
Why does the RCD trip immediately after switching on the boiler? Immediate RCD tripping means that a residual current is present: part of the current is not returning through the neutral conductor that passes through the same RCD. The cause may be the boiler itself, the wiring arrangement or another component in the heating system. The most likely causes should be checked in the following order. The boiler is not compatible with an RCD GAZDA BE boilers, Galan boilers and similar electrode boilers with a metal body connected to both neutral and protective earth are not designed for standard connection through an RCD. In this type of installation, part of the current may flow through the boiler body and the PE conductor, causing the RCD to trip immediately after the boiler is switched on. The boiler is connected to the wrong neutral conductor If the boiler is an RCD-compatible GAZDA KE, R or GM model, the most common cause is an incorrect neutral connection. The phase, or all three phases, and the boiler neutral must come from the same RCD. The neutral must not be taken from another neutral bar, from a point before the RCD, from another RCD or from a different electrical circuit. For testing, a qualified electrician can temporarily connect the compatible boiler directly to the output of the relevant RCD, using the phase and neutral from that RCD and bypassing thermostats, pumps and other equipment. If the RCD does not trip with this direct connection, the fault is in the existing wiring or one of the connected components rather than in the boiler. The leakage is caused by other equipment If the boiler is compatible with an RCD and is connected to the correct neutral, the circulation pump, thermostat, contactor, control unit, cables and electrical connections should be checked separately. Possible causes include damaged insulation, moisture, an incorrect N-PE connection or leakage current from one of the connected devices. This cause is less common, but it must still be ruled out. Do not disconnect the protective earth, join N and PE downstream of the RCD, or install an RCD with a higher residual-current rating simply to prevent tripping. Testing and temporary direct connection must be carried out by a qualified electrician.
Do I need a project and who should install the boiler? When designing a new heating system or carrying out a major reconstruction of an existing system, two separate parts of the project are normally considered: the hydraulic design and the electrical design. The hydraulic design specifies the boiler location, pipe layout, pipe diameters, radiators or underfloor heating circuits, circulation pump, expansion vessel, safety group, filters, shut-off valves and other components of the heating system. The electrical design specifies the boiler connection method, supply voltage, cable cross-section, circuit breaker, contactor and RCD ratings, as well as the requirements for protective earthing and the electrical distribution board. For a simple boiler replacement in an existing and correctly designed system, a separate project may not be necessary. However, for a new installation, an increase in available electrical power, changes to the wiring, or the installation of a high-power three-phase boiler, a technical calculation and project documentation are strongly recommended and may be required by local regulations. The hydraulic installation should be carried out by a heating-system specialist or qualified installer. The electrical connection of the boiler and protective devices should be carried out by a qualified electrician.
What liquid should be used in the heating system: tap water, glycol or antifreeze? For GAZDA boilers, the simplest and recommended heating fluid is ordinary tap water with an electrical conductivity of approximately 200–300 µS/cm at around 20°C. At this conductivity, the boiler can develop power close to its nominal rating. Distilled or demineralised water can also be used, but its initial electrical conductivity is close to zero. It therefore has very high electrical resistance, and an electrode boiler will initially draw almost no current and produce very little heat. After filling the system, the conductivity of distilled water must be gradually increased to the required level. This is done by adding very small amounts of salt solution while continuously monitoring the conductivity with a conductivity meter and checking the boiler current. A large amount of salt must never be added at once, because the conductivity may increase sharply and cause the boiler to draw excessive current. Standard ready-made antifreeze or heating fluid sold in building-supply stores and intended for gas, solid-fuel or conventional electric boilers is usually unsuitable for an electrode boiler. These fluids often contain salts and additives that make their electrical conductivity many times higher than required. When such a fluid is used, the boiler current can rise very quickly, causing the circuit breaker to trip after only a few seconds because of overcurrent. This is not an RCD issue: the circuit breaker disconnects the supply because the current is too high. A heating fluid based on ethylene glycol or propylene glycol may theoretically be used if its electrical conductivity at the final working concentration is suitable for an electrode boiler. However, a product should not be selected only because its label says that it is intended for heating systems. Its conductivity must be measured before the system is filled. Where reliable frost protection is required, a practical solution is to use two separate circuits connected through a heat exchanger. The small circuit connected directly to the boiler is filled with water adjusted to 200–300 µS/cm. The larger circuit containing radiators or underfloor heating can be filled with a suitable antifreeze because this fluid does not come into contact with the boiler electrodes. Such a system normally requires a heat exchanger and at least two circulation pumps, one for each circuit. This makes the installation more complex, but it allows the electrode boiler to operate correctly while protecting the main heating system against freezing. After filling the system, both the conductivity of the cold heating fluid and the actual boiler current should be checked. Electrical conductivity and current increase as the fluid heats up. As a practical guideline, when a correctly prepared heating fluid is heated from approximately 20°C to 65–70°C, the boiler current usually increases by about 2.5 times. For example, a three-phase 9 kW boiler draws approximately 13–14 A per phase at operating temperature. With the heating fluid at around 20°C, the current should normally be approximately 5–6 A per phase. This allows the expected operating current to be estimated without waiting for the entire system to reach full temperature. For example, if the ammeter shows 6 A with cold fluid, approximately 15 A can be expected after heating. The 2.5 factor is an approximate practical value. The actual increase depends on the composition, initial conductivity and temperature of the heating fluid. Final adjustment should therefore be confirmed by measuring the real boiler current at operating temperature.
What is the optimal water conductivity for an electrode boiler? The optimal conductivity of the heating fluid for GAZDA boilers is approximately 200–300 µS/cm at around 20°C. With water in this range, the boiler will usually develop power close to its nominal rating. The system can be checked in two ways: with a conductivity meter or with an ammeter. A conductivity meter directly measures the electrical conductivity of the water. An ammeter shows the boiler’s actual current and is often more useful in practice because it allows the real power to be assessed at the existing supply voltage, water temperature and electrode configuration. At a heating-fluid temperature of around 20°C, the current is normally about 2.5 times lower than at an operating temperature of 65–70°C. For example, if the boiler draws 6 A with cold water, approximately 15 A can be expected after the system heats up. If the current or power does not match the required value, the boiler can be adjusted in two ways. The first method is chemical adjustment of the heating fluid. If the conductivity is too high, part of the water can be replaced with distilled or demineralised water. If the conductivity is too low, small amounts of a prepared salt solution can be added gradually. After each addition, the heating fluid must be allowed to circulate and mix completely before the current is measured again. A large amount of salt must never be added at once. The second method is mechanical adjustment of the active electrode surface. If the boiler draws too much current, the electrode can be shortened or part of its surface can be covered with heat-shrink tubing. This reduces the contact area between the electrode and the water, thereby lowering the current and boiler power. Power can be increased mechanically only by installing a longer electrode, provided that this is permitted by the boiler design and body length. An existing electrode should not simply be extended by attaching an additional metal section. Mechanical adjustment does not change the conductivity of the water. It changes only the active contact area between the electrode and the heating fluid and therefore changes the operating current. Final adjustment is best carried out using an ammeter at a known supply voltage and water temperature. For a three-phase boiler, the current should be checked on every phase. The operating current must correspond to the required boiler power and must not exceed the permitted ratings of the cable, circuit breaker and other system components.
