Kensa Heat Pumps has created a new Hybrid ground source heat pump to add to its British-made product range, addressing cost concerns and peak heating and hot water demands of larger new builds and well insulated homes.
The Hybrid ground source heat pump is available in 15kW and 21kW single phase models; some of the largest single phase ground source heat pumps available on the market.
Kensa’s twin compressor Hybrid heat pump harnesses the properties of two separate refrigerants in its compressors to deliver heat outputs similar to those provided by Kensa’s Standard models, along with hot water temperatures typically produced by their High Temperature models. This blended design allows customers to enjoy both defining benefits of Kensa’s product ranges in one affordable unit.
The motivation for the creation of the Hybrid was capital cost, as Guy Cashmore, Technical Director of Kensa Engineering continues: “The properties of different refrigerants can meet specific needs, but each come with a compromise.
"For example, Standard Kensa models use R407C refrigerant to provide space heating outputs but as a result hot water temperatures are compromised to approx 50°C. The introduction of R134a refrigerant transforms the Standard into a High Temperature model, allowing the unit to produce hot water up to 60°C, but this reduces its space heating output. So to achieve space heating demand and hot water up to 60°C, traditionally we supplied a High Temperature model with a larger compressor to allow for the de-rating in the systems space heating output, which regrettably cost the customer more money.
“The Hybrid provides both space heating (up to 50oC) and hot water (up to 60°C) by using both refrigerants, one in each of the unit’s compressors. This removes the need to increase the compressor size of the unit to compensate for any de-rating in heat output associated with pure High Temperature refrigerant, and as a result saves the customer money.”
To deliver space heating and hot water the first compressor in Kensa’s Hybrid uses Standard temperature (R407C) refrigerant, whilst the second compressor uses High Temperature (R134a) refrigerant.
Both compressors work together to deliver the space heating. When producing hot water, both compressors work together initially, but once the hot water gets hotter than the Standard temperature compressor’s return temperature set point, this compressor turns off. The compressor with the High Temperature refrigerant then takes over on its own to provide an extra 15°C to the hot water cylinder.
The Hybrid also usually removes the requirement to periodically heat the cylinder with an immersion heater to pasteurise the hot water.
