Comparison of Avansa backup power sources by power
Why compare Avansa backup power sources by power output
When a customer comes with the question "which backup power source should I buy for my boiler," the first thing to clarify is not the price or design, but the power output and the resulting battery capacity. The Avansa range offers five models in the category of backup power source for boiler and circulation pump, which differ precisely in power - from 300 W up to 1050 W. The difference between them is not just a number on the label, but in which appliances they can safely start, how long they can keep them running, and whether they can handle the surge load during the start-up of the boiler's pump or fan. In practice, I often encounter customers who choose a power source based on price or because "the neighbor had it," and then wonder why the unit shuts off after a few seconds or why the boiler does not start during a power outage. This article is therefore focused exclusively on comparing the power parameters of the entire Avansa range, so you can see which model corresponds to your real load.
Overview of the entire Avansa range and their rated power outputs
The Avansa range in this category consists of five products: Avansa 300 W, Avansa 500 W, Avansa 500 W + battery 46Ah, Avansa 700 W, and Avansa 1050 W. The numbers in the name indicate the rated (continuous) power, i.e., the power that the device can deliver long-term without overloading. The peak power that the device can withstand briefly during the start-up of the pump motor is usually 30 to 100% higher, depending on the specific model and the quality of the internal inverter.
Below is a graphical comparison of the rated power outputs of the individual models, to make the difference between them immediately clear at a glance:
From the graph, it is evident that there is more than a threefold difference in power between the weakest and the most powerful model. This directly affects how many appliances and of what type the power source can serve simultaneously.
Detailed comparison of the parameters of individual models
Avansa 300 W - Entry-level for a small circulation pump
Avansa 300 W is the smallest model in the range and is intended mainly for backing up a single circulation pump or the electronics of a smaller gas boiler without larger accessories (without a fan with higher power consumption, without additional modules). The actual consumption of a standard circulation pump ranges from 30 to 90 W, so a reserve of 300 W is sufficient for one pump, with a certain technical reserve for the starting current. When combining a boiler and a pump simultaneously, this model often reaches its limit, especially if the boiler has a fan with a power consumption of 100 - 150 W and control electronics.
Avansa 500 W - The most universal choice
Avansa 500 W belongs to the most sold models precisely because it covers the most common real scenario - simultaneous operation of a circulation pump and the electronics of a condensing gas boiler, including a fan. A standard condensing boiler consumes 80 to 150 W in operation, and the pump adds another 40 to 90 W, totaling 120 to 240 W continuously. A reserve of 500 W leaves room for short-term peaks during the start of the fan or burner ignition.
Avansa 500 W + battery 46 Ah - Same power, significantly longer runtime
The model Avansa 500 W + battery 46Ah has the same rated power as the basic 500 W version, but is equipped with a significantly larger battery. While standard versions usually operate with a battery in the range of 7 - 9 Ah, this one has a battery capacity of 46 Ah, which means approximately 4 - 6 times longer operational runtime under the same load. This model is suitable especially where the customer expects longer power outages (rural areas, cottages, locations with frequent distribution network faults) and does not want to deal with multiple purchases of external batteries.
Avansa 700 W - Reserve for multiple appliances at once
Avansa 700 W is suitable if you need to back up a boiler, circulation pump, and also, for example, an equithermal regulation, smart thermostat, or a second smaller pump (e.g., in a system with two heating circuits). This reserve is useful where the boiler is of an older type with a higher starting current of the fan, or if the heating system of hot water is backed up in one distribution panel.
Avansa 1050 W - The highest class in the range
Avansa 1050 W is the flagship of this category and is intended for more demanding installations - for example, houses with multiple heating circuits, cascaded boiler connections, or situations where it is necessary to back up a solar system circulation pump or a low-power heat pump with an auxiliary electric heater simultaneously. This model also provides the largest reserve for future system expansion, which is important especially in new buildings where technology is planned to be gradually expanded.
Comparison table of power outputs and approximate usage
| Model | Rated power | Typical battery | Recommended use |
|---|---|---|---|
| Avansa 300 W | 300 W | cca 7-9 Ah | Single circulation pump |
| Avansa 500 W | 500 W | cca 7-9 Ah | Boiler + pump (typical house) |
| Avansa 500 W + battery 46Ah | 500 W | 46 Ah | Boiler + pump, long outages |
| Avansa 700 W | 700 W | cca 9-12 Ah | Boiler + pump + regulation |
| Avansa 1050 W | 1050 W | cca 12-17 Ah | Multiple circuits, cascade, reserve |
How power relates to backup duration
Power output of the source and battery capacity are two different parameters that are often confused. Power (in watts) indicates how much energy the source can deliver at a given moment - i.e., whether it can "start" the connected appliances. Battery capacity (in ampere-hours, Ah, convertible to watt-hours, Wh) indicates how long the source can deliver energy at a given load. A simple physical relationship applies: the operating time (in hours) equals the battery capacity (in Wh) divided by the actual power consumption of the connected appliances (in W).