Can automotive antifreeze such as Borygo be used in the heating system? Automotive antifreeze, including products such as Borygo, should not be used directly in the circuit of a GAZDA electrode boiler. These fluids are designed for automotive cooling systems and contain glycol, salts, corrosion inhibitors and other additives. Their electrical conductivity is usually 10–15 times higher than the level required for normal operation of an electrode boiler. If the boiler circuit is filled with automotive antifreeze, the current can rise above the permitted value very quickly. As a result, the circuit breaker may trip after only a few seconds because of overcurrent. This is not an RCD issue: the power is disconnected because the operating current is too high. A fluid cannot be considered suitable only because it is based on ethylene glycol or propylene glycol. Before use, the conductivity of the final mixture must be measured and confirmed as suitable for an electrode boiler. Most automotive antifreezes do not meet this requirement. Where frost protection is required, a two-circuit system with a heat exchanger is recommended. The small boiler circuit is filled with water adjusted to 200–300 µS/cm, while the main circuit with radiators or underfloor heating can use a suitable antifreeze because it does not come into contact with the boiler electrodes.
What should I do if the water conductivity is too low or too high? If the water conductivity is lower than recommended, the boiler will draw less current and produce less power. This is not a fault. If the boiler still heats the building to the required temperature and its performance is satisfactory, nothing needs to be changed. Lower power simply means slower heating and longer operating cycles. If more power is required, the conductivity can be increased gradually by adding small amounts of a prepared salt solution. After each addition, allow the heating fluid to circulate and mix completely, then check the current with an ammeter or measure the conductivity with a conductivity meter. Do not add a large amount of salt at once. If the conductivity is higher than recommended, the boiler will draw more current and produce higher power. A moderate increase is not necessarily a problem, provided that the current remains within the permitted limits, the circuit breaker does not trip, and the cable, contactor and other electrical components are correctly rated for the load. If the current is too high, the circuit breaker trips or electrical components begin to overheat, the conductivity should be reduced. Drain part of the heating fluid and replace it with distilled or demineralised water. Allow the system to mix fully and then check the current again. High current can also be reduced mechanically by shortening the electrode or covering part of its surface with heat-shrink tubing. This reduces the active contact area between the electrode and the water and therefore lowers the boiler power. It is important to distinguish between boiler power and actual energy consumption. For example, if a 9 kW boiler is operating at 10 or 11 kW, this does not automatically mean that daily or monthly electricity consumption will increase by the same proportion. With the same building heat loss and the same target temperature, a more powerful boiler will usually heat the system faster and switch off sooner. Final adjustment should be based on the actual boiler current at a known supply voltage and water temperature. For a three-phase boiler, the current should be checked on every phase.
Does the heating system need to be cleaned before installing an electrode boiler? Yes. An existing heating system should be flushed before installing an electrode boiler, especially if it has previously operated with another boiler or with old heating fluid. The pipes and radiators may contain rust, sludge, scale, sealant residues and chemical additives. These contaminants can change the electrical conductivity of the water, cause unstable boiler current, clog the filter or circulation pump, and reduce heating-fluid circulation. The system should be flushed until the drained water is clean. If a chemical flushing agent has been used, it must be removed completely, and the system should then be rinsed several times with clean water. Residual chemicals can significantly increase conductivity and cause excessive boiler current. After flushing, the strainer should be cleaned or installed, the system should be filled with suitable water, and the boiler current should be checked with an ammeter. Any conductivity adjustment should be made only after the heating fluid has circulated and mixed completely. For a new and clean installation, intensive chemical flushing is usually unnecessary, but installation debris, metal shavings, flux residues and other contaminants should still be removed before commissioning.
How quickly does the boiler heat water from 20°C to 60°C? In a real heating system, this question cannot be answered with one exact time because the boiler does not heat water in an insulated container. The heated fluid immediately flows through the radiators or underfloor heating and begins transferring heat to the building. The heating time therefore depends not only on the water volume and boiler power, but also on the building’s heat loss, room temperature, radiator size and temperature, circulation rate, pipe length and the initial temperature of the entire system. If only theoretical water heating is considered, without radiators and without heat loss, the time can be calculated from the water volume, temperature difference and boiler power. A water-heating calculator is available in the Calculators section of our website, where you can enter the initial temperature, final temperature, water volume and boiler power. In an operating heating system, the actual result will always be different because the radiators begin releasing heat immediately, long before all the water reaches 60°C. Another important characteristic of an electrode boiler is that at a heating-fluid temperature of approximately 20°C, its current and power are usually about 2.5 times lower than at 65–70°C. As the water warms up, its conductivity, the boiler current and the boiler power increase. The small amount of water inside the boiler itself heats up very quickly, but this does not mean that the entire heating system will reach the target temperature within a few seconds. Without proper circulation, only the water inside the boiler body will heat up, which is not a correct operating condition. In practice, it is more useful to assess how quickly the system begins warming the rooms and whether the boiler can compensate for the building’s heat loss.
What is the maximum water temperature the boiler can reach? An electrode boiler does not have its own fixed maximum water temperature. It continues heating the fluid until the power is switched off by a thermostat, controller or safety device. In a normal heating system, the recommended operating temperature is approximately 60–70°C. This is sufficient for most radiator systems and helps prevent excessive increases in current, pressure and thermal stress on the installation components. Technically, an electrode boiler can heat water to boiling point if there is no circulation or if the control system fails to switch off the power. However, this is an emergency condition and must not be allowed. Local boiling can produce steam, cause a rapid pressure increase, create unstable current and damage components of the heating system. The maximum permissible temperature depends not only on the boiler, but also on the specifications of the pipes, radiators, circulation pump, expansion vessel, safety valve and control system. For normal operation, the boiler must be used with a functioning temperature controller, circulation pump and safety group. The upper temperature limit should be set according to the system design, usually no higher than 70–75°C.
