How do I remove a radiator to decorate behind it?

Taking a radiator off is a genuinely straightforward job with one hazard that catches everyone: the volume of filthy water still inside it after you think it has drained.

Safety

What you'll need

• Two adjustable spanners, and a radiator bleed key
• Bowls, old towels, a plastic sheet
• A jug and a container large enough for several litres

Step by step

1. Turn the heating off and let it go cold.Completely cold, not warm. This usually means a couple of hours. Hot system water causes serious scalds and it is the only genuine danger in this job.
2. Protect the floor properly.Plastic sheet then old towels, well beyond the radiator. System water is black with iron oxide and permanently stains carpet, timber and grout.
3. Close the thermostatic valve.Turn it fully to zero or off. On some valves it is worth fitting the decorator's cap supplied with it, since a TRV can open itself as it cools.
4. Close the lockshield and count the turns.Pull the cap off the other end and close the valve with a spanner, counting exactly how many turns it takes. That count is how the radiator gets rebalanced afterwards — write it down.
5. Open the bleed valve last, not first.With both valves shut, opening the bleed screw lets air in so the water can flow out. Doing it before closing the valves just drains the system.
6. Crack one union nut slowly.Two spanners — one holding the valve body so you do not twist the pipe. Loosen a quarter turn and let water start to trickle into the bowl rather than opening it fully.
7. Expect several litres.A double panel radiator holds a surprising amount. Have a second container ready and be prepared to tighten the nut again to swap bowls mid-flow.
8. Tip it carefully once drained.Undo the second nut, lift the radiator off its brackets with someone helping, and tilt it towards a bowl as you go. There is always more inside.
9. Plug the ends before moving it.Plastic bungs, or tape over the openings. Carrying a radiator through a house without plugging it is how hallways get stained.
10. Take it out flat and rest it on protection.Outside if possible. It will keep seeping for hours, so do not stand it on a finished floor.
11. Decorate, then refit in reverse.Radiator back on the brackets, both union nuts hand tight then nipped up with a spanner. Do not overtighten — the seal is on a taper, not on force.
12. Reopen the valves in the right order.Bleed screw closed, then open the lockshield by exactly the number of turns you counted, then open the TRV. That preserves the system balance.
13. Bleed it and check the pressure.Bleed the radiator once the heating has run for a while. On a sealed system, check the pressure gauge and top up to 1.0 to 1.5 bar if it has dropped.
14. Check the joints the next day.Kitchen roll wrapped round each union overnight. A slow weep does not show immediately and is far easier to catch early.

Tips

• Count the lockshield turns and write the number down. It is how the system stays balanced and it takes two seconds.
• There is always more water than you think. Have a second container within reach before you start.
• Plug the ends before carrying it. Radiator water stains carpet permanently.

Common mistakes

• Opening the bleed valve before closing both valves — It drains the system rather than the radiator, and you end up refilling and rebleeding the whole house.
• Undoing a union nut with one spanner — It twists the pipework and can crack a joint elsewhere. Hold the valve body with a second spanner.

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