During a power cut, the circulation pump stops and a solid-fuel boiler can overheat. An AVANSA backup power supply switches to battery automatically, keeps the pump running and lets the boiler cool down safely.
updateUpdated: verifiedTechnically reviewed by the ATRIA SK s.r.o. technicians
A solid-fuel boiler (wood, coal, briquettes) has one fundamental characteristic: the fire in the firebox cannot be switched off at the press of a button. When the power goes off, the fuel in the boiler keeps burning, but the circulation pump stops. Water stops flowing from the boiler to the radiators, and the heat the fire is still producing has nowhere to go.
AVANSA backup power supplies belong to the group of professional automatic uninterruptible power supplies (UPS) designed and manufactured to provide continuous power to solid-fuel boilers when the mains supply fails. When the mains fails – or when its parameters fall outside the normal range – the unit switches to battery automatically, keeps the circulation pump running and lets the boiler cool down safely. The switch-over is shown on the unit's display and announced by an audible signal.
When running on battery, the unit delivers a pure sine wave – the same voltage waveform you get from a wall socket on the mains. The pump and boiler electronics therefore receive voltage of the same shape as under normal conditions.
While the mains is healthy, the unit charges the battery (the initial charging current is about 10 A, so it charges faster than a standard charger) and, once charged, keeps it on standby, ready for the next power cut. At the same time, the automatic voltage regulator (AVR) keeps the voltage supplied to connected devices stable.
Standalone AVANSA backup power supplies – the battery is not included. Add a 12 V lead-acid battery (for the 1050 W model, two 12 V batteries connected in series for 24 V) with a capacity matching the backup time you need.
The unit and the battery in a single package. There is no need to hunt for a suitable battery – simply connect it to the unit according to the instructions and connect the unit to the boiler.
All four units share the same design and dimensions – they differ in output, battery voltage and the maximum battery capacity they can charge.
| Model | Max. capacity | Rated output | Battery voltage | Max. battery capacity | Recommended total load |
|---|---|---|---|---|---|
| AVANSA 300 W | 500 VA | 300 W | 12 V | 90 Ah | approx. 150 W * |
| AVANSA 500 W | 800 VA | 500 W | 12 V | 120 Ah | approx. 250 W |
| AVANSA 700 W | 1000 VA | 700 W | 12 V | 150 Ah | approx. 350 W |
| AVANSA 1050 W | 1500 VA | 1050 W | 24 V (2 × 12 V in series) | each of the 2 batteries max. 120 Ah | approx. 500 W |
Common specifications: input voltage 150 – 270 V AC (45 – 65 Hz), output voltage 207 – 241 V AC (50 – 60 Hz), overload protection 110% / 130% (30 s), standby consumption 22 W, dimensions 18.5 × 14.5 × 34 cm (H × W × D). The manufacturer states a switch-over time of < 4 ms for the 500 W, 700 W and 1050 W models. * For the 300 W model, the manufacturer does not state a recommended total load – the 150 W value is derived from the recommendation to load the unit with pumps and motors to no more than 50% of its rated output.
Complete manufacturer data for all four models. The construction and dimensions are the same; the output, voltage and battery capacity differ.
| Parameter | AVANSA 300 W | AVANSA 500 W | AVANSA 700 W | AVANSA 1050 W |
|---|---|---|---|---|
| Maximum capacity | 500 VA | 800 VA | 1000 VA | 1500 VA |
| Rated output | 300 W | 500 W | 700 W | 1050 W |
| Recommended total load | – | approx. 250 W | approx. 350 W | approx. 500 W |
| Battery voltage | 12 V DC | 12 V DC | 12 V DC | 24 V (2 × 12 V in series) |
| Max. battery capacity | 90 Ah | 120 Ah | 150 Ah | 120 Ah (each of the 2 batteries) |
| Transfer time | – | < 4 ms | < 4 ms | < 4 ms |
| Input voltage / frequency | 150 – 270 V AC, 45 – 65 Hz | 150 – 270 V AC, 45 – 65 Hz | 150 – 270 V AC, 45 – 65 Hz | 150 – 270 V AC, 45 – 65 Hz |
| Output voltage / frequency | 207 – 241 V AC, 50 – 60 Hz | 207 – 241 V AC, 50 – 60 Hz | 207 – 241 V AC, 50 – 60 Hz | 207 – 241 V AC, 50 – 60 Hz |
| Output waveform | pure sine wave | pure sine wave | pure sine wave | pure sine wave |
| Overload protection | 110 % / 130 % (30 s) | 110 % / 130 % (30 s) | 110 % / 130 % (30 s) | 110 % / 130 % (30 s) |
| Standby consumption | 22 W | 22 W | 22 W | 22 W |
| Dimensions H × W × D | 18.5 × 14.5 × 34 cm | 18.5 × 14.5 × 34 cm | 18.5 × 14.5 × 34 cm | 18.5 × 14.5 × 34 cm |
The following also applies to all models: initial charging current of about 10 A, recommended battery capacity for optimal charging 50 – 150 Ah, disconnection when the battery is discharged to 10.8 V, short-circuit protection, AVR voltage regulator, display and audible signalling. A dash means that the manufacturer does not state the figure for that model.
