Switch between heating (radiator) and air-conditioning modes. Enter room dimensions, insulation, windows and orientation — we give required watts, BTU/hr and the nearest standard split A/C size.
Guideline for EU 230 V wet central heating. For heat pumps, oversize by ~20 %.
Rule of thumb: room m³ × 40 W (150 BTU/h) for a well-insulated room, × 50 W (170 BTU/h) for older properties, × 60 W (200 BTU/h) for conservatories or rooms with a big north-facing window.
A 20 m² × 2.4 m room = 48 m³ × 50 W ≈ 2400 W (~8200 BTU/h). A 600 × 1200 mm double-panel Type 22 delivers roughly that at ΔT50 — check the manufacturer's ΔT50 rating.
It's the temperature difference between water and room used to rate output. Modern condensing boilers run cooler (ΔT30), which cuts output by ~50 %. Size on ΔT50 then confirm the actual system ΔT.
Yes. Add 10 % for tiled floors, 10 % for single glazing, 15 % for a room above a garage or over an unheated space. Subtract 5 % for very well insulated new-builds.
Bathrooms are sized 10–15 % higher than living space because you want them warmer. A 6 m² bathroom at 2.4 m high is 14.4 m³ × 55 W ≈ 800 W (~2700 BTU/h) — most standard chrome towel rails only give 300–500 W, so pair one with a small panel radiator.
Slightly oversize. An oversized radiator reaches temperature sooner and then throttles back on its TRV, which suits condensing boilers running at lower flow temperatures. An undersized one runs flat out and never quite heats the room on the coldest days.
Estimates only. Check the paint tin / adhesive bag for the exact coverage of your product.