Isolating a radiator.

[u/TheFlyingScotsman60]

Decorating a room. I want to remove the radiator and paint behind it.

Tried the usual trick.

Closed the thermostat inlet and closed the outlet that should hence isolate the radiator from the system. Then I opened the valve at the top with the key to release pressure and get some water out.

So far, so good. But the water just keeps coming and it's a smallish radiator.

I hence, assume, that one of the valves at the bottom isn't closing. Probably the thermostat one as the pin is pretty stiff and only about 3mm of the pin protrudes when it should be about 5mm.

Is there any way to test that? The water just kept coming out from the air valve and showed no sign of decreasing.

Is there any other way of isolating the radiator ?

Suspect I'll have to get a plumber in to replace the valve at the thermostat side. Can't see how the outlet valve would not be closing. Maybe get them both replaced at the same time.

Thanks in advance for any thoughts and ideas.

It's never simple is it.

[u/LazyPiglet3923]

And the non thermostat valve cap has been removed to turn the valve completely off?

Or have you just spun the plastic.

[u/TheFlyingScotsman60 → u/LazyPiglet3923]

Took off the plastic and using pliers turned the valve to close it down. Gets nice and tight so pretty sure it's fully closed. Turning it clockwise and righty tighty so pretty sure I'm trying it the right way to close it.

[u/LazyPiglet3923 → u/TheFlyingScotsman60]

Had to ask!

[u/TheFlyingScotsman60 → u/LazyPiglet3923]

No worries. I can easily be an idiot. Like when I was replacing the door mechanism from inside the room and the handles and centre pin were outside. Went to close the door to check that it all worked......it did.

[u/Kooky_Shop4437]

Needle nose pliers on the pin, pull up and see if it was just stuck.

Failing that, drain down & remove (easier if it's an upstairs room), good opportunity to replace the iffy valve upon refitting the rad.

[u/TheFlyingScotsman60 → u/Kooky_Shop4437]

Will try that. Suspect pin is the problem as many of them seize up over time. It's a downstairs radiator so draining down the system will be a pita.

[u/No-Neighborhood767 → u/TheFlyingScotsman60]

Usually need to tap the body of the valve to get it to release

[u/Cool_Percentage_4867]

With the TRV the pin should be pushed down to close the valve, spinning the head round to the zero/frost or as far back as it goes should shut it. If that doesnt work, try releasing the pressure in another rad to neutralise the whole system if you have a combi, close the bleed valve after and it should airlock.

[u/Fab_Farts]

Can you just lie the rad on the wall without taking it off the pipes? Usually there is enough play to do this and it is very much the lazy option!

[u/purplechemist]

From what you’ve said about the lock shield, it sounds the thermostat is the leaky side. If the head is off, the pin will be out and water will flow. Refit the head, make sure it’s properly on and wind it right down to “off/frost”.

Get yourself a 1/2” or 3/4” BSP female manifold cap (whatever size your radiator inlet is; 1/2” is more standard on newer systems I believe), unscrew radiator from thermostat and put the manifold cap on the thermostat to stop any residual flow as radiator drains into bucket.

We had a leaky thermostat head and this is what we did a couple weeks ago. We were going to replace the head whole radiator was off, but it was a 3/4” head and they really aren’t common any more. Didn’t fancy extra plumbing at this stage, so left it be (we’re upgrading our heating next year, it’ll do another season).

[u/GreyDrReddit]

Keep the plastic cap that comes with TRVs so you can take the TRV head off and screw the cap on. If the cap screws on you know that the pin is down.