Even the most cutting-edge and high-tech heating technology cannot be self-sufficient. The presence of control sensors, control automation, fans and units for extracting and forcing air mass makes the heating boiler dependent on electricity. These features have not bypassed solid fuel units, which many are accustomed to considering as completely autonomous heating devices. Any failures in the operation of the power supply system have an extremely negative impact not only on the efficiency of the heating system, but can also cause boiler equipment to fail. This is especially unpleasant at the height of winter, when the greatest load falls on the autonomous heating system.

An uninterruptible power supply for a solid fuel boiler will help solve the problem of constant power supply to heating units — a device that is equipped today with almost any household equipped with electrical appliances for various purposes.

What is a UPS? Basic technical requirements for devices

The abbreviation UPS stands for uninterruptible power supply, in English UPS. The device is designed to provide for a certain period of time the power supply of any device, device or mechanism for normal operation. Uninterruptible is a kind of fuse against unauthorized shutdowns of centralized power supply, which can lead to failure of volatile equipment and loss of its functionality.

An uninterruptible power supply device is equipped with almost any modern technology, which in one way or another is structurally connected with electricity. In each individual case, for the autonomous supply of equipment with electricity, its own type of uninterruptible power supply is used, which has certain parameters and specific characteristics.

For example: A UPS for office equipment has a certain capacity and output voltage, while an uninterruptible power supply for home appliances, including heating appliances, is designed for other electrical parameters. In this case, the device has its own design features.


Let’s start in order. What distinguishes an uninterruptible power supply for a solid fuel boiler, a boiler, from similar devices that are equipped with other electrical appliances.

1. An uninterruptible power supply for heating units must have output voltage parameters identical to those of electrical equipment that is equipped with solid fuel boilers. The sinusoidal voltage waveform is characteristic of solenoid valves, ensures the operation of pumps and blowers. Only in this case, when the current in the network disappears, the electrical devices of the heating unit will work in normal mode.

Important! It is not recommended to use a UPS designed for computer equipment to ensure the operation of the boiler. The reason is that such devices do not give a sinusoidal voltage, on the contrary, office uninterruptible power supplies give a rectangular meander with zero.

2. An uninterruptible power supply device for solid fuel heating units must ensure a sufficiently long operation of heating equipment. In other words, the battery capacity must be significant in order to ensure the autonomous operation of boiler equipment during a power outage. Office devices are designed for a maximum of 10-15 minutes of power, calculated only to bring computer equipment out of operation without failure.

3. Any heating boiler, solid fuel devices are no exception, are sensitive to voltage drops. When turned on, the uninterruptible power supply must receive a sufficient amount of electricity from the batteries, sufficient to provide voltage with the same phase as in a centralized network.

4. In the event of power outages and outages, the transition of the solid fuel boiler to power supply from the UPS should not exceed 10 milliseconds.

Types of uninterruptible power supplies for solid fuel heating equipment


Any autonomous heating system is equipped with an uninterruptible power supply. Depending on the type and type of boiler equipment, an uninterruptible power supply of the appropriate type is installed. To date, in practical terms, three types of UPS are used:

  • off-line devices;
  • devices Line — interactive;
  • double converters, On-line systems.

Each model of the device differs in its design and principle of operation. Let’s consider in more detail.
Off-line uninterruptible devices are the most common devices. They have a simple design and affordable cost. The work is based on the following principle:

  • power failure in the network, voltage drops trigger the UPS-battery circuit. The voltage that appears returns the device to normal mode — power from the mains. The time for switching the device to battery power and vice versa is no more than 15 milliseconds.

The product consists of traditional elements: an inverter that converts the direct current in the battery into electricity with a voltage of 220V. Off-line models work from the mains with a voltage of 170-270V. The main difference of this type is that they do not have a voltage stabilizer, so the output voltage of such uninterruptible power supplies is equivalent to the mains voltage.

On a note: In case of unstable operation of the power grid, the uninterruptible switch constantly switches either to the battery or to the centralized power supply network. This mode leads to a rapid reduction in the life of the device.

