What is a heat pump
Tuesday 17 May 2022
A heat pump is part of the house heating network. It is mounted outside the house and, like a reverse air conditioner, draws heat from outside to inside. It uses far less electricity than most other heating systems and can be connected to solar panels. Because they do not burn gas and require very little electricity, they are also very efficient. This is why they have become increasingly popular with homeowners and housing associations. Here we explain exactly what a heat pump is, what it does and how it works. If your pump is broken, here is what you need to do to repair it.
How does a heat pump work?
A heat pump does not create heat. There are various types of these pumps and they all work in a slightly different way. However, the underlying principle is always the same: heat exchange. This means that the device moves heat from one place to another. Heat naturally flows from hot to cold, so as long as the pump is colder than the outside air, it will attract heat from the outside air. To make this process more effective, a compressor is used and the pump uses coolant. The process is as follows:
Coolant flows in pipes between the outdoor and indoor units. The coolant is always colder than the outside air, even when it is freezing. These liquids evaporate even at very low temperatures.
When the liquid flows through the outdoor unit, it is warmed up by the outside air. Even if it is cold outside, the fluid will warm up because the outside air is warmer than the coolant. This difference in temperature is what is later released into the house.
In the indoor unit, the incoming fluid is pressurised in a compressor. Fluids under pressure increase in temperature, boil and even condense. As a result, even a small difference between the normal temperature of the coolant and the outside temperature becomes warm enough to heat your house.
The warm, condensed refrigerant then travels through pipes to various places in the house, for example, to heat the house or to provide hot water.
Once back in the indoor unit, the coolant is cooled by reducing the pressure and once it has liquefied it is pumped back to the outdoor unit. This makes the process complete and continuously active.
Heat pumps are less effective when it is freezing hard and in very cold climates. But in recent years the technology has improved a lot. Especially with the use of coolant that remains liquid when it freezes, the pump has become much more reliable.
Heat reservoir: insulating your home
The heat that is drawn in from outside is stored in a heat reservoir. For the heating network of your house, this is simply the house itself. As long as the house is cooler than the heat extracted by the pump, the coolant will continue to lose its heat to the house. This also means that, if your house is already heated in another way, the pump is running for nothing. Although a heat pump is efficient, it is not as effective as a central heating boiler. It is therefore important that the heat reservoir is well insulated against temperature fluctuations. This can be determined as follows:
Lower the temperature of your central heating boiler to 50 degrees in winter.
If your house remains comfortably warm, then it is sufficiently insulated.
If you get cold, you should first insulate the roof and/or cavity walls.
What types of heat pumps are there?
Air-water pump: these take heat from the outside air and transfer this heat to the heating system in the house.
Water-water pump: These pumps extract heat from groundwater. To do this, groundwater is pumped up from one well and the heat extracted from it. The cooled water is then returned to the ground through another well. With these pumps, it is important that the pump is used as an air conditioner in the summer in order to maintain the groundwater level.
Soil-water pump: The heat is extracted from the earth by these pumps. Pipes through which coolant flows are drilled vertically, deep into the ground. The pipes must be deeper than the frost layer in winter for maximum results.
Hybrid pump: these are air-water pumps that are connected to the central heating boiler. The pump does most of the work and the boiler assists if necessary. This is the most common pump and requires the least adjustment to the existing heating network of your home.