How to Replace a Radiator

Before You Start

Turn off the central heating and let it cool completely. Gather your tools: adjustable spanners, a radiator bleed key, a bucket and towels, PTFE tape, and the new radiator. Check the new radiator's BTU output matches or exceeds the old one for the room size.

Step 1 — Drain the Radiator

Close both the lockshield valve (use a flat-head screwdriver) and the thermostatic valve (TRV) at each end of the radiator. Place a bucket and towels under one valve. Open the bleed valve at the top of the radiator and loosen the union nut on one valve — water will drain out.

Step 2 — Remove the Old Radiator

Once drained, loosen both union nuts at each valve end. Lift the radiator off its wall brackets. Most radiators are heavy — get someone to help. Cap off or plug the open valve ends while you work to prevent debris entering.

Step 3 — Fit the New Radiator

Wrap new blanking plugs and valve tails with PTFE tape. Fit these into the new radiator. Hang the new radiator on the existing wall brackets (if compatible) or fit new brackets. Reconnect the valve union nuts, tightening firmly with a spanner.

Step 4 — Refill and Test

Open both valves. Bleed the radiator using the bleed key until water flows steadily (no air). Check all connections for leaks. Check boiler pressure and top up if needed. Turn on the heating and check the radiator heats evenly.

Choosing a Replacement Radiator

Ensure the new radiator has the same or greater BTU (heat output) than the original. Standard double panel radiators (type 22) offer the best heat output for their size. Designer radiators look great but often have lower BTU outputs.