Low Temperature Air Source Heat Pumps LTASHP
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. Low-Temperature Air Source Heat Pumps (LTASHPs) describe standard ASHPs running at output or flow temperatures with a maximum of around 55°C.
Low Temperature Air Source Heat Pumps (LTASHPs) are suitable for systems such as underfloor heating or larger surface radiator systems. Other systems that achieve slighter warmer temperatures of around 65°C might be referred to as Medium Temperature Air Source Heat Pumps (MTASHPs). Finally High-Temperature Air Source Heat Pumps (HTASHPs) which tend to use more robust components and specialised refrigerants (such as R290/R32), as well as dual compression systems can achieve hotter temperatures than standard ASHPs in the region of 70-80°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.
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