Maintenance and service of Attack Electric boiler: what and when to check?

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Maintenance and service of the electric boiler Attack Electric: what and when to check?

An electric boiler, compared to a gas or solid fuel boiler, is a device that does not require extensive regular maintenance – it has no combustion chamber, chimney, burner, or ash. Despite this, it would be a mistake to think that you do not need to care for it at all. From practical experience, we know that neglecting seemingly trivial checks – the condition of the safety valve, expansion tank, scale on the heating elements, or the condition of the terminal block – is the cause of the most frequent faults and reduced boiler lifespan. The aim of this article is to give you a concrete, practically tested maintenance procedure for the Attack Electric boilers, so you know what, when, and why to do it – regardless of whether you have an Attack Electric Easy 8, one of the models Attack Electric Excellent 8 / 7.5 kW, or the more powerful Attack Electric Excellent 15 kW.

Why is maintenance important even for an electric boiler?

An electric boiler operates on a simple principle: electrical energy is converted into heat via submerged resistive elements (cartridges) or tubular heating elements, which heat the water in the primary circuit. No combustion process, no emissions, no chimney cleaning. This, however, does not mean the boiler functions forever without intervention. There are several reasons why regular maintenance should not be underestimated:

Water scale – in areas with hard water, calcium carbonate deposits on the surface of the heating elements. A layer of water scale just 1 mm thick reduces heat transfer by 10–15%, which directly results in higher electricity consumption.
Corrosion and sludge – in a closed central heating system, magnetic sludge and corrosive products gradually accumulate, reducing flow, clogging the circulation pump, and shortening the lifespan of the heating elements.
Pressure relief valve and expansion tank – their failure can lead to dangerous overpressure or even system rupture.
Electrical connections – vibrations, temperature cycles, and condensation can cause loosening of terminal screws, and in the worst case, a short circuit or fire in the boiler’s electrical panel.
Warranty conditions – the manufacturer Attack conditions the validity of the warranty on regular maintenance performed by an authorized service technician. Without a service certificate, you may lose your warranty rights.

Overview of the structure of the electric boiler Attack Electric

Before we move on to specific tasks, it is good to know what the main components of the boiler are. This will help you better understand where to look and why you are performing a particular task.

The basic components are: boiler body with heating elements (resistive cartridges or screw-in elements), control electronic board (PCB) with thermostats, relays, and fuses, circulation pump (integrated or external depending on the model), expansion tank, safety valve, temperature sensors (NTC, STB protection), pressure switch, and control panel. In models with accessories for the preparation of hot water for domestic use, there is also an attached TWW module set – preparation of TWW in an external tank with its own pumping circuit and sensors.

Annual maintenance schedule: what, when, and who

In practice, we distinguish three levels of inspection: daily monitoring (can be done by any user), seasonal inspection before and after the heating season (can be done by a technically skilled owner or service technician), and annual professional service (requires a qualified person). Below is a clear table:

Task	Frequency	Performed by
Visual pressure check in the system	Weekly (during the season)	User
Check operating temperature and display	Daily (during the season)	User
Bleeding radiators and boiler	1× per year (September)	User / technician
Check and test safety valve	1× per year	Technician
Check pressure in expansion tank	1× per year	Technician
Visual inspection of electrical installation and terminal block	1× per year	Technician (electrician)
Check heating elements (resistance, scale)	1× every 2–3 years or when performance drops	Service technician
Cleaning / flushing the heating circuit	1× every 5 years or according to water quality	Technician
Check pump (noise, flow)	1× per year	Technician
Check and calibration of temperature sensors	1× every 2 years	Service technician
Check TÚV module and tank (if installed)	1× per year	Technician
Firmware update of control board (Excellent)	According to manufacturer's recommendation	Authorized technician

Daily and weekly checks – what to monitor yourself

Pressure in the system

The pressure in a closed heating system should be between 1.0 – 1.5 bar when the water is cold (i.e., at room temperature). During operating temperature (60–75 °C), the pressure naturally rises to 1.5 – 2.0 bar, which is normal. If the pressure gauge on the boiler indicates less than 0.8 bar, the system is likely losing water due to a leak or was improperly filled. A pressure above 2.5 bar when the water is cold indicates a problem with the expansion tank or overfilling. A simple rule from practice: when returning from the garden on Monday morning, quickly check the pressure gauge – it takes 3 seconds and reveals a lot.

