Frequently Asked Questions

In boilers, 90% of the cost is raw materials (metals) and only 10% is labour. Metals cost the same worldwide for equivalent quality. Stoves and heat pumps, by contrast, are lightweight assemblies built from many small components — low material cost, high labour content. That is why cheap options exist there but not in boilers.

With a branded boiler you are not just buying a machine — you are buying technology and engineering know-how. Specifically:

• Performance monitoring, which means fuel savings
• Emissions control for reduced environmental impact
• Automation and ease of use
• Reliable service and spare parts availability over the long term

• Room thermostat control — operates exactly like an oil boiler
• Automatic coordination with the oil boiler — no manual valve intervention required
• Magnetic damper — full airflow control and fail-safe protection
• Flue gas sensor — optimal combustion and fuel efficiency
• Ember retention system — the boiler shuts down completely only 2–3 times per winter
• 3 registered patents in combustion control technology

According to European standard EN303-5: 5mm in the combustion chamber (where the flame directly impinges), 4mm where only flue gas contacts the surface, and 3mm where only water is in contact. Thicker external casing adds nothing — it only increases cost.

Welded steel. Cast iron cannot withstand thermal shock — and inside the combustion chamber you simultaneously have a flame at 700°C, embers at 1200°C, and cold wood that has just been loaded. Cast iron boilers are also 2.5 times heavier for equivalent structural strength.

For domestic boilers, wire welding (MIG/MAG) is entirely adequate. Electrode welding is reserved for refineries and steam boilers operating at 300+ bar. For residential boilers, exceeding the required specifications only drives up costs unnecessarily.

EN303-5 requires seamless pipes because they withstand alternating thermal loads and corrosive environments. Axinar uses exclusively Mannesmann seamless pipes — they cost 1.8× more than welded alternatives, but guarantee long-term reliability and service life.

Genuine fire-resistant steel withstands up to 900°C and costs roughly €10/kg — using it for a full boiler shell would cost around €2,000. In reality, the boiler's steel plate never exceeds 130°C because it is continuously cooled by water. Fire-resistant plate is completely unnecessary here — this is a marketing claim worth scrutinising.

EN303-5 specifies approximately 20 suitable steel grades for boiler construction, such as E235 or S235JR. Steel quality cannot be assessed visually — it requires laboratory analysis. Axinar accepts materials only when accompanied by certified quality documentation.

The door is deliberately oversized to accommodate large logs and root wood. As a reference, a 25-litre jerrycan fits through the door opening. Because the door is positioned high on the chamber, the flame does not impinge on it and no heat energy is lost.

It is the grate on which the logs rest, cooled by the boiler's circulating water. In the Axinar boiler the entire interior is water-cooled — this significantly increases efficiency by transferring more heat to the water instead of losing it through the structure.

No. A larger water volume reduces efficiency because the water moves more slowly. Only the inner steel surface (facing the fire) actually heats the water. The Axinar magnetic damper eliminates the risk of overheating, allowing a smaller water volume and better thermal performance.

Closed. An open vessel exposes the water to the atmosphere, continuously introducing air and dust that corrode the system. In a closed circuit, corrosion essentially stops once the initial dissolved oxygen is consumed. A closed system has a significantly longer service life.

No — and it can actually be dangerous if not installed correctly. If the pipe to the open vessel freezes, it becomes worse than a closed system. In a closed circuit at 3 bar, the boiling point rises to 130°C instead of 100°C, providing a much greater safety margin.

It keeps the return water temperature above 55°C before it re-enters the boiler. This prevents tar build-up inside the combustion chamber.

No. The Axinar boiler has a built-in recirculation bypass with a minimum ½-inch bore — no moving parts, nothing to seize, nothing to clog, nothing to maintain. This saves approximately €100 in installation cost compared to a conventional three-way valve setup.

Under the standard, only when the boiler cannot modulate down to 30% of its maximum output — which typically applies to gasification boilers, not conventional wood boilers. A buffer tank can deliver 2–20% energy savings, but a complete installation costs €1,800–€2,500. Whether it makes sense depends on the payback calculation.

No. A buffer tank stores energy — it does not create it. Think of it as a small pot placed under a dripping tap: it collects the drops and releases them all at once, but the tap still drips at the same rate. Managing energy delivery and doubling heat output are two entirely different things.

Using an innovative approach: while the buffer is cold, water heats the building directly. During thermostat-off intervals, the boiler charges the buffer. Once the buffer reaches temperature, it enters the heating loop in series. This eliminates the delay between the initial fire-up and the moment the buffer is ready to contribute heat.

In standard market practice, yes — it is mandatory by regulation for any installation where combustion cannot be stopped by cutting the power. Without it, if the pressure relief valve opens, fresh mains water enters the system carrying dissolved salts and oxygen that corrode the boiler.

Minimum: 2 pressure relief valves (set at 2.5 or 3 bar) and 1 temperature safety valve with a remote sensor for the cooling heat exchanger. Do not save on €30–€100 of safety equipment — the resulting damage can be orders of magnitude more costly.

