Is an air-source system a viable option?
A. Air-source is much easier and cheaper to install. But it does not promise very high energy efficiencies for year-round heating in the UK, particularly in the North. The main reason being that the efficiency drops when you need most heat. A back-up from a boiler at such times is usually required. Ground source, by contrast, maintains a constant heat output unaffected by the daily temperature changes above. Smaller air systems may give reasonable overall results if used alongside a boiler, but only if used when air temperatures are not too cold. Air source units usually have a shorter life since they have to work out in the elements.
