 Efficiency (COP = Coefficient Of Performance) is an expression used to describe the heat pump’s capacity to produce heat in relation to the energy required to extract it. If a certain heat pump has a COP 3 it means that it can produce three times more heat energy than the electrical energy it consumes. A unit of 1 kilowatt electricity results in 3 kilowatts of heat energy. In this example, your net exchange is two thirds.
But that is not the entire story. The efficiency is not constant. It varies with the outdoor temperature, or better said with the difference between the indoor and outdoor temperatures. The greater the difference, that is the colder outside, the less efficient it will be. When you compare the efficiency of different heat pumps, you should bear in mind that the efficiency is often audited in a specific operating condition, for example 0 °C/35 °C. That operating condition means that the incoming brine is at 0 °C and that the heat pump gives 35 °C to the heating system. The installation’s circulation pumps are often not included in the efficiency calculation either. In other words, operating conditions of no interest to you as a consumer.
It is much more interesting to know what efficiency a heat pump can achieve averaged over the course of year. Winter and Spring. Day and Night. This value is called annual efficiency. The difference between different makes of heat pump is often very large.
The market for air heat pumps is quite complicated. The price differences are often very large, which reflects the different performances and functions. Be sure to check how effective the air heat pump is when it is really cold outdoors. A good heat pump should be able to retrieve energy from the air down to a temperature of -20 °C.
One way of evaluating the service life of various makes is to look at the insurance company damage statistics. These are available at the website www.folksam.se Enter the word “värmepumpar” in the search function. |