Displayed values on the screen

Modern models such as Attack Electric Excellent 24 / 22 kW or Excellent 15 kW have a detailed display where you can see the current output temperature, set temperature, pump status, active power stage, and any error codes. Get into the habit of glancing at the display once a day (during your morning coffee). If something unusual appears – a blinking symbol, a fault icon, or a numeric code – don’t ignore it. Error codes are described in the manual, or in the article Common faults of Attack Electric boilers and how to solve them, where you can find their interpretation and first steps for resolution.

Pre-heating seasonal check (September – October)

The ideal time to perform a pre-season check is the end of September or the beginning of October – the boiler has been off all summer (or only slightly in operation for TÚV), and you want to be sure that winter won’t catch you with a breakdown. From my own experience, most service calls are concentrated in November – when the first frosts come and people discover that the boiler isn’t working. If you schedule your check yourself in September, you’ll avoid the two-week wait for a technician.

System bleeding

Air in the system is the enemy of efficient heating. It manifests as noisy radiators (clicking, gurgling), insufficient heating of the upper sections of the radiator, and uneven heating. Bleeding procedure:

Turn off the boiler or set it to pump mode without heating.
Start with the highest radiators in the house – open the bleed valve (a small square or screw-type valve) with a key.
Release air until water starts to flow – then close the valve.
Check the system pressure – if it drops below 1.0 bar, add water through the filling valve.
Repeat for each radiator and finally for the boiler itself (it has an automatic air vent, but a manual check won’t hurt).

Check of the safety valve

The safety valve is a safety component that opens the outlet at excessive pressure (standard setting is 3 bar for Attack Electric boilers, 6 bar in some configurations). Testing it is simple but important: manually lift the handle of the valve and check whether water flows through it and whether it closes properly after releasing the handle. If the valve leaks (drips even at normal pressure) or doesn’t open at excessive pressure, it needs to be replaced. Replacement is cheap – the valve itself costs just a few euros – but neglecting this check can end in a system rupture.

Note from practice: We have seen cases where the safety valve was blocked by limescale and didn’t work at all. The owner only discovered it when the boiler made a "popping" sound at overpressure and water leaked from an unexpected location.

Check of the expansion tank

The expansion tank is a sealed tank with a membrane, dividing it into an air and water chamber. Its purpose is to absorb changes in water volume during heating. The standard air pressure in the expansion tank is 0.5 – 0.75 times the system pressure at cold water – typically 1.0 bar. The check is done when the system is depressurized (drained): measure the air pressure at the Schrader valve (like on tires). If it is lower than it should be, inflate it with a regular bicycle pump or compressor. If the membrane has burst (this is indicated by water coming out of the Schrader valve instead of air), the entire tank must be replaced.

Annual technical service – what the technician does

Heating element inspection

Heating elements (electric rods) are the heart of the boiler. Under normal use with water hardness up to 20 °fH (French hardness degrees), an inspection every 2–3 years is sufficient. In areas with water hardness above 30 °fH, an annual inspection is recommended. The technician disassembles the heating element (after draining and depressurizing the boiler), visually assesses the scale thickness, and measures the electrical resistance using an ohmmeter. The correct resistance value depends on the element's power – for example, a 3 kW / 230 V element should have a resistance of approximately 17.6 Ω. A deviation of more than ±10 % indicates insulation damage or overheating. Scale cleaning is done using an acidic bath (citric acid solution, approx. 5–10 % concentration) or mechanically in cases of heavy buildup.

Electrical installation and terminal block inspection

This is an area where a strict rule applies: only a qualified electrician according to Ordinance No. 508/2009 Coll. (at least §21 or §22) may inspect or interfere with the electrical installation. During the inspection, the technician:

Tightens the phase and neutral conductor terminals – thermal cycles loosen them, and a loose terminal can overheat and cause a fire.
Measures the leakage current of the heating elements (insulation resistance to ground, the value should be >1 MΩ at 500 V using a megohmmeter).
Checks the condition of the fuses and relays on the control board.
Verifies the correct grounding of the boiler and the bonding connection.
Checks whether the conductors are correctly dimensioned (for a power of 15 kW at 3× 400 V, this is at least 3× 6 mm² Cu for a length up to 15 m, for 24 kW at least 3× 10 mm²).

Pump and flow inspection

The circulation pump ensures water circulation between the boiler and radiators. Its failure leads to boiler overheating and activation of the STB emergency protection. The technician listens to the pump during operation (noise, vibrations), measures the current draw (compares it to the rated value), and verifies the flow. A clogged filter in front of the pump (Y-filter or magnetic filter) is another element the technician cleans during each visit – in a clogged state, it significantly restricts the flow and overloads the pump.