Four models cover everything from a single pump on a wood boiler to a boiler room with several circuits. Here is a quick overview of which to choose when.
The smallest model (500 VA) with a battery of up to 90 Ah. With pumps loading it to no more than 50 % of its rated output, it handles loads totalling approximately up to 150 W – that is, one ordinary circulation pump, for example the AVANSA 25/4 or 25/6 (max. 72 or 93 W respectively). It is the cheapest way to protect a simple boiler room with a single circuit.
800 VA, battery up to 120 Ah, loads totalling approx. up to 250 W. It handles the boiler circuit pump together with the boiler electronics or a pump controller. It is also supplied as a set with a 46 Ah battery.
1000 VA, battery up to 150 Ah, loads totalling approx. up to 350 W. Suitable for boilers with an exhaust fan, for two smaller pumps, or where you want a longer backup time with a larger battery. The set with a battery has a 55 Ah accumulator.
1500 VA, loads totalling approx. up to 500 W. It is the only one that works with 24 V – it needs two 12 V batteries connected in series, each with a capacity of no more than 120 Ah. Suitable for several pumps, more powerful pumps and boilers with more demanding electronics.
What matters is the total power input of all the loads the unit is to power during a power cut – not just the pump itself. There are three steps.
Pumps and electric motors are inductive loads – when starting, they may briefly need up to twice their rated power input. The manufacturer therefore recommends loading the backup power supply with such devices to no more than 50% of its maximum output. In practice, multiply the total power input by a factor of 1.5 – 2; for pumps and motors, it is safer to allow for double.
The recommendations for the individual models are based on this rule: AVANSA 500 W is suitable for loads totalling up to approx. 250 W, AVANSA 700 W up to approx. 350 W and AVANSA 1050 W up to approx. 500 W.
The length of time the unit can keep the pump running depends on two things: the energy stored in the battery and the power input of the connected loads. A bigger battery means a longer backup time, a higher load a shorter one. You can work out an approximate time yourself:
The unit also has its own consumption – the manufacturer states a standby consumption of 22 W. If you add this to the load for a more cautious estimate, at 100 W you get: 422 Wh ÷ (100 + 22) W ≈ 3.5 hours.
With the AVANSA 1050 W model, two 12 V batteries are connected in series – the voltage is 24 V and you calculate the energy at 24 V using the capacity of one battery (for example, 2 × 120 Ah in series = 120 Ah × 24 V = 2,880 Wh).
The 46 Ah and 55 Ah batteries are included in the AVANSA 500 W and AVANSA 700 W sets. Calculation according to the method above: capacity × 12 V × 0.8 (usable capacity) × 0.8 (efficiency) ÷ load.
| 12 V battery | Load | Approximate calculation | More cautious estimate (+ 22 W unit self-consumption) |
|---|---|---|---|
| 46 Ah (552 Wh, usable ≈ 353 Wh) | 50 W | ≈ 7.1 h | ≈ 4.9 h |
| 46 Ah | 100 W | ≈ 3.5 h | ≈ 2.9 h |
| 46 Ah | 150 W | ≈ 2.4 h | ≈ 2.1 h |
| 55 Ah (660 Wh, usable ≈ 422 Wh) | 50 W | ≈ 8.4 h | ≈ 5.9 h |
| 55 Ah | 100 W | ≈ 4.2 h | ≈ 3.5 h |
| 55 Ah | 150 W | ≈ 2.8 h | ≈ 2.5 h |
Approximate calculation, not a guaranteed value. The actual backup time may vary depending on the condition and age of the battery, temperature and pump start-ups.
For 12 V batteries with a larger capacity, the manufacturer states the following operating times. They are somewhat more cautious than our calculation – so when planning, go by the lower values.
| Load | 65 Ah battery | 120 Ah battery | 150 Ah battery |
|---|---|---|---|
| 100 W | 3.5 h | 6.5 h | 8 h |
| 200 W | 2 h | 3 h | 4 h |
| 300 W | 1.5 h | 2.5 h | 3 h |
Before buying a larger battery, check the maximum capacity supported by your chosen model: AVANSA 300 W 90 Ah, AVANSA 500 W 120 Ah, AVANSA 700 W 150 Ah, AVANSA 1050 W 2 × 120 Ah (in series).
Procedure according to the manufacturer's instructions. We recommend leaving the connection to the electrical circuit of the boiler and pump to an electrician or heating technician.