How do I choose the right boiler power for my house? The power of an electrode boiler should be selected primarily according to the building’s heat loss, not only its floor area. For an initial estimate, you can use approximately 1 kW of boiler power for every 15 m² of heated floor area. For example, a 90 m² house would typically require a boiler of about 6 kW. However, this is only a rough guideline. The actual required power depends on the insulation level, ceiling height, number and size of windows, climate zone, desired indoor temperature, ventilation and the type of building. A well-insulated house may require less power, while an older or poorly insulated building may require considerably more. Approximate GAZDA boiler selection: 20–30 m² — 2–3 kW 40–60 m² — 4–5 kW 60–90 m² — 6–7 kW 80–120 m² — 7–8 kW 120–180 m² — approximately 9–12 kW 180–250 m² — approximately 12–18 kW For larger buildings, the required power should be calculated individually. The available electrical supply must also be considered. Single-phase 230 V GAZDA boilers are available in 2, 4, 6 and 8 kW versions. Higher power normally requires a three-phase 400 V supply. Before choosing a boiler, check the available connection capacity, main circuit-breaker rating and cable cross-section. A small power reserve is acceptable and does not normally cause a proportional increase in electricity consumption. A more powerful boiler compensates for heat loss faster and switches off sooner when the thermostat reaches the set temperature. Monthly consumption is determined mainly by the building’s heat loss, outdoor temperature and selected indoor temperature, not only by the boiler’s nominal power. However, an excessively powerful boiler may require heavier electrical wiring and can cause very rapid heating or frequent switching. The best choice is therefore a boiler powerful enough to compensate for the building’s maximum heat loss, with a small reasonable reserve. For an accurate selection, a building heat-loss calculation is recommended. Alternatively, provide the floor area, ceiling height, insulation level, window type, location and available electrical supply.
How much electricity does the boiler use per month or per year? Electricity consumption depends not only on the boiler’s nominal power, but mainly on how long it is actually switched on. For example, a 9 kW boiler running continuously uses 9 kWh of electricity in one hour. In a heating system, however, the boiler normally does not run continuously. The thermostat switches it on and off as required. When the boiler is switched on, it uses its actual power — for example, about 9 kW. When it is switched off, its consumption is 0 kW. It does not operate continuously at some “average power” of 4.5 kW. The average is created only by alternating periods of operation and shutdown. For example: If a 9 kW boiler runs for 60 minutes in each hour, it uses 9 kWh per hour. If it runs for 30 minutes in each hour, it uses 4.5 kWh per hour. If it runs for 15 minutes in each hour, it uses about 2.25 kWh per hour. With a correctly selected boiler, a very rough estimate for the coldest part of the heating season is an average load of about 50% of the boiler’s nominal power. For a 9 kW boiler, this means an average consumption of about 4.5 kWh per hour, approximately 108 kWh per day or around 3,240 kWh over 30 days. This is only an approximate calculation for a cold period. Actual consumption depends on the building’s heat loss, outdoor temperature, wind, sunlight, insulation quality, selected indoor temperature and heating schedule. During severe frost and cold wind, the boiler may run almost continuously at full power. When the weather becomes milder or the sun warms the building, it switches on less frequently. For example, instead of operating for 30 minutes per hour, it may operate for only 15 minutes. This is why a boiler is selected with a power reserve. If the outdoor temperature and the building’s heat loss were always constant, a smaller boiler could simply run continuously. In practice, the heating demand changes all the time, so the boiler must have enough power for the coldest conditions. The estimate of about 50% of nominal power is suitable only for a rough calculation and only when the boiler has been selected correctly, for example using the guideline of approximately 1 kW per 15 m². Consumption will be much lower in mild weather and may be higher during periods of severe frost. It is important to understand that a more powerful boiler does not automatically mean higher monthly electricity consumption. For example, a 12 kW boiler may heat the system faster and switch off sooner than a 9 kW boiler. With the same building heat loss and the same indoor temperature, the total amount of energy required will be approximately the same. To estimate annual consumption, you can use previous records of gas, coal, firewood, pellets or another fuel. In the Calculators section of our website, there is a calculator that converts previous fuel consumption into approximate electricity consumption while taking the efficiency of different heating systems into account. The efficiency of an electrode boiler in converting electricity into heat is close to 100%. Older or poorly operated solid-fuel systems may have much lower actual efficiency, so comparing only the amount of fuel without accounting for efficiency would be inaccurate.
Can the boiler power be regulated smoothly or step by step? Yes. The power of an electrode boiler can be regulated either in steps or smoothly. The available method depends on the boiler design and the installed control system. In a standard system, most electrode boilers operate in on/off mode. When the thermostat calls for heat, the boiler switches on and operates at its current actual power. Once the set temperature is reached, the thermostat switches the boiler off completely. The actual power of an electrode boiler also depends on the temperature and electrical conductivity of the heating fluid. Current and power are lower when the water is cold and increase as the water heats up. Step control is possible when the boiler or control cabinet allows individual electrodes or separate power groups to be switched independently. In this case, the boiler can operate on one, two or more power stages. For smooth power regulation, special controllers designed for electrode boilers can be used. The single-phase GAZDA GM-106 already has a built-in smooth power regulator. External KROS controllers can be used with other boilers: KROS-110 for single-phase electrode boilers and KROS-325 for three-phase electrode boilers. These controllers can be used with electrode boilers from different manufacturers, provided that the voltage, current and power remain within the limits of the specific controller model. Smooth regulation works by changing the effective voltage supplied to the electrodes. As the voltage changes, the current and boiler power change as well. The user sets the required power level manually. For example, if a boiler can produce 9 kW but the building currently requires only about 5 kW, the controller can be adjusted to approximately that level. The boiler will still switch on and off according to the thermostat, but while switched on it will operate at about 5 kW instead of 9 kW. This allows the boiler to run for longer periods with fewer shutdowns, while reducing the peak load on the cable, circuit breaker, contactor and the building’s electrical supply. A power regulator can also simplify boiler adjustment when the water conductivity is slightly too high. If ordinary water causes a moderately excessive current, the boiler power can be reduced with the controller without immediately diluting the heating fluid with distilled water. However, the controller has a limited regulation range and cannot compensate for a fluid with extremely high conductivity. Automotive antifreeze, for example, may have conductivity 10–15 times above the required level. Using a KROS controller or the built-in GAZDA GM-106 regulator does not make such antifreeze suitable for direct contact with the electrodes. Smooth regulation is not essential in a standard heating system. A correctly sized boiler can operate efficiently with an ordinary water or room thermostat in on/off mode. A smooth regulator is most useful when the maximum power must be limited, the peak electrical load reduced, operating cycles lengthened or boiler current adjustment simplified.