For example, with a battery capacity of approximately 90 Wh (typical small battery in basic models) and a load of 150 W, the source will theoretically last about 35 - 40 minutes, and realistically about 30 minutes after accounting for the inverter efficiency (usually 85 - 90%). In contrast, with a 46 Ah battery (i.e., approximately 550 - 600 Wh in a 12V system) and the same load of 150 W, the real runtime is several hours, which is a crucial difference during longer power outages, which are not uncommon in rural areas.
The relationship between load and runtime is not linear - as the load increases, the runtime decreases faster due to the drop in inverter efficiency at higher loads and due to the characteristics of lead-acid battery discharge. The following curve graphically illustrates this relationship:
This curve is the reason why the simple rule "double capacity = double runtime" does not apply under high load. At low load (for example, only a circulation pump without a boiler), the ratio is more favorable. At high load (boiler with a fan at startup), the runtime is significantly reduced. For a detailed calculation of the specific runtime in your case, I recommend consulting the topic "How long will the backup power last during a power outage," where the calculation process is explained step by step.
Why the output voltage waveform is also important, not just watts
When comparing power outputs, it is also worth mentioning the quality of the output signal. Most modern circulation pumps (especially electronically controlled ones with frequency inverters) and the electronics of condensing boilers are sensitive to the shape of the output voltage. Power sources with a clean sine wave (pure sine wave) are compatible with almost all types of boilers and pumps without the risk of the electronics reporting errors or behaving incorrectly. With cheaper power sources that have a modified sine wave (a modified square wave), overheating of pump motors, incorrect fan operation, or error messages on the boiler display can occur. The Avansa range is designed to ensure that the output waveform meets the requirements of standard home boilers, which is one of the reasons why this range has proven itself in practice, even with more sensitive condensing boilers from brands such as Viessmann, Vaillant, Buderus, or Junkers.
Practical scenarios from everyday installation practice
Scenario 1: Apartment in a panel building with a separate circulation pump
When backing up only a separate circulation pump (for example, in district heating, where only the circulation pump is backed up, not the heat source), in most cases, the Avansa 300 W model is sufficient. The actual consumption of the pump, 40 - 70 W, leaves enough reserve, and the battery is enough to cover a typical short-term power outage lasting several minutes.
Scenario 2: Family house with a gas condensing boiler
This is the most common case in my practice. A boiler with a power consumption of approximately 100 - 130 W in operation plus a circulation pump of 50 - 80 W gives a total of around 150 - 210 W. The Avansa 500 W model is most often recommended here, as it provides a comfortable reserve even during startup peaks and is not oversized (and thus unnecessarily expensive) compared to the actual need.
Scenario 3: A countryside house with frequent and longer outages
In areas where outages last several hours (older overhead lines, storms, disasters), I recommend the model Avansa 500 W + battery 46Ah. The power remains the same as in the basic 500 W model, but the actual runtime is extended from minutes to hours, which in practice can mean the difference between a turned-off heating system and its continuous operation during the entire storm or line failure.
Scenario 4: A house with two heating circuits and multiple pumps
In systems with floor and radiator circuits, where two circulation pumps operate simultaneously with the boiler and possibly also a circulation pump for hot water, the consumption easily climbs to 250 - 350 W continuously, with short-term peaks exceeding 400 W. In this case, the Avansa 700 W model is appropriate, as it provides sufficient reserve without the device operating continuously at the edge of its capabilities.
Scenario 5: Boiler cascade or combination with a heat pump
In more complex systems, where it is necessary to back up multiple devices at once - for example, two boilers in a cascade, a control unit, multiple circulation pumps, and expansion automation - the most powerful model Avansa 1050 W is suitable. In this case, it is worth making a precise list of all the consumers and their power consumption even before purchasing, ideally following the procedure in the topic "How to determine the boiler and pump consumption for selecting a backup power source."
How the connection works and what affects the power of the power source during installation
Connecting the backup power source is basically simple - the source is connected between the socket of the electrical grid and the consumer (boiler, or a distribution panel with a circulation pump). In the event of a power outage in the grid, the source automatically switches to battery mode within a few milliseconds (usually under 10 ms), which is fast enough that the boiler's control electronics will not register it as an outage.
With higher power models (700 W and 1050 W), it is also important to consider that the incoming cable and the socket to which the source is connected must be able to handle the corresponding current draw, although at these power levels, it is still within normal values for a standard household socket of 230 V/16 A. The exact step-by-step connection procedure, including recommendations for the placement of the source (dry space, sufficient ventilation, distance from heat sources), can be found in the topic "Installation and connection of a backup power source to a boiler."
