Works out what flow temperature a radiator needs for its room, and the Heat Emitter Guide star rating that follows.
Most of the form is filled in already with figures that give a sensible answer. Adjust what you know and press the button.
Work out the flow temperature a heat pump must produce to heat a room through a given radiator, and the resulting MCS Heat Emitter Guide star rating, following section 4 of MGD 007.
This is the calculation that decides whether a heat pump will be cheap or expensive to run. A heat pump's efficiency falls as the water temperature rises, by roughly two to three per cent per degree, and the temperature it must produce is set by the radiators, not by the machine.
Supply the room's design heat loss in watts, from a room-by-room calculation, and the rated output of the radiator in that room. British catalogues normally quote at a mean-water-to-air difference of 50 K; if yours quotes 60, say so and the figure is restated.
The result gives the oversize factor, which is the radiator's output at 50 K divided by the room's heat loss, and converts it to a required flow temperature through the BS EN 442 output law. Star ratings run from 0 to 6, one star per five degrees of flow temperature, with six stars at 35 degrees.
Run this for every room. A house runs at the flow temperature its worst room demands, so one undersized radiator sets the running cost for the whole house.
The same calculation answers on
POST /api/calculators/radiator-flow-temperature
and as the MCP tool radiator_flow_temperature.
How to call them.
A heat pump is set up once, on commissioning day, for a house the installer had known for a few hours. The settings that decide the running cost can be improved through the first winter and checked every year after. This covers the settings worth revisiting and the checks worth making each year.
The temperature a heat pump has to produce is set by the radiators it is connected to, and that temperature governs the running cost. This is how the two are related and how MCS measures the relationship.
MCS requires a heat pump to be sized from a room-by-room heat loss calculation. This is what that calculation contains, why the standard insists on it, and how to read one.