Situl Mistry, product manager of SPC's heat pumps and renewables division, discusses the evolution of high temperature air source heat pumps for use with energy efficient heat emitters.
The new Generation of high temperature air source heat pumps is capable of providing hot water delivery temperatures of up to 65°C for heating and 90°C for domestic hot water.

Heat pumps have traditionally been associated with medium or low temperature hot water production and therefore only deemed suitable for low temperature heat emitters such as under-floor heating systems.

The new range of high temperature heat pumps opens up the possibility of combining heat pumps with more effective/efficient heating systems such as radiant panels.
Radiant panels and radiant sails provide much flexibility due to their modularity and low thermal inertia. Unlike under-floor systems these emitters respond quickly and have a rapid heat up time.

Delivery temperature

Radiant panel outputs increase almost linearly with mean water temperature. This means their outputs are directly linked to the heat pump's delivery temperature. The new generation of high temperature heat pumps include control algorithms for setting the flow temperature on a weather compensated basis. As the ambient temperature increases, the heat load is reduced and the flow temperature falls. Unlike conventional generators, the efficiency of operation of the heat pump system will increase at part load giving seasonal COP values close to 4. Designing the whole system of generators and emitters is key to maximising the energy benefits of heat pump systems and should transcend conventional 'mix and match' approaches.

The increased delivery temperatures and COP values of the latest generation of air source heat pumps also opens up the possibility of retrofit applications; a conventional radiator emitter system will often be capable of offsetting the required heat losses when combined with a high temperature air source heat pump.

The SPC Climaveneta HT range of air source heat pumps provides both heating and domestic hot water at up to 65°C. This eliminates the need for an electrical immersion in the water tank which would otherwise be required to boost the temperature of the DHW and prevent the risk of legionella. Modular sizes of up to 100kW are available and can be controlled by a centralised controller, whose primary function is to modify the operation and performance of each module to ensure a balanced output in relation to the demand and ambient temperature.

The SPC Itomic heat pump unit uses CO₂ refrigerant to produce hot water at up to 90°C for domestic and sanitary use. This system provides an ideal direct replacement for existing sanitary and hot water boilers for applications where high volumes of hot water are required. By running the system overnight you can take advantage of off peak electricity tariffs enabling you to produce a low cost and low carbon store of domestic hot water.

Hybrid systems can be designed to incorporate both common refrigerant-based heat pumps whose high COP levels are ideal for an energy efficient heating system along with CO₂ systems for low cost DHW production.