So I just bought a new thermostat for a rad in my house upon trying to fit the new thermostat the connection nut on the actual rad is too large for this new thermostat. The pipe coming up from the floor is 1/2 in but the connection on thr rad is 3/4". Have looked on screw fix sbd they don't seem to do 3/4 thermostat that fit an older rad. Is there a 3/4 to 1/2 union adapter you can buy as I can't find anything??
3/4 union fitting on old rad, new rad thermostat won't fit
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Do you mean the female thread at the radiators inlet port is 3/4 inch BSP ??
1. If you have not removed the tails from the radiator, sounds as if you have a 15 mm compression fitting valve but a union fitting on the radiator. Union fittings are normally 3/4" BSP.
2. With your new valve you are almost certain to have received a new radiator tail.
3. Remove the old tail from the radiator and fit the new one.
4. You new valve should fit the new tail.
2. With your new valve you are almost certain to have received a new radiator tail.
3. Remove the old tail from the radiator and fit the new one.
4. You new valve should fit the new tail.
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you need a rad key and remove the existing tail and replace with the new one
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You need a rad key
Wot he said too ^^
Wot he said too ^^
It can be, last one I did I had to blowtorch the rad so the fitting would turn, buggers the paint up but I wanted the old tail for a new radiator do it didn't matter
Thanks. Removed the old tail and inserted the new one. Even though I applied some PTFE tap I'm getting a bead of water form on the tail every every 1 minute or so. How tight should you tighten the tail into the rad and is it ok to tighten the tail with the rad back on thr wall and new thermostat fitted?
Better to take the radiator off again. Remove the new tail. Re-wrap with 15 - 20 turns of ordinary PTFE tap (or 5 to 8 wraps of gas PTFE) and screw in again. It should be so tight that the last one or two threads won't go into the radiator.
Very unlikely you can tighten it enough to be waterproof without removing and adding more PTFE.
No harm in tightening with the radiator on the wall.
Very unlikely you can tighten it enough to be waterproof without removing and adding more PTFE.
No harm in tightening with the radiator on the wall.
Leave it for a couple of days and see if self seals
Hmmm I can still see 2-3 rows of thread so maybe I haven't tightened it enough, it was getting tight so didn't want to over tighten and strip the thread (is that even possible on a rad?). Should I undo the nut on the thermostat slightly or is it ok to just tighten the tail without loosening the nut off?
I've stuck an ice cream carton under it to catch any drops and see if it stops after a day or so.
I've stuck an ice cream carton under it to catch any drops and see if it stops after a day or so.
Not usually
No, you'll need to undo/loosen the nut from valve to tail b4 tightening up the tail (I take it that the new tail's got flats for a spanner, not internal hex for an Allen key, unlike the older union tail..)
Yeah the new tail uses a spanner fitting to tighten. Hopefully I can losen off nut and the air lock inside the rad will stop hardly any water coming out and then I can tighten the tail up more.
I guess If I do need to remove the tail completely theres no way getting around having to drain the whole rad down again??
I guess If I do need to remove the tail completely theres no way getting around having to drain the whole rad down again??
Yes, but it's good practice! - to get accustomed to that sort of activity - once you've done it once or twice its no longer a big thing. Hopefully you put plenty of ptfe wraps on the tail. If you do have to remove the tail then it's best to rewrap the threads. Do look on youtube for best way to wrap the tails-some useful stuff there.
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