TÚV module inspection and cleaning

If you have a TÚV module set – hot water preparation in an external tank connected to your boiler, the service inspection also includes this circuit. The main points are: inspection of the TÚV circuit pump, inspection of the tank thermostat, verification of the correct temperature setting (minimum 55 °C to eliminate legionella), inspection of the TÚV circuit safety valve (typically set to 6 bar), and possible tank flushing. For more details on the TÚV module, read the separate article TÚV module for an electric boiler: how hot water is prepared in an external tank?

Water quality in the system – the basis for long service life

This is a topic that is usually covered in one section of the manual, but in practice, it forms the basis for most problems. Attack Electric boilers are designed for water with a pH of 6.5 – 8.5 and total hardness ideally 5 – 20 °fH. What does this mean in practice?

Hardness above 25 °fH – we recommend installing a water softener or magnetic conditioner at the system inlet. Without it, limescale will deposit aggressively, heating elements will need to be cleaned every year, and their lifespan will be halved.
Open system or old cast iron radiators – in old systems, oxygen is a constant problem leading to corrosion and the formation of magnetite sludge (black sediment). We recommend adding corrosion inhibitors (e.g., Fernox F1 or a similar product) with every water top-up.
Too soft water (below 5 °fH) – paradoxically, it is also not ideal, as it is corrosive to copper and brass components. In such cases, the pH is adjusted with additives.
Antifreeze mixtures (non-freezing mixtures) – if the system is filled with a propylene glycol-based mixture, it should be considered that it degrades and must be replaced or have inhibitors added every 3–5 years according to the manufacturer's instructions.

Maintenance specifications by model

Attack Electric Easy 8

The model Attack Electric Easy 8 is a compact boiler with an output of 8 kW, designed for smaller buildings or as an auxiliary heat source. Due to its simpler construction and smaller tank, its maintenance is less demanding – there is only one heating element, the pump is integrated, and the electronics are straightforward. With this model, pay particular attention to: regular air venting (the small system volume is more prone to air blockages), pressure checks (recommended value 1.0–1.2 bar when cold), and annual testing of the safety valve. Since the boiler does not have a complex control electronics with power modulation, diagnostics are usually quick in case of problems.

Attack Electric Excellent – ranges 8, 15, 22 and 24 kW

The Excellent models are more sophisticated – they have multi-stage power regulation (e.g., Excellent 15 kW operates in 5, 10 and 15 kW stages), an advanced control board with communication, the possibility of connecting an external thermostat, OpenTherm or an equithermal. With the maintenance of these models, additional tasks are added to the basic ones:

Check the functionality of individual power stages (relays) – performed by a technician measuring current when switching stages.
Verify the calibrated temperature sensor at the output and return – a deviation of more than 3 °C from the actual temperature can cause incorrect switching.
Update the firmware of the control board – Attack occasionally releases updates that improve regulation and fix minor software errors.
Check OpenTherm communication with the controller (if connected).

For more information on the differences between the Excellent and Easy models, see the article Attack Electric Excellent vs. Easy: what they differ in and which one to choose?

What to do if the boiler does not turn on after summer

This is a classic scenario from practice: the first cold day in October comes, you turn the thermostat, and the boiler... nothing. Or an error code appears. Before calling a service, try these steps:

Check the main circuit breaker and fuses in the distribution board – a summer storm may have tripped a fuse or the FI relay.
Check the system pressure – if it is below 0.5 bar, the boiler has an emergency shutdown due to insufficient pressure. Add water and reset.
Reset the boiler – most Attack Electric models have a RESET button or Reset STB (emergency thermostat). STB is triggered by overheating and remains blocked until manually reset.
Check the thermostat/room controller settings – it may be in summer mode or set to too low a temperature.
Read the error code on the display and compare it with the table in the manual or in the article Common faults of Attack Electric electric boilers and how to solve them.

Economic aspect of maintenance: how much it costs and how much it saves

Annual service of an Attack Electric electric boiler performed by an authorized technician usually costs between 60 – 120 € including transportation and labor (without spare parts). It may seem like a lot? Compare it to the cost of:

Replacing a heating element: 30–80 € (part) + 1–2 hours of labor
Replacing a circulation pump: 80–200 € (part) + labor
Replacing a control board: 150–400 € (part) + labor
Flushing and cleaning the system of sludge: 150–300 € labor
Energy loss due to 2 mm of limescale on elements in a 15 kW boiler: about 22 % extra, i.e., with 1,500 hours per season and a price of 0.20 €/kWh, this is more than 990 € in unnecessary annual costs.