Another type of UPS used in practice is the interactive uninterruptible power supply. These devices are equipment that occupies an average niche, both in terms of functionality and in terms of cost. The principle of operation of interactive autonomous power supplies is similar to that of off-line inverters. The only difference is the presence of a voltage stabilizer. Due to their design, such devices are more reliable and safe to use. Each model in this case is designed to interact with the central power supply network 170-270V.

The last, third type of uninterruptible power supplies is a device operating in live time, on-line. In these devices, there are practically no disadvantages inherent in the other two types of UPS. The main highlight of these devices is as follows:

  • The UPS converts the input AC to DC voltage in real time, regardless of its parameters and characteristics. In the future, the direct current is already converted into a stabilized, alternating voltage.

Such models have an undeniable advantage, besides, on-line UPSs work effectively in tandem with generator sets. This feature is very relevant in situations where there is no centralized power supply for a long time, the operation of electrical appliances depends on the functionality of autonomous mini-power plants.

From a technological point of view, the design of an on-line UPS is quite complex. Accordingly, these products are expensive. The expediency of using such equipment is justified in those conditions when boiler models that are sensitive to power surges are installed.

Based on the foregoing, certain conclusions can be drawn. Most often, for the normal operation of heating boilers operating on coal, wood and other types of solid fuels, it is enough to acquire an active uninterruptible power supply or an off-line device. When in a country house or in the private sector, due to frequent power outages, the main load falls on diesel generators, the best option would be to buy an on-line uninterruptible power supply.

The choice of an uninterruptible What to look out for

The choice of an uninterruptible power supply for solid fuel boilers is influenced by a variety of factors. First of all, it is necessary to determine the power of the heating unit, the functionality of the heating system, which will be provided if necessary by the UPS.

In many ways, not only the type of uninterruptible power supply, but also the type of battery depends on the power of the boiler. The capacity of the battery determines the duration of the operation of the uninterruptible power supply. The table shows the parameters of the equipment corresponding to a particular heating device.

boiler power,


fifty 100 150 200 300 400 500
Battery capacity (battery) Am/h
65 6.8 6.8 3.9 2.2 1.5 1.1 0.7
100 25.7 12.2 7.2 5.4 3.1 1.8 1.4
150 37.9 18.1 12.1 8.1 5.4 3.4 2.1
250 49.2 24.6 16.0 12.0 7.3 5.5 3.8

The choice of the type of UPS is influenced not only by the power of the heating device, but by the number of additional units powered by electricity. This should include fans, heating system pumps, control devices, alarms and adjustments.

The optimal choice of UPS also depends on the quality of the centralized power supply, which includes the frequency of outages, the duration of outages, and the range of voltage drops in the network.

Important! When analyzing the capabilities of a UPS, do not forget about the inductive load. Mechanisms and electrical appliances that are installed on the equipment of heating equipment give a significant induction load to the internal electrical network. When fans or circulation pumps are started, the load in the network increases by 3-6 times. Modern models of uninterruptible power supplies are able to withstand short-term overloads, however, the best option would be to buy a UPS with a power reserve of 25-30%.



Ultimately, when buying a device, you should pay attention to its autonomy. The duration of the UPS is directly dependent on the capacity of the battery. Accordingly, the larger the battery capacity, the higher the cost of the device. As a rule, two types of stationary batteries are used to operate the UPS in an autonomous heating system: AGM or GEL. These are devices made on the basis of lead-acid cells.

GEL batteries have a large capacity and are designed for heavy loads. In addition, this type of battery has a significant resource of charge and discharge cycles.

On a note: for the operation of solid fuel boilers (any heating devices), car batteries should not be used. The reason is the chemical composition of the oxidizing agent. Using a UPS to operate an autonomous boiler involves installing the device together with the battery in the boiler room. The evaporation of hydrogen during the operation of heating equipment can eventually lead to the formation of an explosive hydrogen-oxygen mixture.

The proposed types of batteries for the operation of uninterruptible power supplies have an undeniable advantage — they do not need constant maintenance.

The video shows how to select an uninterruptible power supply for solid fuel boilers.


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