What is the operating principle of an electrode or ionic boiler? An electrode, or ionic, boiler heats the heating fluid directly by passing electric current through the water. Unlike a boiler with conventional heating elements, it does not use a separate metal heater that first heats itself and then transfers heat to the water. Electrodes are installed inside the boiler. An electric field is created between them, causing dissolved ions in the water to move. With alternating current, the direction of this movement changes continuously. The electrical resistance of the water produces heat throughout the volume of fluid between the electrodes. The water therefore performs two functions at the same time: it acts as the heating fluid and as part of the electrical circuit. For this reason, the boiler’s power depends directly on the water conductivity, water temperature, supply voltage and active electrode surface area. Higher water conductivity produces higher current and greater boiler power. If the conductivity is too low, the boiler operates at reduced power. If it is too high, the current may exceed the permitted value and cause the circuit breaker to trip. Water temperature also affects boiler operation. As the water heats up, its conductivity increases, so the current and power normally increase as well. At approximately 20°C, the current may be about 2.5 times lower than at an operating temperature of 65–70°C. An electrode boiler does not create additional energy and cannot have an efficiency above 100%. Almost all of the electrical energy it consumes is converted into heat within the heating system. Its main distinction is that heat is generated directly in the heating fluid, without a separate heating element and without an intermediate heat-transfer stage through a metal sheath. Deposits on the electrodes may reduce current and the boiler’s actual power, but the electricity consumed is still converted into heat. In older heating-element boilers, scale and deterioration of the heating elements can impair heat transfer to the water, increase local overheating and reduce the overall performance of the system. This is why replacing an old heating-element boiler with an electrode boiler may result in faster heating or lower overall electricity consumption in practice. This does not mean that the electrode boiler has an efficiency above 100%; the difference is usually related to the condition of the equipment, heat transfer, circulation and control system. The system temperature is controlled by a thermostat or controller. When the temperature falls below the set value, the boiler switches on. Once the required temperature is reached, power to the electrodes is switched off. The main difference is therefore not the total amount of heat produced, but the method of producing it: the heating fluid is heated directly by electric current without a separate heating element.
How efficient are electrode boilers compared with other electric boilers? New electrode boilers and new heating-element boilers have efficiencies close to 100%. Almost all of the electrical energy they consume is ultimately converted into heat. However, the two types of boiler can age differently in practical operation. In an electrode boiler, heat is generated directly in the heating fluid as electric current passes through it. There is no separate metal heating element and no intermediate heat-transfer surface. This direct conversion of electrical energy inside the heating fluid is the basic operating principle of an electrode boiler. In a heating-element boiler, the internal resistive element heats first, then the metal sheath of the heating element, and only after that is heat transferred to the water. Over time, scale and other deposits may form on the heating elements. These deposits impair heat transfer to the water, causing the heating element and boiler body to operate at higher temperatures while reducing the useful heat transferred to the heating system. Put simply, an old heating-element boiler may continue drawing approximately the same electrical power for which it was designed, while transferring less useful heat to the heating fluid. For example, it may still draw around 9 kW electrically but deliver noticeably less useful thermal power to the heating system. The remaining energy is used in increased heating of the element itself, the boiler body, the surrounding air and other internal thermal losses. This represents a reduction in the operating efficiency of the heating-element boiler. An electrode boiler normally ages differently. If deposits form on the electrodes, electrical resistance increases, current decreases and the boiler’s actual power falls. As a result, the boiler produces less heat, but it also consumes less electricity. For example, if an electrode boiler produces only 6 kW instead of 9 kW because of the condition of the electrodes, it will also consume approximately 6 kW of electrical power and transfer a corresponding amount of heat to the heating fluid. Therefore, an ageing electrode boiler usually loses available power, but the relationship between electricity consumed and heat produced does not deteriorate in the same way. In practical terms, an old heating-element boiler may retain high electricity consumption while transferring less useful heat to the water. With an old electrode boiler, reduced thermal output is normally accompanied by reduced electrical consumption. For this reason, at a comparable useful heat output, an old heating-element boiler may consume more electricity in practice than an old electrode boiler. An electrode boiler does not have an efficiency above 100% and does not create additional energy. Its advantage is the direct heating of the fluid, the absence of conventional heating elements and the fact that a reduction in electrode-boiler power is accompanied by a corresponding reduction in electricity consumption. A heat pump works differently. An electrode boiler converts electricity into heat at approximately a 1:1 ratio, while a heat pump also transfers heat from the air, ground or water. Under suitable conditions, a heat pump can therefore deliver several kilowatts of heat for each kilowatt of electricity consumed
How can I calculate the energy needed to heat a certain amount of water? Our website has a dedicated Calculators section where you can quickly estimate the energy required to heat a specific volume of water from one temperature to another. Simply enter the water volume, the initial temperature and the target temperature. Where applicable, you can also enter the heater power. The calculator will automatically show the required amount of energy and the approximate heating time. The Calculators section also includes other tools related to heating and energy consumption. New calculators are added regularly, so there is no need to perform these calculations manually. Go to the Calculators section of our website and select the appropriate calculator.
Is an electrode boiler cheaper to use than gas, pellets or coal? There is no single answer. Heating cost depends not only on the type of boiler, but also on local energy prices, the building’s heat loss, insulation quality, heating schedule and the efficiency of the entire system. An electrode boiler converts almost all of the electricity it consumes into heat. It does not require a chimney, fuel storage, regular fuel loading, ash removal or burner maintenance. Installation is usually simpler and less expensive than for gas, pellet or coal heating. However, in many countries, electricity costs more per kilowatt-hour of heat than gas, coal or pellets. For this reason, direct electric heating can be more expensive to operate in a poorly insulated building with high heat demand. Gas heating is often cheaper to run when the building is already connected to the gas network and has a modern efficient boiler. However, the total cost should also include the gas connection, project, chimney, annual servicing and fixed charges. Pellets and coal may be cheaper as fuels, but they require storage space, loading, boiler cleaning, ash removal and more maintenance. The actual efficiency of an old or poorly operated solid-fuel boiler may also be much lower than its stated efficiency. An electrode boiler can be particularly cost-effective in well-insulated homes, small buildings, holiday homes, apartments, systems using off-peak or dynamic electricity tariffs, and as an additional or backup heat source. It can also be useful where electricity is produced by a private solar installation. A fair comparison should include more than the fuel price. It should also include the cost of the equipment, installation, servicing, chimney, fuel storage, electricity for pumps and controls, and the real operating efficiency of the existing heating system. The Calculators section of our website includes a tool that converts previous consumption of gas, coal, firewood or pellets into approximate electricity consumption. This provides a more realistic comparison for a specific building.
