The plant a European house runs on: an outdoor coil taking heat from 7 °C air, a scroll compressor, a coaxial condenser heating a water loop, a circulator, and radiators giving it to the room. The radiators are a **hydronic emitter** — rated the way EN 442 rates one, an output at 75/65/20 °C and a characteristic exponent, with no geometry, because that is what a radiator maker publishes. They are deliberately oversized, which is what a heat-pump installer does: 34 kW at the EN 442 rating, more than twice the 14.7 kW the machine puts into them, so it settles at 52 °C flow (42 °C return) and a COP of 3.37 at the compressor instead of the 59 °C and 2.78 that boiler-sized radiators of 24 kW would have forced. A sixth of the running cost, bought with nothing but bigger radiators. Published as an example; the figures below are solved from this model.

Example12–18 kW heatingEU

Example system. Published by HVAC Builder to show suppliers what their own page looks like. There is no company behind it and it is not a product offer — the specification is generic and the performance is solved from the model on this page.