Heat Pump Overview; Co-Efficient Of Performance; Varying Factors - Mitsubishi Electric Ecodan PUHZ-W50VHA-BS Homeowner's Manual

Heat Pump Boiler Overview
A heat pump works in a similar way to that of a domestic fridge, although in re-
verse. Heat is moved from one source to another. The outdoor based Ecodan
exploits the physical properties of a refrigerant to heat water that flows into the
dwelling to the radiators/ under-floor heating and the hot water cylinder for hot
water usage. This is a very efficient way to heat water compared to conventional
gas, oil and solid fuel boilers.

Co-efficient of Performance

Sometimes referred to as COP, it is the amount of heat energy provided by the
heat pump, divided by the electrical energy consumed by the heat pump.
The efficiency of a heat pump boiler is high compared to a gas boiler. Typically for
every 1kW of input energy, 3kW of outputted heat energy can be achieved, that
creates a COP of 3.0. If heat energy increases for the same input the COP would
rise.
Compared to a gas fired conventional boiler, 1kW of input energy provides less
than 1kW of output energy or heat. A heat pump boiler utilises heat energy from
the outside air even at low temperatures to provide either central heating or hot
water for the house.
The COP for an ASHP will vary as it is dependent on the outside temperatures
and the desired temperature of hot water/ space heating. The smaller the differ-
ence between these figures the more efficient the Ecodan® will become. When it
is cold outside power input increases as the Ecodan® works harder to extract
heat from the air, thus COP drops in cold conditions.

Varying Factors

The table below shows how performance will vary. The Inlet/ Outlet temperature
COP at varying factors
°C ambient Water temp °C
Inlet / Outlet
30 / 35 40 / 45
-15 1.77 1.41
-7 2.41 1.89
2 2.97 2.27
7 3.96 3.05
20 5.39 3.90
represents the water temperature
progressing through the Ecodan®
unit and heating up.
50 / 55
Figures for 8.5kW heat pump
1.37*
* Ambient Temperature –10°C
1.46
1.81
2.28
2.87
3