What Is a Heat Pump and How Does It Work?

A heat pump is an electrical device that extracts heat from one place and transfers it to another. The heat pump is not a new technology; it has been used in Canada and around the world for decades. Refrigerators and air conditioners are both common examples of this technology.

Heat pumps transfer heat by circulating a substance called a refrigerant through a cycle of evaporation and condensation. A compressor pumps the refrigerant between two heat exchanger coils. In one coil, the refrigerant is evaporated at low pressure and absorbs heat from its surroundings. The refrigerant is then compressed en route to the other coil, where it condenses at high pressure. At this point, it releases the heat it absorbed earlier in the cycle.

Refrigerators and air conditioners are both examples of heat pumps operating only in the cooling mode. A refrigerator is essentially an insulated box with a heat pump system connected to it. The evaporator coil is located inside the box, usually in the freezer compartment. Heat is absorbed from this location and transferred outside, usually behind or underneath the unit where the condenser coil is located. Similarly, an air conditioner transfers heat from inside a house to the outdoors.

The heat pump cycle is fully reversible, and heat pumps can provide year-round climate control for your home – heating in winter and cooling and dehumidifying in summer. Since the ground and air outside always contain some heat, a heat pump can supply heat to a house even on cold winter days. In fact, air at –18°C contains about 85 percent of the heat it contained at 21°C.

An air-source heat pump absorbs heat from the outdoor air in winter and rejects heat into outdoor air in summer. It is the most common type of heat pump found in Canadian homes at this time. However, ground-source (also called earth-energy, geothermal, geoexchange) heat pumps, which draw heat from the ground or ground water, are becoming more widely used, particularly in British Columbia, the Prairies and Central Canada.

Efficiency Terminology
The efficiency ratings for different types of heat pumps use different terminology. For example, air-source heat pumps have seasonal heating and cooling ratings. The heating rating is the HSPF; the cooling rating is the SEER. Both are defined above. However, in the manufacturers' catalogues you may still see COP or EER ratings. These are steady-state ratings obtained at one set of temperature conditions and are not the same as the HSPF or SEER ratings.

Earth-energy systems use only COP and EER ratings. Again, these ratings only hold for one temperature condition and cannot be directly used to predict annual performance in an application. In the section of this booklet titled "Major Benefits of Earth-Energy Systems", the COP ratings were used in a calculation to estimate HSPFs in different regions across Canada. HSPFs are not normally used to express the efficiency of earth-energy systems, but are used here to enable a comparison with air-source heat pumps.

Benefits of using Heat Pump Water Heaters
Heat Pump Water Heaters provide a very suitable and efficient alternative to the regular water heater. Here are a few benefits of using Heat Pump Water Heaters-

  • 1. It can heat up large volume of water at a time. They come in different varieties having capacities upto 200 Litres (or more sometimes).
  • 2. These are highly cost effective as they consume lesser electricity to heat up the same volume of water than a regular water heater.
  • 3. They do provide service for a long time. Meaning? They have a long life.
  • 4. They can act as coolers as well as they tend to cool up the place where they are installed.
  • 5. Heat Pump Water Heaters are absolutely safe.
  • 6. The installation requires little effort. Also they are easy to maintain.

Heat Pump Water Heaters are a tremendous innovation in the field of appliances, especially the ones which are light on the electricity consumption. So if you want to spend lesser than what you pay currently for using warmer water, heat pump water heater is the thing which you would not want to miss out on.