How to fix a broken towel radiator

In a first for this blog – as a lame attempt to counter the increasing amount of dross when you google simple household tasks, and for my own reference – here’s a post with some DIY instructions. How I fixed our leaking towel radiator which conveniently decided to break and stop the heating working on 23rd December.

Tools and consumables

Purchase list:

• Replacement valves
• Pipe wrench
• Radiator spanner
• Plumb tub

Optional:

• Olive puller
• Pliers
• Inhibitor

Also needed:

• Adjustable spanner
• PTFE tape
• Junior hacksaw

Check the valve is the right size and orientation for you. Our pipes come out of the wall perpendicular to the wall, the the radiator is at a right angle with downward facing holes. Pipe is usually 15mm, radiator is usually 22mm.

Method

1. Drain the radiator. Turn off the central heating (I turned off the boiler power). Attach the plumb tub to the pipe. Using a wrench to hold the valve steady, start to unscrew the nut on the radiator end. It will start draining water from the radiator when loose. Collect the water in the tub. Once the flow slows, open the valve at the top with a radiator key to release the vacuum and get the rest of the water out.
2. Remove pressure from the system. Now drain the rest of the central heating system by loosening the nut attaching to the pipe from the wall. It may be easier to reconnect the other nut first to keep the radiator valve steady with the wrench. Our radiator is upstairs so this was quick. Alternatively you could connect a hose to a release valve (usually downstairs/first radiator on). You should see your boiler show zero pressure.
3. Remove valve and pipe olive. Completely remove the nuts from each end of the valve. One of the trickiest bits here is the pipe olive, the little metal ring round the pipe at the joint, which may be stuck to the pipe if the joint was overtightened. Best practise is to attach a new pipe, but this is a lot of work. You can use the olive puller linked above for the safest solution. Unfortunately mine had a non-standard sized nut for some reason, so this wouldn’t work. I instead sawed diagonally across using the hacksaw, and my thumb as a guide. Be very careful when close to getting through as you don’t want to nick the pipe. When it’s almost through, put in a flat-head screwdriver and pop the ring off. Very satisfying when it works, but be careful with your fingers. Don’t forget to remove the old nut from the pipe when you’ve got the olive off.
4. Remove radiator tail. Using the radiator spanner, unscrew the inside of the valve piece that goes inside the radiator. If you look at/try on the replacement valve it will be obvious how it works.
5. Add new radiator tail. Do the opposite to add the new valve back on. You’ll need to wind PTFE tape around each threaded side of the valve here, go clockwise a few times and avoid the final thread. Then use the radiator spanner to put the tail in.
6. Attach tail to valve. Use PTFE tape around the thread on the valve, attach into the new tail. Tighten with wrench and spanner, only needs 1-1.5 turns beyond finger tight.
7. Attach valve to pipe. The joint here doesn’t need PTFE tape as it’s a compression joint. Add the nut, then the new olive onto the 15mm pipe from the wall. Use your wrench and spanner to tighten the joint, avoiding overtightening.
8. Refill the system. I would first close both valves on the radiator as you refill. Note at this point you may want to add inhibitor to the radiator from the top nut on the other side to the bleed valve. Use the water loop on the boiler to add pressure to the system until at about two bar, then close again. Check your new valve isn’t leaking. If it is, you may need to tighten, redo your PTFE tape, or add PTFE tape around the olive.
9. Refill the radiator. Close the bleed valve, open both of the valves by 1/4 of a turn. Once it’s full you can open the bleed valve to completely fill the system, until water comes out of the top. Note you’ll probably need to add more pressure by opening your water loop again during this process. I aimed for around 1.2-1.4 bar when the system is full.
10. Bleed and balance the system. Depending on where the radiator is, you may need to bleed the rest in the house, and add more pressure to the system. Once you’ve done that turn the heating on to test the radiator heat. I had the lockshield valve at 1/4 open, and the other valve fully open. The valves are identical on these radiators so there isn’t really a lockshield, but having one fully open, and the other slightly open to adjust to the correct heat seems standard.

Notes:

• Removing the pipe olive is the only tricky bit.
• You really don’t need to overtighten the joints to make it water-tight.
• If you can’t find identical or very similar replacement valves this would be more difficult as the 15mm pipe might need redoing, but there probably is some clearance/give.
• Feels a bit nerve-wracking with water if you’ve not done much plumbing before, but it’s a closed system so you’re not going to get a leak. Worst case is your heating/hot water might be broken if you can’t sort the valve. I would have put the old once back with more PTFE tape if this had happened.

References

• Using PTFE tape
• Same situation, but repair o-ring not full valve replacement
• Removing a stuck olive

Collins Complete DIY Manual (I have a 1980s edition which was £3 from a charity shop) was very useful, but as usual quite brief.