A dry place free from moisture, out of reach of water and snow, well ventilated and free from dust or coal dust, which could clog the unit's fan. Leave enough space around the unit for cooling. Do not install the unit in a flammable environment or near fuel.
Remove metal objects – rings, watches, chains, bracelets; there is a risk of short circuit when handling the battery. Clean the battery terminals with a brush before connecting. Use a 12 V lead-acid battery (for the AVANSA 1050 W, two 12 V batteries in series = 24 V); gel batteries are not recommended.
Observe the polarity: red cable (+) to the + terminal, black cable (−) to the − terminal. Tighten the connectors with a spanner to ensure a firm contact. When connecting two batteries in series, link the positive of one battery to the negative of the other and connect the remaining free terminals to the unit.
Plug the unit's main power cable into an earthed 230 V / 50 Hz socket. Never operate the unit without a battery connected – it does not work without one.
Connect the circulation pump and any other loads that need to run during a power cut (boiler electronics, pump thermostat) to the back of the unit. Check that their total power input does not exceed the recommendation for your model.
Hold the ON/OFF button for about 4 seconds. The unit automatically checks the battery and mains status. If the battery voltage is below 10.8 V, the battery may be damaged and the unit will not start.
Pull the unit's power cable out of the socket (or switch off the circuit breaker for its circuit). The unit must switch to battery, announce this with an audible signal and on the display, and the pump must keep running. Then reconnect the power and check that the unit has switched back to the mains.
The unit needs a well-ventilated place free from dust and coal dust – nothing must obstruct its cooling or fan. Operation can produce sparks, so never install it in a flammable environment or near fuel.
The unit is designed to charge lead-acid batteries; gel batteries are not recommended. Voltage 12 V (AVANSA 1050 W: 24 V) and capacity no higher than the limit for the given model.
To extend battery life, the manufacturer recommends discharging the battery and fully recharging it at least once every 2 months – even if there has been no power cut in the meantime.
From time to time, ideally before the heating season, simulate a power cut and check that the unit switches to battery and the pump keeps running.
A lead-acid battery loses capacity over time. If the backup time becomes significantly shorter or the unit reports a weak battery, replace it with a new one after a few years.
All cables must be in good condition, with no exposed insulation. Do not touch the battery terminals during operation.
The switch-over to battery is indicated on the display and by an audible signal. The unit signals a flat battery with faster beeping and cuts the output; an overload above 110% with an intermittent signal and shutdown.
Protection against overload, short circuit and deep discharge of the battery (cut-off at 10.8 V), plus an AVR voltage regulator for a stable supply to connected devices.
The backup power supply is a safety device for the duration of a power cut. Do not use it as an inverter for unlimited continuous operation from a battery.
AVANSA backup power supplies are designed for solid-fuel boilers, but they also keep other appliances that need a stable supply running.
The aim here is to keep the circulation pump running until the fire in the boiler has burnt out and the boiler has cooled down. Power the boiler circuit pump from the unit, together with everything the pump cannot do without – the AVANSA 110 C / 110 E controller or the boiler electronics. As a second safeguard that does not depend on electricity, add a cooling loop with an AVANSA STS safety valve, which cools the boiler with cold water if it overheats above 97 °C.
With a gas boiler, a power cut does not cause overheating – the boiler simply switches off and the house cools down. If you want to keep heating during a power cut, the unit must power the whole boiler, including the electronics, fan and built-in pump. You will find the power input on the boiler's rating plate; add a margin to it according to the 50 % rule. The boiler then runs longer than in an emergency cool-down, so plan for a larger battery. A pure sine wave is important for the electronics of modern boilers – they receive voltage of the same shape as from the mains. Some boilers also require the correct phase and neutral order; check this in the boiler manual and leave the wiring to a service engineer.
Installers, heating contractors and resellers who want to offer AVANSA backup power supplies to their customers can buy on wholesale terms via atria-europe.com.
A backup power supply primarily protects the circulation pump. If you are still choosing a pump or looking up its power input, see the AVANSA circulation pumps page with the technical data of all models. With a solid-fuel boiler, the pump is often switched by an AVANSA thermostat – do not forget to power it from the backup power supply. Every boiler room should also have a gas and carbon monoxide detector.
You will find answers to further questions in the AVANSA advice section, an overview of the whole brand on the home page, and all products are available from the ATRIASHOP.EU online store.
AVANSA backup power supplies and battery sets are available from the ATRIASHOP.EU online store; installers and resellers can buy on wholesale terms via atria-europe.com. We are happy to help you choose the right output and battery – technical questions: +421 917 133 664.
Short videos showing the products, installation and settings.
User manuals, technical data sheets and declarations of conformity for the products on this page (PDF).
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call+421 917 133 664 · mailinfo@atria.sk
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