Both work by using refrigerant phase change and mechanical compression of a substance to provide temperatures adequate to work with domestic and commercial heating and hot water system. The difference lies with how each of these two systems gathers the required energy from the environment.
All heat pumps work by changing a refrigerant from a liquid to a gas and back to a liquid again in a closed refrigeration cycle. It is the ambient temperature taken either from the ground or air that boils the refrigerant in the first instance.
Ground source heat pumps do this by circulating a glycol/water mix through a network of collector pipework in the ground. As they are 1m deep the temperature does not greatly fluctuate, therefore ground source heat pumps tend to be more efficient throughout the year when compared to air source heat pump systems.
By comparison, air source systems draw the air over an evaporator using a fan. The ambient air temperature is then transferred directly to the refrigerant which is then boiled and ready to be mechanically compressed to generate the high grade heat required to pass onto the heating and hot water systems. However, the air temperatures in the winter are much colder than at 1m below ground level. Which is one of the reasons why air source heat pumps suffer a drop off in output and require slightly more electricity to run over an average year. The other is that there is moisture in the air. During the winter as heat is extracted from the air by the heat pump, some of the moisture may condense turning into ice on the unit. The heat pump has to monitor the build-up of ice and periodically reverse its operation to melt the ice. This takes energy, and is something a ground source heat pump does not have to do.
Air source heat pumps offer a very good heat source for summer use of outdoor pools. Usually the air temperature is high during this time of the year resulting in fantastic efficiency for air source systems and substantial fuel savings.
It is therefore critical that you assess the load required of your project before you chose which technology you opt for, as both ground and air source have their limitations.
If you would like more information on which type of heat pump is right for you, contact us today on 01293 821 345.