What are the dimensions of the boiler and how much installation space is required? The dimensions of a GAZDA electrode boiler depend on the series and power rating, but the boiler body itself is compact. Typical dimensions are: Single-phase GAZDA KE boilers, 2–8 kW: approximately 100 × 50 × 320 mm. GAZDA GM-106 with an integrated power controller: approximately 250 mm high, 90 mm wide and 58 mm deep. Three-phase GAZDA R and BE boilers, 3–15 kW: approximately 85 × 150 × 220–330 mm. GAZDA BE boilers, 18–25 kW: approximately 165 × 100 × 390–430 mm. GAZDA BE boilers, 36–50 kW: up to approximately 220 × 140 × 480 mm. The dimensions of the boiler itself should not be confused with the space required for the complete heating installation. Additional space is needed for the circulation pump, filter, shut-off valves, safety group, expansion vessel, electrical control panel, contactor and temperature controller. Most GAZDA boilers are installed vertically on a solid, non-combustible wall. Free space should be left below the boiler, at least equal to the height of the boiler body, so that the electrode can be removed for inspection or maintenance. Sufficient access must also be provided to the pipe connections, electrical wiring and control equipment. Depending on the hydraulic layout, approximately 40 cm of vertical pipework may also be required above the boiler. There is no single standard size for the complete installation because the pump, expansion vessel and electrical panel can be positioned next to the boiler or elsewhere nearby. Before installation, check the dimensions of the selected model and agree on the location of all components with the installer.
Can an electrode boiler be connected together with another heating source, such as a pellet or gas boiler? Yes, an electrode boiler can be connected to the same heating system as another heat source, such as a gas, pellet, solid-fuel boiler, or heat pump. This type of arrangement is commonly used when the electrode boiler serves as a backup, supplementary, or off-peak heating source. Depending on the system design, the electrode boiler can be connected: In parallel — both heat sources operate within the same system independently. In series — the heating fluid passes through both boilers. Through a hydraulic separator or buffer tank — when the circuits need to be separated or the control system is more complex. In practice, a parallel connection is often the simplest solution. It allows the electrode boiler to start automatically when the main boiler is switched off, cannot meet the heating demand, or is under maintenance. A buffer tank is not always required. Its necessity depends on the design of the entire installation, not on the electrode boiler itself. In a simple, correctly balanced system with two heat sources, the boiler may operate without a buffer tank. In more complex systems with several heating circuits, underfloor heating, different operating temperatures, or multiple circulation pumps, a buffer tank or hydraulic separator can simplify hydraulic balancing and control. The system design must correctly coordinate: the direction of heating-fluid circulation; the position of circulation pumps and non-return valves; thermostat and controller operation; protection against unwanted simultaneous boiler operation; system temperature and pressure. There is no universal connection diagram suitable for every installation. The correct solution depends on the type of the main boiler, the number of heating circuits, and the required control logic. GAZDA electrode boilers are suitable for use in combined closed heating systems, including parallel connection to an existing boiler.
How do I choose the right circulation pump for an electrode boiler system? The circulation pump should be selected according to the characteristics of the entire heating system, not only according to the power of the electrode boiler. The boiler itself usually creates relatively little hydraulic resistance. The main resistance comes from the length and diameter of the pipes, the number of radiators or underfloor-heating loops, valves, fittings, heat exchangers, and the overall layout of the building. The main pump parameters are: Flow rate — the volume of heating fluid the pump must circulate through the system per hour. Head — the hydraulic resistance that the pump can overcome. Connection size and installation length — the pump must physically fit the heating installation. The required flow rate can be estimated using the following formula: Flow rate, m³/h = boiler power, kW ÷ (1.16 × temperature difference between flow and return, °C). For example, for a 6 kW boiler with a 10°C temperature difference between the flow and return: 6 ÷ (1.16 × 10) ≈ 0.52 m³/h. This means that the pump should provide at least approximately 0.5 m³/h at the actual hydraulic resistance of the system. Radiator systems are commonly designed for a temperature difference of approximately 10–20°C, while underfloor-heating systems usually operate with a difference of approximately 5–10°C. For many small houses and apartments, the following common pump sizes are used: 25-40-180 — for compact heating systems with relatively low hydraulic resistance; 25-60-180 — for longer systems, multi-storey houses, or installations with a larger number of radiators or heating loops; a larger pump should be selected only after a hydraulic calculation if the system is especially large or complex. In common circulation-pump markings: 25 usually indicates the connection size; 40 or 60 indicates the maximum head, approximately 4 or 6 metres of water column; 180 indicates the pump installation length in millimetres. The number of floors in the building must also be considered. In a house with two or more floors, the circulation pump must provide stable heating-fluid circulation through the entire system, including the most distant radiators on the upper floors. A multi-storey installation usually has longer pipework, more fittings, more radiators, and therefore greater overall hydraulic resistance. In a closed heating system, the pump does not simply “lift” the water to the upper floors in the same way as a water-supply pump. The static pressure in the flow and return pipes largely balances itself. However, the pump must still overcome the hydraulic resistance of the complete circuit and maintain sufficient flow through the second, third, or higher floors. For this reason, a multi-storey house may require a pump with a higher available head, such as a 25-60-180 instead of a 25-40-180. The final choice should still be based on a hydraulic calculation rather than only on the number of floors. A pump that is too weak may cause poor circulation. The most distant or upper-floor radiators may remain cold, the temperature difference between the flow and return may become too large, and the boiler may heat the fluid near itself without transferring heat effectively throughout the building. A pump that is too powerful is not automatically better. It may cause noise in pipes and valves, increase electricity consumption, and disturb the hydraulic balance of the system. A pump with adjustable speed or automatic differential-pressure control is usually the better solution. For underfloor heating, the pump should be selected separately according to the number and length of the loops, the manifold, flow meters, and mixing arrangement. In a combined system with radiators and underfloor heating, two circulation pumps may be required: one for the main boiler circuit and another for the underfloor-heating mixing group. The final pump selection should be based on the required flow rate and the hydraulic resistance of the complete heating system, not only on the boiler’s rated power.
Can an electrode boiler be used with underfloor heating? Yes, an electrode boiler can be used with an underfloor heating system. From the boiler’s point of view, there is no fundamental difference between radiators and underfloor heating: it heats the heating fluid, which then circulates through the heating circuits. The main difference is the operating temperature. Radiator systems often use a higher flow temperature, while underfloor heating usually requires a significantly lower temperature to avoid overheating the floor covering and the room. There are two main installation options: Underfloor heating only. The boiler can be set directly to the required heating-fluid temperature. A combined system with radiators and underfloor heating. In this case, a separate mixing unit is usually required to reduce the flow temperature supplied to the floor-heating circuits. Such a mixing unit may include: an underfloor-heating manifold; a separate circulation pump; a three-way or thermostatic mixing valve; flow meters and regulating valves; temperature sensors and control equipment. The circulation pump must be selected according to the number and length of the heating loops and the total hydraulic resistance of the system. If the loops are long or numerous, the main boiler-circuit pump may not be sufficient. The flow temperature must also be set correctly. Excessive temperature can overheat the floor, damage some types of floor covering, and reduce comfort. The temperature should therefore follow the underfloor-heating design and the recommendations of the pipe and flooring manufacturers. GAZDA electrode boilers are suitable for underfloor heating in closed heating systems. The correct hydraulic arrangement depends on whether the installation uses underfloor heating only or combines it with radiators.
