Why heat pumps are designed around low flow temperatures, heat loss and bigger emitters.
A heat pump moves heat rather than burning fuel, and it works most efficiently at low flow temperatures. That single fact drives the whole design.
Heat loss first. The system is sized to the property’s calculated heat loss, not to an old boiler’s output. A well-insulated home needs less, so fabric improvements pay back twice.
Low flow temperatures, bigger emitters. Because the water is cooler than a boiler’s, each radiator gives out less heat — so emitters are upsized, or underfloor heating is used, to deliver the required output.
Hot water is provided through a cylinder with a large heat-exchanger coil, reheated more gently than by a boiler.
Controls such as weather compensation keep the flow temperature as low as conditions allow, protecting efficiency (the seasonal performance, often quoted as SCOP). Exact figures come from the heat-loss calculation and the manufacturer/MCS design.
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