Immediately after the boiler, with no valves or isolators between them and the boiler. Their discharge pipes must run to a low, visible point — the water discharges at 95–130°C, and the discharge must be observable so that any valve operation can be detected promptly.

Four layers of protection: magnetic damper, recirculation solenoid valve, cooling heat exchanger, and pressure relief valves. The first two are active (electronic); the last two are passive (mechanical).

When the water temperature reaches the set point, the damper seals the air inlet and restricts the fire. Its operation is fail-safe: if any electrical fault occurs, the damper defaults to the closed position.

If the water temperature exceeds the safety threshold, the solenoid valve opens and the water circulates internally. This prevents the building from overheating and preserves the stored energy in the boiler rather than dumping it.

If the temperature exceeds 95–97°C, the safety valve opens and cold mains water flows through the exchanger to cool the boiler. The cooling water never mixes with the heating circuit water — the closed system remains uncontaminated.

The magnetic damper closes automatically (fail-safe), cutting off the air supply and restricting the fire without any risk. The passive safety devices — cooling heat exchanger and pressure relief valves — continue to function without electrical power.

No — quite the opposite. The fan delivers precisely the right quantity of air for efficient combustion. Without it, airflow depends entirely on chimney draught, which varies constantly. Combined with a flue gas sensor, the fan enables optimal combustion and lower fuel consumption.

Multiple factors: chimney cleanliness, flue gas temperature, external weather conditions (ambient temperature and wind), the quantity of wood loaded, and the amount of ash in the firebox. Continuous control is essential precisely because all these variables change constantly.

The upward pull created by the temperature differential between the hot flue gases and the ambient air. It varies significantly with weather, wind, and temperature. When draught is adequate, the Axinar fan remains off and the chimney does the work on its own.

The magnetic damper provides complete control of the air inlet to the boiler. It seals the inlet whenever combustion needs to be restricted or in the event of a power cut. It has no friction surfaces or moving parts that could seize due to heat or combustion residues.

It directly measures excess oxygen in the flue gas. In newer Axinar models it was removed: it is an automotive component costing €300+, and for a 5–8% potential fuel saving the risk and replacement cost was found to outweigh the benefit. It has been replaced by a dedicated flue gas temperature sensor.

A technique in which a portion of the flue gases is returned to the combustion chamber to reduce emissions. It has no practical application in biomass combustion — do not be swayed by marketing claims to the contrary.

By the cubic metre. Volume does not change regardless of how dry the wood becomes. Weight does — 10 tonnes of freshly cut wood can shrink to 6 tonnes once dried. Volume is also easy to verify with a tape measure; weight requires a scale.

12 to 24 months, depending on the wood species and storage conditions.

Not necessarily. Wood dries like laundry — it needs airflow, warmth, and low humidity. Stored under a staircase in a damp basement it will not dry, regardless of time. A practical rule: do not store wood anywhere you would not hang laundry to dry.

In a shaded, well-ventilated area protected from rain, but not in an enclosed damp space. Firewood needs air circulation to dry — the same rule applies: do not store it anywhere you would not hang laundry to dry.

Below 20% is acceptable; below 16% is ideal. At around 50% moisture content, virtually all the energy in the wood is consumed just evaporating the water it contains, leaving nothing for heating.

Absolutely not. Mixing gives the impression of a longer-lasting fire, creating a false sense of economy. In reality, additional dry wood is being burned simply to evaporate the moisture in the wet wood.

With a wood moisture meter — an inexpensive tool widely available in hardware stores. Two metal pins are inserted into the wood and the meter gives an immediate moisture reading.

This is a myth. One litre of water stores 8.4 times more heat than one kilogram of metal. Because the water content represents between one fifth and one third of the boiler's total weight, over 80% of the stored thermal energy resides in the water — not in the metal or the bricks.

A gasification boiler can be up to 20% more efficient — but only when firewood moisture content is below 16%. With higher moisture it may not ignite at all, or it may burn even more wood than a conventional boiler.

Tar condenses on any surface in contact with the flue gas that falls below 63°C. If the boiler water temperature drops below 55°C, tar deposits will form inside the combustion chamber.

Keep the boiler water temperature above 55°C at all times. In the Axinar boiler this is achieved automatically by the built-in recirculation valve and the DHW function — no additional components are needed.

The Domestic Hot Water function. On the Axinar boiler, activating DHW mode keeps the water temperature elevated, simultaneously preventing tar formation in the combustion chamber.

No. 30,000 kcal is 30,000 kcal regardless of whether it comes from wood or oil. A certified 60kW wood boiler delivers exactly the same heat output as a 60kW oil boiler.

According to EN303-5: a 2-hour test at maximum output and a further test at 30% output, both recorded by a calibrated data logger. This standardised methodology applies equally to all European manufacturers.

The split combustion chamber design maximises the heat exchange surface area. The water-cooled grate and fully water-cooled interior ensure that the maximum possible proportion of combustion energy is transferred to the water rather than lost through the structure.