Can an electrode boiler heat domestic hot water directly? No, an electrode boiler should not heat domestic hot water directly. The water that passes through the electrode boiler is the heating fluid of a closed heating system and must not then be supplied to taps, showers, or other domestic water outlets. For domestic hot water production, the electrode boiler should be used indirectly through a heat exchanger. The most common solution is an indirect hot water cylinder with an internal coil. The electrode boiler heats the fluid in the heating circuit, and that fluid transfers heat to the domestic water stored in the cylinder. A plate heat exchanger may also be used if the system is designed correctly. Direct heating is not recommended for several reasons: the heating fluid in an electrode boiler must have a specific electrical conductivity; substances may be added to adjust that conductivity; the fluid circulates in a closed heating circuit and is not intended for drinking or domestic use; direct connection would compromise the safe and stable operation of the system. Therefore, an electrode boiler can provide domestic hot water, but only through a separate hot water cylinder or heat exchanger. The GAZDA documentation also specifies that domestic hot water systems should operate through a heat exchanger.
Do I need a buffer tank with an electrode boiler? A buffer tank is not a mandatory component in a system with an electrode boiler. In a simple closed heating system with one correctly sized boiler, proper circulation, and sufficient heating-fluid volume, the electrode boiler can operate without a buffer tank. A buffer tank should not be confused with an expansion vessel. A diaphragm expansion vessel is required in a closed heating system because it compensates for the increase in fluid volume as the system heats up. A buffer tank serves a different purpose: it stores thermal energy and helps stabilize the hydraulic operation of the system. A buffer tank may be useful when: the electrode boiler operates together with a gas, pellet, solid-fuel boiler, or heat pump; the system has several heating circuits with different pumps and operating temperatures; radiators and underfloor heating are used together; the heating-fluid volume is too low, causing the boiler to switch on and off frequently; hydraulic separation is required between the boiler circuit and the heating circuits; heat needs to be stored during lower-cost electricity tariff periods. In a small, correctly designed system, a buffer tank may be unnecessary. It increases installation cost, requires additional space, increases the total heating-fluid volume, and creates additional heat losses. The larger the system volume, the more energy and time are required for the initial warm-up. Therefore, a buffer tank is installed not because of the operating principle of the electrode boiler itself, but because of the hydraulic design and operating requirements of the entire heating system. In most standard systems with one boiler, it is not required. In complex or combined installations, however, it can simplify control and improve system stability
How should the boiler be maintained and does it need regular service? Maintaining an electrode boiler is generally straightforward and does not require mandatory annual servicing if the system operates normally. The main components to monitor are the heating fluid, filter, electrical connections, circulation pump, and electrodes. The following checks are recommended: Clean the strainer filter at least once per heating season. Check the system pressure and the condition of the expansion vessel. Remove air from the system. Verify correct operation of the circulation pump. Periodically inspect and tighten electrical connections. Compare the actual boiler current with the normal values for the specific model and heating-fluid temperature. The condition of the electrodes should be assessed primarily by the actual performance of the boiler, not only by age. If the current and output remain within the expected range, the boiler heats normally, and circulation is correct, there is no need to dismantle the boiler unnecessarily. When ordinary tap water with an electrical conductivity of approximately 200–300 µS/cm is used, GAZDA boiler electrodes can typically last around 10 years or longer in practical operation. This is an approximate service life, not a fixed replacement interval. Actual durability depends on water quality, operating temperature, current, operating time, and the condition of the heating system. During operation, the electrode surface gradually wears away. The metal is slowly consumed, and the surface may become uneven or appear as though it has been “eaten away.” This is normal operating wear and does not necessarily indicate a fault. Black deposits and scale may also form on the electrode surface. In a new, clean system filled with fresh water, the electrodes usually do not need cleaning during the first two years. The first inspection and cleaning can normally be carried out after approximately three years of operation. After that, if the system continues to work correctly, cleaning once every two years is usually sufficient, or only when a noticeable loss of output occurs. To clean the electrode, remove it and carefully take off the black deposits using: fine sandpaper; a standard file; another suitable mechanical method that does not remove excessive amounts of metal. After cleaning, reinstall the electrode. Over a service life of around ten years, this procedure may only be needed two or three times, and in some systems even less often. The electrode should not be replaced according to a calendar schedule. Replacement is required only when wear becomes significant enough to affect boiler output, operating current, or heating stability. Minor surface irregularities, dark deposits, or gradual reduction in electrode diameter do not by themselves mean that the electrode is no longer usable. The heating fluid also does not need to be replaced every year. If the water remains clean, the system is sealed, the conductivity has not changed significantly, and the current remains within the expected range, the same heating fluid can continue to be used. Professional inspection is recommended if: the boiler starts tripping the circuit breaker or RCD; the current becomes significantly higher or lower than normal; the boiler heats less effectively; leaks appear; the controller becomes unstable; circulation deteriorates; cleaning the electrodes does not restore normal output. Therefore, a GAZDA electrode boiler does not require annual dismantling or complex servicing. In most cases, seasonal checks of the filter, system pressure, pump, and electrical connections are sufficient, while the electrodes only need cleaning once every few years according to their actual condition.
