We believe in heat pumps with natural refrigerants. Propane (R290) is an excellent refrigerant. It has an extremely low contribution to Greenhouse Warming, much unlike other – chemical – refrigerants. Propane is flammable, but the quantities we use in domestic heat pumps are quite small.
The first propane heat pump we built in 2017 was a 4 kW booster heat pump. It contains just 150 grams of propane. It uses a single speed scroll compressor, and an internal heat exchanger for improved efficiency.
The second propane heat pump we have built is a 9 kW air to water model. This model contains 750 grams of propane. It has a variable speed scroll compressor, and an internal heat exchanger. The most remarkable item however is the microchannel evaporator which is used to minimize the propane charge. This heat pump was completed in 2019.