Internal construction of the power source and why it affects the actual power
The power stated on the label is always the result of the interaction of three main components inside the device: the battery, the charging circuit, and the inverter (DC/AC converter). The quality and dimensioning of the inverter determine what peak load the source can handle at the start of the pump motor, while the quality of the charging circuit determines how quickly the battery can be recharged after an outage and how long its lifespan will last with repeated cycling.
That is why more powerful models in the range (700 W, 1050 W) usually also have more robust batteries and more powerful inverters – it is not just about a higher number on the box, but about the overall dimensioning of all internal components so that they can handle the declared power over the long term without overload or overheating.
Most common mistakes when selecting by power
Over the years in sales and service, the same mistakes when selecting a power source repeat practically every time:
- Underestimating starting currents – the customer calculates only the boiler's operating power, but forgets about the short-term peak during the fan or circulation pump startup, which can be 2–3 times higher than the operating value.
- Selecting by price instead of power – a cheaper 300 W model bought for a system with two pumps gets overloaded, and the battery and inverter lifespan is significantly shortened.
- Ignoring the need for longer runtime – in areas with long power outages, it is worth considering from the beginning a variant with a larger battery, for example Avansa 500 W + battery 46Ah, instead of later purchasing an external battery.
- Forgetting about future expansion – when planning the installation of another circuit or replacing the boiler with a cascade, it is better to choose a higher power model right from the start.
- Incorrect placement of the power source – even a properly dimensioned power source can have a shortened battery life if placed in a space with high temperatures (for example, right next to the boiler), which relates to the topic of Maintenance and battery lifespan of the backup power source.
How power relates to price and return on investment
The price difference between the 300 W and 1050 W models is usually much lower than the difference in risk you take with an underdimensioned power source. An underdimensioned power source either automatically shuts off (and the system remains without backup exactly when it is needed most) or, in the worst case, leads to repeated inverter overloads, which shortens its lifespan and can lead to premature failure outside of warranty. An investment in a more powerful model of one class is therefore usually worth it, especially if we consider that the price of a boiler that could be damaged by a sudden power outage during operation (for example, due to a frozen system in winter) is several times higher than the price difference between the various Avansa models.
Summary of recommendations by type of installation
| Type of installation | Recommended model |
|---|---|
| Single circulation pump | Avansa 300 W |
| Standard family house, boiler + pump | Avansa 500 W |
| Area with long outages | Avansa 500 W + battery 46Ah |
| Two circuits, multiple pumps | Avansa 700 W |
| Boiler cascade, complex system | Avansa 1050 W |
Frequently asked questions about Avansa power comparisons
Is higher power always better, even if I don't actually need it?
Higher power provides a greater safety margin, but it is not necessary to always reach for the most powerful model. Overdimensioning is not harmful in terms of functionality, but it unnecessarily increases the purchase price. I recommend calculating the total power of all backed-up devices precisely and adding at least a 30–50% reserve to account for starting currents.
Can I later replace the battery with a larger one if the 500 W model is not enough for longer outages?
This is possible with some models, but you must verify the compatibility of the specific battery type and voltage. A simpler and more reliable solution is to choose from the start a variant with a larger capacity, for example Avansa 500 W + battery 46Ah, which has the same power as the basic version but significantly longer runtime.
How can I find out if the 500 W model will be sufficient in a few years if I add another circuit?
If you know you plan to expand the system in the future (another pump, boiler cascade), I recommend choosing a model with higher power right now, for example Avansa 700 W or 1050 W, since buying a second power source later is less practical than a single central solution with sufficient reserve.
Will the power difference be noticeable in terms of noise or device size?
More powerful models are usually slightly larger due to the larger transformer/inverter and larger battery, but the noise during normal operation is low in all Avansa models, as cooling is primarily passive or handled by a quiet fan that is only activated at higher loads.
What happens if I connect devices with higher power than the power source's rated power?
The device usually activates an overload protection and disconnects the output to prevent damage to the inverter. Therefore, it is important to account for starting currents when selecting, not just the steady-state operating power – more details on this topic can be found in the article Common faults of backup power sources for boilers.
Can a lower power model be used as a temporary solution and later replaced?
Yes, but you must consider that even in temporary operation, overloading shortens the lifespan of components. If it is clear that the actual consumption exceeds the rated power of the selected model, I recommend investing in a higher class right away instead of dealing with premature replacement after a few months of operation.
Conclusion
The comparison of power levels in the Avansa range shows a clear trend – as the wattage increases, so does not only the ability of the power source to serve more devices at once, but also the battery capacity and robustness of internal components. When selecting a specific model, it is most important to base your choice on the real total power of all devices you want to back up during an outage, add an appropriate reserve for starting currents, and also consider how long outages are common in your area. If you are unsure about the exact consumption of your boiler and pump, I recommend reading the topic What power backup source do I need for my boiler, where the calculation process is described in more detail, or contacting technical support directly, who can help you choose the exact model from the range of backup power sources for boilers and circulation pumps precisely according to your actual installation.
Do you have a question about this topic?
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