How can I check whether the electrodes are still in good condition? The condition of the electrodes should not be checked by dismantling the boiler immediately. If the boiler has lost power or the heating system has started warming up more slowly, the first step is to check the heating fluid and the condition of the entire system. In many cases, reduced performance is caused not by worn electrodes but by dirty water. Over time, corrosion products, sludge, scale, and other impurities may accumulate in the heating fluid. These contaminants can reduce circulation, clog the filter, change the electrical conductivity of the water, and lower the actual output of the electrode boiler. The system should therefore be checked in the following order: Check and clean the strainer filter. Make sure the circulation pump is operating correctly and that there is no air in the system. Check the boiler current after the heating fluid has reached its normal operating temperature. Inspect the water for heavy discoloration, sediment, rust, or other contamination. If necessary, drain the old water and flush the heating system thoroughly with clean water. A heavily contaminated system should preferably be flushed several times. Refill the system with clean water of suitable electrical conductivity and test the boiler again. After flushing and replacing the heating fluid, allow the boiler to reach its normal operating temperature and measure the current again. If the current and output return to normal, there is no need to dismantle the boiler. The electrodes should only be inspected if the output remains too low after the system has been flushed, the water replaced, and the filter, pump, electrical supply, and water conductivity checked. Electrode inspection is particularly reasonable when the boiler has been operating for six or seven years or longer and has never been opened or cleaned. During a visual inspection, the following conditions are usually acceptable: black deposits; minor scale; an uneven surface caused by gradual wear; moderate reduction in the electrode diameter. Black deposits and hard scale can be removed with coarse-grit sandpaper or a standard file with a coarse, aggressive cut. There is no need to polish the electrode to a perfectly smooth finish, and excessive metal should not be removed. After cleaning, reinstall the electrode, refill the system, and check the current after the heating fluid has fully warmed up. The electrode should only be replaced if it is severely worn—for example, if it has become significantly thinner, is deformed, has deep damage, damaged threads, cracks in the insulator, or if the boiler output does not recover after the electrode has been cleaned and the heating fluid replaced. The main principle is: check the water and the complete heating system first, and only then inspect the boiler and its electrodes. Clean heating fluid, a flushed system, and a clean filter are beneficial in every case and often restore normal boiler performance without dismantling the unit.
What should I do if the boiler heats poorly or heats up slowly? If an electrode boiler heats poorly or raises the temperature too slowly, do not dismantle the boiler or clean the electrodes immediately. First check the heating fluid, circulation, and the actual output of the complete system. The most common causes are: dirty water, sludge, rust, or other contaminants in the system; a clogged strainer filter; air in the pipes or radiators; insufficient heating-fluid circulation; water conductivity that is too low; incorrect thermostat or controller settings; boiler output that is too low for the building’s heat loss; electrode contamination or heavy wear after long-term operation. The system should be checked in the following order. 1. Check the water and the condition of the system Dirty water is one of the most common causes of reduced performance. Corrosion products, sludge, and deposits can restrict circulation and change the electrical conductivity of the heating fluid. If the water is dark, cloudy, or contains sediment: Drain the old heating fluid. Flush the system with clean water. If the system is heavily contaminated, repeat the flushing process several times. Clean the strainer filter. Refill the system with clean water of suitable electrical conductivity. Afterward, allow the boiler to reach its normal operating temperature and check its performance again. 2. Check water conductivity and current draw The output of an electrode boiler depends directly on the electrical conductivity of the heating fluid. If conductivity is too low, the boiler current and output will also be too low. If conductivity is too high, the boiler may draw excessive current and trip the circuit breaker. GAZDA boilers are generally designed to work with tap water having an electrical conductivity of approximately 200–300 µS/cm at 20°C. The current should be checked not only immediately after start-up but also after the system has warmed up. With cold water, an electrode boiler draws significantly less current. At a heating-fluid temperature of around 15°C, the current may be approximately 2.5 times lower than at normal hot operating temperature. Therefore, low current immediately after a cold start does not necessarily indicate a fault. 3. Check circulation Make sure that: the circulation pump is running; the selected pump speed is sufficient; the filter is not clogged; there is no air trapped in the system; all required valves are open; the heating fluid can circulate freely through the radiators or underfloor-heating loops. If circulation is poor, the fluid near the boiler may heat up quickly while the heat is not distributed effectively through the system. Distant radiators or upper floors may then remain cold. 4. Check the control settings Check: the switch-on and switch-off temperatures; the position and operation of the temperature sensor; the room thermostat settings; the contactor and controller operation; whether the temperature difference between switch-on and switch-off is set too narrowly. In some cases, the boiler itself is working correctly, but the control system switches it off too early or does not allow it to operate long enough. 5. Compare boiler output with the building’s heat loss The boiler may be operating normally but still fail to raise the temperature if the building is losing heat at the same rate as the boiler is producing it. This often happens when: the boiler is undersized; the building is poorly insulated; the outside temperature is very low; the roof, walls, or windows have high heat losses; a completely cold building is being heated from a low starting temperature. In such conditions, the water temperature may remain almost unchanged for a long time because the building immediately absorbs all the heat produced. 6. Inspect the electrodes only after the other checks If the system has been flushed, the water is clean, conductivity and current have been checked, and the pump and controls are working correctly, but the boiler output is still too low, then the electrodes can be inspected. This is particularly relevant if the boiler has been operating for six or seven years or longer and has never been dismantled or cleaned. Possible electrode conditions include: black deposits; hard scale; mineral buildup; normal signs of gradual wear. Deposits can be removed with coarse-grit sandpaper or a file with a coarse, aggressive cut. There is no need to polish the electrode to a perfectly smooth finish or remove unnecessary metal. After cleaning, reinstall the electrode, refill the system, and check the current again after the heating fluid has fully warmed up. The correct diagnostic order is: water, filter, pump, air, conductivity, and controls first — boiler dismantling and electrode inspection only afterward.