Regular maintenance is therefore not only a guarantee of reliability, but also clean mathematics in favor of your wallet. About how to save even more by setting the regulation correctly, you will read in the article Regulation and setting of Attack Electric electric boiler: how to save on electricity?

When to call the service immediately – signs of urgent faults

Some situations do not require postponing to "next week". Immediately turn off the boiler and contact the service if you notice:

Smell of burnt plastic or ozone near the boiler – indicates a fault in the electrical insulation or a burning relay.
Visible sparking or smoke from the boiler's electrical distribution board.
Water continuously dripping from the safety valve during normal operation – either the safety valve is faulty, or the pressure in the system is constantly above the limit (problem with the expansion tank).
Significant pressure drop (below 0.5 bar) despite regular topping up – there is a leak somewhere.
Electrical circuit breakers repeatedly tripping when starting the boiler.
Error code "E5", "STB" or similar together with warm but non-functional radiators – may indicate a blocked pump or clogged filter.

Service book and documentation

Keep all documentation for the boiler in one place: installation protocol, warranty card, electrical installation inspection report, and records of each service. A service book (physical or digital) is proof that you have taken care of the boiler properly – not only to maintain the warranty, but also when selling real estate. Buyers increasingly require proof of the heating system's condition. Properly kept documentation can increase credibility and property value.

Most frequently asked questions (FAQ)

Must boiler maintenance be performed only by a professional, or can I do it myself?

It depends on the type of task. A visual pressure check, radiator bleeding, and safety valve check (manual testing) can be done by any adult user. Anything related to the electrical part of the boiler – terminal block, insulation measurement, part replacement – must be done only by a person with electrical qualifications according to current legislation (Decree No. 508/2009 Coll.). If you do it yourself without qualifications and damage occurs, the insurance company will not pay out.

How do I know if the heating element needs cleaning or replacement?

The most common signs are: the boiler takes a long time to reach the desired temperature, electricity consumption has visibly increased, or the boiler reports an overheating fault (STB) despite normal flow. A technician can confirm this by measuring the resistance of the element with a megohmmeter and visual inspection after disassembly. Regular prevention – water hardness treatment – is much cheaper than repeated element replacements.

What pressure should the system have in summer when the boiler is not heating?

Even in summer, the pressure in a closed system should be in the range of 1.0 – 1.5 bar (at room water temperature). If you have a TÜV module and the boiler heats only the tank in summer, the same value applies. If the pressure drops below 0.8 bar, add water via the filling valve. Leaving the system under long-term negative pressure means it is sucking in air, which accelerates corrosion.

Can maintenance be performed in winter during the heating season?

Most routine checks (pressure check, electrical inspection, parameter setting) can be done yes. Tasks requiring draining the system (element replacement, filter cleaning, pump replacement) are unpleasant in winter, but feasible – they require fast work and a portable electric heater to maintain room temperature during the shutdown. Much better is to plan these tasks for September or May.

Is it worth buying a magnetic filter for an electric boiler?

Definitely yes, especially in older systems with cast iron panel radiators. A magnetic filter captures magnetite sludge (black sediment from corrosion) and prevents it from settling in the boiler's heat exchanger and pump. Installation costs 50–100 € including labor and filter cleaning takes 5 minutes once a year. In neglected systems, we have pulled out actual mud from the filter during service, which would otherwise clog the circulation pump within a year.

How long does an Attack Electric electric boiler last with proper maintenance?

An electric boiler lasts remarkably long with proper care. Control electronics and heating elements are now made from high-quality materials. Attack Electric boilers last 15–20 years without problems if the rules of proper operation are followed (water quality, regular service). A critical component is the heating elements (replacement every 8–12 years with hard water, longer with soft water) and the circulation pump (typical lifespan 10–15 years). The control board, if not damaged by overvoltage, lasts the entire lifetime of the boiler.

Conclusion

The electric boiler Attack Electric is a reliable and easy-to-operate device that does not require annual chimney cleaning or replacement of burner nozzles. However, neglecting even the most basic checks – pressure, safety valve, expansion tank, condition of heating elements and electrical connections – will sooner or later have consequences: higher electricity consumption, a breakdown at the worst possible moment, or a shortened device lifespan. The most sensible approach is a combination of regular self-monitoring (pressure, display) with one professional service inspection per year, ideally before the start of each heating season. If you are looking for a specific model or accessories, you can find the entire range on the Attack Electric website. Choosing the right power can also be helped by the article What electric boiler power do I need for my house?, and for complete hot water preparation, take a look at the options of the TÚV Module Set.

Do you have a question on this topic?

Having trouble deciding or dealing with a specific situation in your home? Write to us – we are happy to help.