DX small air source heat pumps have been a common feature of the heating of commercial buildings for over two decades, in the form of splits and multi VRF systems. These systems tend to be either individual units (typically up to 12kW), or small capacity multiple fan coil units connected to outdoor DX condensing unit modules with capacities typically under 130kW. They work well but the building often still needs boilers to produce high temperature direct hot water.
When it comes to larger buildings, the four-pipe fan coil is prominent with heating coming from a boiler and cooling being provided by a chiller. Cooltherm has been at the forefront of large scale reversable air to water and water to water heat pumps for the last decade. However, achieving the high temperatures required to replace a boiler ‘like for like’ was just beyond the reach of the F-gas refrigerants which are currently being phased down. 60°C is typically the peak temperature that can be reliably achieved in constant operation.
Cooltherm has been working with Geoclima to develop an industrial/commercial range of heating only, reversible and four-pipe (simultaneous heating and cooling) air source units which operate on ultra-low global warming potential refrigerant R1234ze (6). Our cascade systems can develop water temperatures of 70°C at a COP of 4:1 in a -5°C ambient, which outperforms typical boiler systems in the efficiency stakes.
The range spans from 20kW to over 400kW and all multi-circuit machines feature intelligent defrost which maintains a constant positive heat output even during the unavoidable defrost cycle.