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Heating a house with an air-to-air heat pump

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Heating a house with air is a technology that excludes intermediaries in the transfer of heat. With the use of a heat pump, the efficiency of the system increases by 2–3 times, but are such systems applicable in the realities of the Russian climate? Today we will talk about air pumps and the device of heating systems with their use..

Heating a house with an air-to-air heat pump

How it works and weaknesses

Air heat pumps can serve as both the simplest means of local heating, and be the core of a centralized heating system. Their main advantage is complete independence from other utilities at home, with the exception of the electrical network. Thus, the installation of an air heating system is possible at any stage of construction, and even after its final completion..

The refrigerant does most of the work inside heat pumps. This substance has a very low boiling point, down to -30? С. During evaporation, the liquid absorbs energy, during condensation, it releases it into the external environment. Refrigerant vapors cannot naturally condense; for this, a compressor is switched on, increasing the pressure and “squeezing” the temperature. Thus, the outside air is supercooled, for example, from -5 to -15? C, and the remaining delta of 10? C returns to the inside of the house in the form of useful heat.

Air-to-air heat pump device Air-to-air heat pump device: 1 – outside air; 2 – external heat exchanger; 3 – outdoor block; 4 – compressor; 5 – indoor unit; 6 – warm internal air; 7 – internal heat exchanger; 8 – thermostatic valve

Of course, everything is not as rosy as the manufacturers of heating equipment describe. The real effectiveness of the system is limited by two factors:

  1. The boiling point of the refrigerant defines the limit at which the heat pump is in principle capable of operating. Most devices are capable of generating at outdoor temperatures from -5 to -15 ° C, the most expensive (Zubadan) operate down to -25 ° C. In complex heating systems based on heat pumps, an additional evaporator can be used in the outdoor unit.
  2. The conversion factor (COP) defines the ratio of the heat output to the applied electrical power. The real value of the coefficient is inversely proportional to the difference in air temperatures inside the building and outside. Thus, in severe frost, the performance of the HP is significantly lower.

Heat pump savings and scope

Any technology that is able to extract additional watts of energy in addition to the expended energy already implies significant savings. The only question is in the cost of the equipment and the time for which it will pay for itself.

It is easy to calculate: take the calculated indicators of heat loss at home, divide by the average COP value, taking into account the average temperature of the outside air during the heating season, and multiply the resulting power value by the cost of the type of energy carrier that could be used with a different type of heating.

Heating a house with an air-to-air heat pump

At a cost of about 3500-4000 rubles for each m2 of the heated area, air heat pumps have a payback period of about 20-30 years, which is twice the guaranteed service life of the equipment. However, one must always make allowances for the constant rise in energy prices and the potential for the development of new, more efficient refrigerants..

However, there are situations where the savings from installing a heat pump can be felt right away. For example, if the cost of supplying natural gas to a site is about 700-800 thousand rubles, the purchase of an alternative heating unit will provide lifetime savings literally from the first day of use. It can be argued that a gas boiler can be successfully replaced with an electric one, but the installed capacity of the city network is not always enough to replenish the heat losses of the house..

Heating a house with an air-to-air heat pump

It is also important to understand the difference between primary and secondary heating. Air heat pumps, designed to operate at positive outdoor temperatures, cost 2–2.5 times lower, and the savings and comfort from their use in the off-season are noticeable more than.

Centralized and spaced heating systems

The role of the air-to-air heat pump in domestic applications can be reduced either to heating individual rooms, when there is no special sense to “drive” the main heating unit, or to a complete re-equipment of the boiler room. In the latter case, an electric or gas boiler becomes a backup heating source, helping the heat pump to cope with extremely low temperatures or power outages..

Electric heating boiler

The local application of the heat pump seems to be more prudent. Why fence a complex heating system if local heating devices provide flexible climate regulation, and the breakdown of one of them will not cool the entire building? However, there are a number of arguments against this approach:

  1. It is very difficult to direct the heated air to the desired route. Many cold zones are formed, and it takes time to reach a constant comfortable thermal mode.
  2. The overall efficiency of several units is always lower than when installing one more powerful.
  3. Numerous outdoor units will spoil the appearance of the facade, and the internal ones will disturb the interior of the premises..
  4. There are limitations in the duration of the technical route connecting the outdoor unit with the indoor unit, which makes it difficult to heat rooms in the center of a large building.

Air-to-air heat pump indoor unit

A centralized heater based on an air-to-air heat pump requires laying a network of air ducts, which is especially difficult to accomplish with a monolithic type of ceilings and walls. But there are also advantages of such a system:

  1. You have complete control over the temperature and humidity in your home.
  2. There is a possibility of cleaning and disinfecting air.
  3. Full control over the ventilation inflow and exhaust helps to reduce heat losses associated with air exchange or use recuperators.
  4. Maintenance of one unit requires less time, effort and money.
  5. It is easier to organize work in extreme modes for one external unit. For example, it makes sense to turn on the additional heating of the outdoor unit at high negative temperatures, up to a fire nearby. Or, alternatively, you can set up an air preparation system on a soil heat exchanger.

Is it possible to do it yourself

Despite the technical complexity of heat pumps, they can be installed independently. More precisely, with your own hands you are free to carry out all the “dirty work”: laying technical pipelines and power networks, hinging indoor and outdoor units. The passport documentation for each specific type of heat pump contains comprehensive information about the conditions for installing the units, the slope, the length and permissible bends of technical routes.

Air-to-air heat pump installation

All that remains later is to invite a specialist who will check the correct installation of the system and ensure its correct commissioning. These works cannot be done by yourself: equipment is required for cleaning and de-airing the system, charging the refrigerant – in general, this process is quite technological and complex.

Air-to-air heat pump installation

It should be emphasized that the installation of such air conditioning systems is not done “overnight.” A detailed preliminary calculation is required, in particular, it is necessary to determine the class of equipment suitable for specific climatic conditions and calculate its sufficient power. Of course, district heating based on heat pumps creates even more difficulties in the design and coordination of work with construction contractors..

System durability and maintenance

Many may be scared off by the system’s operating life of 7-10 years, declared by the manufacturer. In practice, this figure is much higher, just a heat pump can lose performance over time..

This is primarily due to the gradual leakage of the refrigerant into the external environment and its contamination with moisture and other impurities. In this case, a fairly simple maintenance procedure is provided, which consists in cleaning the coolant and replenishing its concentration.

Heating a house with an air-to-air heat pump

Mechanical wear, such as a compressor or fan, is inevitable. However, a good heat pump allows for modular replacement of its constituent parts. The durability of the equipment is entirely determined by the conditions of its operation and the technical perfection of the system. Work at the limit, periodic icing of the outdoor unit and other violations of the normal operating mode – this is what must be excluded from the very beginning so that the equipment has time to fully pay for itself and at the same time bring the desired warmth and comfort from use to the house.

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Comments: 2
  1. Everly

    Can anyone share their personal experience with heating a house using an air-to-air heat pump? Is it cost-effective and efficient? How does it compare to other heating methods? Any advice or recommendations would be greatly appreciated!

    Reply
  2. Avery Carter

    Is heating a house with an air-to-air heat pump a cost-effective and efficient solution? Are there any specific factors or limitations to consider when using this type of system?

    Reply
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