Heat either heats the water or leaves with the flue gas — it does not disappear. The main causes of excessive wood consumption are: incorrect air quantity, poor airflow distribution, tar deposits in the combustion chamber, wet firewood, and incomplete combustion residues.

When air supply exceeds what combustion requires, the surplus air absorbs useful heat and carries it out of the flue — directly increasing fuel consumption for the same heat output.

Even with the correct total air volume, if that air is not well distributed through the fuel bed, incomplete combustion occurs — producing unburnt gases and carbon monoxide. A significant portion of the fuel's energy is wasted.

Tar acts as thermal insulation. Once it coats the combustion chamber walls, heat transfer to the water is severely reduced — the temperature difference across the affected surface can reach 20°C, meaning much more wood is needed for the same heat output.

Dramatically. If you buy 1 tonne of wood at 40% moisture content, you are actually buying 600 kg of wood and 400 kg of water. Approximately 100 kg of dry wood will be burned solely to evaporate that water — effectively doubling your consumption compared to properly dried wood.

Perfect combustion leaves only a small amount of fine powdery ash with no unburnt char. If you find charcoal pieces in the ash, combustion is incomplete and fuel is being wasted.

Absolutely. With modern electronic control, the Axinar wood boiler offers the same comfort and zoning capability as an oil boiler.

You set the desired temperature and the boiler's electronic controller maintains it automatically — ramping up the fire when needed and keeping it in a standby ember state when the building is already warm.

Up to 4 room thermostats via a zone control panel.

Automatically. When you load and light wood, the oil boiler shuts down without any manual valve operation. When the wood burns out, the oil boiler restarts on its own — completely seamless changeover with no user intervention.

The boiler's built-in electronics control one pump and one solenoid valve as standard. This is expandable to 4 zones with the zone panel. No additional hydrostat or separate control panel is required — everything is pre-wired and factory-configured.

The user sets how long the boiler maintains a live ember bed between loads (scale 1–20). Used correctly, the boiler shuts down completely only 2–3 times per winter, eliminating cold re-starts every morning.

The wood boiler is manually fed by nature. In practice, a notification offers limited value because the time between loads depends on many variables. Smart notification features marketed by some brands are primarily a sales tool rather than a meaningful practical benefit.

Yes. If any room thermostat or the water sensor registers a temperature below 5°C, the oil boiler is activated automatically to protect the heating system.

On the contrary — it is straightforward. The user loads the wood, lights it, and closes the door. The boiler's electronic controller handles everything else automatically from that point on.

Panel radiators. They are more efficient: less water volume means lower thermal inertia and faster response, higher water velocity means better heat transfer, and a greater surface area per unit volume improves output for the same flow rate.

The minimum requirements are: 2 pressure relief valves, 1 temperature safety valve on the cooling heat exchanger, and a voltage stabiliser. These are also the only conditions required to maintain the Axinar warranty.

In a dual-boiler installation with an oil boiler: 4 pipe connections and 3 electrical cable connections. All boilers share the same standard connection points — the ancillary components downstream of the boiler are identical across installations.

The self-diagnostic system detects problems early. For non-critical faults, a fallback operating mode is available. Even in the event of complete board failure — such as a lightning strike — the circulator pump can be bridged to keep running until a replacement board arrives.

The ash drawer has a capacity of 34+ litres — sufficient for once-a-week emptying under typical use.

Very easy. The internal baffles and combustion chamber geometry of the Axinar boiler are specifically designed for quick, straightforward cleaning access.

Yes. The controller monitors 14+ operating parameters and displays warning messages before minor issues escalate into failures.

Yes. The boiler includes a data logger that records operating history and fault events, facilitating accurate diagnostics and more efficient servicing.

When all the fuel burns fully, with no unburnt gases and minimal pollutants, transferring the maximum possible heat energy to the boiler water.

Check the ash. Perfect combustion leaves only a small amount of fine, powder-like ash with absolutely no charcoal pieces. If charcoal is visible in the ash, combustion is incomplete and fuel efficiency is being lost.

The EN303-5 standard consolidates the collective experience of European boiler manufacturers since 1974. It defines materials, dimensions, welding types, and minimum safety and emissions requirements. CE certification is not optional — it is the baseline guarantee of a reliable product.

By law: 2 years on mechanical components, 1 year on electronics. Axinar covers 100% of warranty costs — shipping, labour, and parts.

Only the minimum installation requirements: 2 pressure relief valves, 1 temperature safety valve on the cooling heat exchanger, and a voltage stabiliser.

Under EN303-5, the design service life is 25 years, provided the installation complies with the standard's requirements.

Under no circumstances. Axinar does not condone illegal business practices. Only a proper fiscal receipt proves the date and place of purchase — without it, you have no legal recourse whatsoever.

Every legal claim — defect, compensation, warranty service — begins with the receipt. It is also the owner's responsibility to use a licensed plumber and electrician for installation; without this, courts will not recognise any rights arising from faults.