High Temperature Air Source Heat Pumps HTASHP
Air source heat pumps (ASHPs) use the external air as a heat source to provide heat for buildings, there are effectively three types of ASHP, differentiated by the output temperatures they can achieve; high, medium or low temperature. High-Temperature Air Source Heat Pumps (HTASHPs) tend to use more robust components and specialised refrigerants (such as R290/R32), as well as dual compression systems to achieve hotter temperatures than standard ASHPs.
Output or flow temperatures with a maximum of 55°C are considered Low Temperature Air Source Heat Pumps (LTASHPs) and most suitable for systems such as underfloor heating or larger surface radiator systems. Medium Temperature Air Source Heat Pumps (MTASHPs) run at a maximum of around 65°C, whilst High-Temperature Air Source Heat Pumps (HTASHPs) can achieve temperatures as high as 80°C.
All ASHPs work by running a refrigerant fluid in heat exchanger coils through the external air. The fluid ‘absorbs’ heat from the air and boils, even at temperatures below 0° C (although the coefficient of performance (COP) decreases with lower temperature). The gas is then compressed, which further increases its temperature or dual compressed for high temperature systems and passed into heat exchanger coils, where it condenses, releasing its latent heat. The process then repeats. It is the same process that is used to extract heat from a fridge and can be used domestically or commercially and some systems can also be used to extract heat from buildings to provide cooling.
[edit] Related articles on Designing Buildings
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