How do I start and adjust the boiler after the first installation? After the first installation, an electrode boiler should be started step by step. The purpose of the initial start-up is to check the system for leaks, verify circulation, confirm the electrical conductivity of the heating fluid, monitor the current draw, and test the control equipment. The boiler should not be adjusted to maximum output immediately without first checking the system. 1. Flush the heating system Even a new system should be flushed with clean water before commissioning. This helps remove installation debris, metal particles, sealing residues, and other contaminants. If the heating system is old, flushing is especially important. A heavily contaminated system should preferably be flushed several times, and the strainer filter should then be cleaned. 2. Fill the system with clean heating fluid For most GAZDA boilers, ordinary tap water with an electrical conductivity of approximately 200–300 µS/cm at 20°C is suitable. After filling the system: check all connections for leaks; remove air from radiators, pipes, and manifolds; set the correct system pressure; make sure the expansion vessel and safety group are connected correctly. If there is no heating fluid inside the boiler, it will simply not produce heat. The electrodes remain in air, so practically no operating current flows through the boiler. There is no conventional heating element that can burn out. Air pockets also do not cause the electrode boiler itself to burn out, but they may restrict circulation and prevent the heating system from warming evenly. 3. Check circulation Start the circulation pump before checking full heating operation and confirm that the heating fluid can move freely through the entire system. Check that: the circulation pump is running; all required valves are open; the strainer filter is not clogged; the radiators or underfloor-heating loops are filling and warming evenly; there is no trapped air or abnormal circulation noise. If circulation is weak or absent, the system will not distribute heat correctly, even if the boiler itself is operating. 4. Check the electrical installation Before the first start-up, a qualified electrician should verify: correct phase and neutral connections; correct installation of protective devices; power-cable cross-section; circuit-breaker rating; contactor and thermostat wiring; tightening of all terminals; compliance with the wiring diagram for the specific boiler series. The electrical installation should be completed and checked by a qualified specialist. 5. Set a moderate initial temperature For the first start-up, set a moderate heating-fluid temperature, for example approximately 35–45°C, and observe how the system behaves. Check the settings for: the lower temperature threshold at which heating starts; the upper temperature threshold at which heating stops; the room thermostat, if connected; the boiler start delay after the circulation pump switches on, if supported by the controller. Once stable operation has been confirmed, the temperature can be increased gradually to the required operating level. 6. Monitor the current during warm-up This is one of the most important stages of commissioning. The current draw of an electrode boiler depends on both the temperature and the electrical conductivity of the heating fluid. With cold water, the current is significantly lower than after the system has warmed up. At a heating-fluid temperature of approximately 15°C, the current of a GAZDA boiler may be around 2.5 times lower than at normal hot operating temperature. Therefore, the final boiler output should not be assessed immediately after a cold start. During warm-up: Monitor the heating-fluid temperature. Check the current using an ammeter or clamp meter. Compare the measured current with the reference values for the specific boiler model. Confirm that the current increases gradually and does not exceed the permitted level. 7. Adjust the output only if necessary If the current remains too low after the system has fully warmed up, the boiler may not reach its required output. Before changing the heating fluid, check: water cleanliness; circulation; trapped air; supply voltage; correct electrical connection; heating-fluid conductivity. If the current is too high, the boiler may overload the circuit breaker. In this case, the water and its conductivity should also be checked. Heating-fluid properties should only be adjusted gradually and on the basis of actual measurements. Salt or other substances should not be added without a confirmed need. 8. Check the operation of the complete system After the system has warmed up, confirm that: the boiler switches on and off at the set temperatures; the circulation pump operates according to the controller settings; radiators or underfloor-heating circuits warm evenly; system pressure remains stable; there are no leaks; the circuit breaker and RCD do not trip; the current corresponds to the expected operating values. During the first few hours of operation, it may be necessary to vent the system again and recheck the strainer filter because remaining installation debris may collect there. 9. Do not dismantle the boiler without a clear reason If the boiler heats slowly after commissioning, first check the water, filter, pump, trapped air, conductivity, electrical supply, and control settings. The boiler should only be dismantled and the electrodes inspected after these causes have been excluded. The correct commissioning sequence is: flush the system, fill it, remove air, verify circulation, check the electrical installation, warm the system gradually, monitor the current, and then adjust the controls.
What does error E2 on the controller mean and how can it be fixed? Error E2 usually refers to a Konlen controller and means that the controller is not receiving a valid signal from the temperature sensor. The most common causes are a broken wire, a loose terminal connection, a disconnected sensor, or a faulty temperature probe. Check the system in the following order: Switch off the controller power. Do not inspect the terminals or sensor wiring while the controller is energized. Check the sensor connection. Make sure both sensor wires are securely connected to the correct controller terminals. Inspect the cable along its full length. Look for sharp bends, cuts, damaged insulation, broken conductors, or signs of overheating. Check the temperature sensor itself. If the cable and connections are intact, the sensor probe may be faulty. In that case, replace it with a compatible sensor. Restart the controller. After restoring the connection, switch the power on again. If the sensor is working correctly, the E2 error should disappear and the display should show the current temperature. In some cases, the error is caused only by a loose contact after installation or maintenance. For this reason, first reconnect and tighten the sensor wires before replacing the entire controller. If error E2 remains after checking the cable, terminals, and sensor, the sensor input inside the controller may be damaged. The controller may then require repair or replacement. Error codes can differ between controller models, so the exact controller model should always be confirmed before repair. On Konlen controllers, E2 usually indicates a broken, disconnected, or missing temperature-sensor signal.
Why does the boiler use a lot of electricity but the radiators do not heat properly? If an electrode boiler uses a lot of electricity, the radiators are hot, but the house is still cold, this usually means that the heat is being absorbed by the building itself or lost too quickly. This commonly happens after the heating has been switched off for a long time and the entire building has become cold, including: walls; floors; ceilings; furniture; the full thermal mass of the building. After the heating system is started, the boiler must warm not only the air but also the structure of the house. During this period, the radiators may be hot, the boiler may run almost continuously, and the indoor temperature may still rise slowly. In cold weather, warming a completely cooled building can take two or three days. During this initial warm-up period, electricity consumption may be two or even three times higher than the normal expected level. Once the walls, floors, and other structures have warmed up, the boiler begins to cycle normally and electricity use usually falls. The most common causes of high consumption while the house remains cold are: the building has been without heating for a long time; the walls and floors are still cold; poor insulation; very low outdoor temperature; high heat loss through the roof, walls, windows, or ventilation; insufficient boiler output for the building’s heat loss; insufficient radiator output. If the radiators are actually cold because of poor circulation, closed valves, or trapped air, the boiler will usually heat the water near itself very quickly and switch off according to the temperature sensor. In that situation, electricity consumption will normally be relatively low, not high. Therefore, high electricity use with a cold house usually does not mean that the heat is failing to reach the radiators. It more often means that the building has not yet warmed through or that its heat losses are too high. After the temperature stabilizes, check: whether the average daily electricity consumption decreases; whether the set indoor temperature can be maintained; whether the boiler output matches the building’s heat loss; whether the radiators provide enough heat; whether there are excessive losses through the walls, roof, windows, or ventilation.
Where can I buy spare parts, controllers and accessories for the boiler? Spare parts, controllers, and accessories for GAZDA boilers are listed in our www.galanshop.eu online store. We primarily keep the range of boilers and control units up to date, while separate components such as temperature controllers, electrodes, sensors, and other heating-system accessories are added gradually. The product range changes continuously. If an item is available, it is listed on the website and can be ordered. If a particular controller, electrode, or other spare part is not shown on the website, it means that it is currently unavailable or has not yet been added to the range. For this reason, the website always provides the most accurate information about current availability. The catalogue is updated as new products and spare parts become available.
Who should I contact if I have problems with purchase, delivery, installation or operation? If you have questions about purchasing, payment, delivery, installation, or the operation of a GAZDA boiler, please contact me via WhatsApp. The number is listed in the footer of the website. My name is Yan. I am based in Łódź, Poland, and I personally manage the GalanShop online store, sales, and customer support. You can write to me in your own words and in any language that is convenient for you. There is no need to translate your message into English or Polish. I usually reply quickly as soon as I see the message, including in the evenings and at weekends.