A GROUND-SOURCE heat pump system is said to have has proved itself to be over 300% more efficient than a chiller/boiler combination in trials carried out by Mitsubishi Electric.
Since the beginning of this year, the company has been monitoring the inverter-driven City Multi WY Series VRF heat pump system in an installation at its headquarters in Hatfield.

The condensing unit is linked to a 'slinky' - a coil of plastic tubing buried horizontally in a 1.8m trench.
In tests the WY system is said to have proved itself to be an average of 338% more efficient than a boiler/chiller combination achieving an average COP of 5.4, compared to 1.6 for a boiler/chiller. In heating mode the ground source heat pump system does even better delivering a performance that is 515% more efficient than a boiler (COP of 4.89 compared to 0.95).
'However you look at the results the ground source heat pump wins hands down,' explained Philip Ord, Mitsubishi Electric's City Multi product marketing manager. 'WY costs an average of £2.10/m2/yr compared with £13.10 for a chiller/boiler and produces 857.46kg CO2 emissions over the year compared to 2,089.4kg for the chiller/boiler system.'