I have one rad out of five not working, the TRV valve is working physically, the valve pin underneath is moving up and down freely and there is water in the rad but no heat is moving through it – any ideas?

vavle on the other side if fitted blocked /broken? Does heat reach the pipework but not the radiator?
Air block in the system meaning heat wont transfer?
Valve turned off elsewhere in the system that feeds that radiator?

Pipework not getting hot either, it worked last winter but not now for some reason, haven’t turned off a valve that i’m aware of…

Try bleeding the radiator probably an air lock

Tried bleeding it, how much water should come out before it’s done?

Turn all the other radiators off & then bleed it..My mom’s system has one radiator like this & once it’s forced through it works fine for the rest of the winter….

If there is water coming out the airlock must be in the pipe work so you would need to continue beading until it gets hot

turn all the other rads off turn the temp on boiler to max and.. away you go its like magic..

Right, i’m stumped.

I’ve bled at least ten litres of water out of the radiator, the pipe and valve are getting red hot but the water coming out of the bloody bleed valve is staying cold!
What’s happening and can i do something without calling out the plumber? 👿

have you checked the valves at both ends?

It was working last winter, i haven’t touched it til this winter so i haven’t turned any valves off.

I’ve taken that much water out of the system i’ve had to top up the boiler pressure twice now and i still can’t get any heat into that rad.

have you bled ALL the radiators… usualy an air lock….. i go round checking mine periodically..

i have a problem when i run the bath water… every 20 seconds or so the ruddy water goes cold for a minuit then runs hot agin…its like that all the time …lol

do what totalshell suggests, if no joy you may have a blockage.

I am no pro, but from what you have written I would suspect an air lock still either in the feed or the return. I would try turning off the thermostatic valve and then bleeding so that flow is fed through the return valve, then if that does not work, turn off the return valve and open the thermostatic valve and bleed again….loads.

Have you checked that the thermostatic nobby thing is ok by swapping it with one from another radiator?

It might be a mystery, but come on… its great fun diagnosing it 🙂

You might not have touched the other valve, but a visitor could have. Check its open, turn it all the way open, once the rad gets hot, or you’ve proved the valve isn’t the problem, set it back to what it was. (count the turns, if you guess it could cause further problems by unbalancing the system)

In the past I have had a similar problem the TRV valve looks as if it’s working properly, but the innards had stuck. I tapped the valve with a hammer whilst turning the valve on and off, eventually the radiator got hot.

Elaine, your boiler could be cutting out due to low water pressure, check it for intermittent fault lights whilst the bath taps are in full flow. Could be as simple to fix as not turning the taps on so fast 🙂

I’ve taken the TRV off the pipe work completely, and the pipe work is getting hot but not the rad. The bathroom rad (problem rad is in a bedroom) does get an airlock periodically but i bleed that regularly. All other rads are toasty hot but not the 2nd bedroom one.

If the valve is nearly closed because of balancing then I’ve often had debris get under the valve and block the lockshield. Try it it is so simple to prove and I’ve had it too many times.

balancing??

Muddydwarf, just to clarify, the ‘other’ valve is the lockshield valve, the one that has a smooth cap and needs a pair of pliers or similar to turn.

As I said earlier, just count the turns to fully open, then when the rad is fixed, count the turns back. If its close to the boiler it will normally be nearly fully closed, if you are far from the boiler it will be near fully open.

Just been up to check, the rad in question doesn’t have a 2nd valve as such, just a plastic end cap over a flat part that looks like a rather blunt screwdriver so not something that can be turned on or off without pliers etc.

Really puzzling me now, had loads of bowlfuls of water come out of the rad, the pipe and valve get hot but water coming out of the rad remains cold. Then, when i check the boiler levels it’s dropped into the red zone so i refill it and start again…

Ah, lockshield… Hang on…

balancing means regulating the flow of water to the radiators to ensure efficient operation of the heating system. This is done with the lockshied or balancing valve as opposed to the TRV or control valve. It should have a head which can’t turn the actual valve spindle therefore not upsetting the balancing of the system with regular use.

what colour is the water from the bleed hole?

try ‘helping’ the valve underneath with some pliers. ‘help’ it up and down a few times with the heating on. Sounds like you’ve got a blockage of some sort. My guess is gunk around the valve pipework.

winding out the lockshield might just shift whatever is blocking yer pipes.

Water from the bleed hole is a little brown for sure, i only had the system flushed 2 yrs ago when i had the boiler fitted.

Heating is off for the night now anyway.

If the bled water is cold but the valve is glowing then it would suggest it’s the reserve water that you’re taking out. I still reckon the problem is at the valve end but anything that blows it through is worth a punt.

reserve water? (i have zero knowledge of plumbing!)

I don’t have zero knowledge – but reserve water is a new one on me?

probably not the best description, the water you’re bleeding might be flowing from the lockshield end. It’s pressurised and the only escape is your bleed hole so it effectively flows backwards round your system. It would explain why your valve is magma, your rad isn’t and you have to keep topping up.

to get the valve hot you only need a small flow rate, but to heat the rad you need a greater flow rate. Think of a loop of pipe with a restrcition in the circuit somewhere. The valve will get hot no matter where you put that restriction as it still allows the minimum flow needed to heat the valve but not the read.

Not reading all that, and Bear has probably sorted it for you.

But

Turn all the rest off and put the heating on. If it heats, then it proves it can. Give it 10 minutes and turn the rest on and see if it gets hot. If theres air in one of the legs then hopefully this will clear it.

Come back after you have done this.

Edit. Sorry for sounding arsey. STW is practically unusable on iPhone for me these days.

In the past I have had a similar problem the TRV valve looks as if it’s working properly, but the innards had stuck. I tapped the valve with a hammer whilst turning the valve on and off, eventually the radiator got hot.

this.

nearly all of the valves in my office get like this so I have to take the valves off and lightly tap the pin with a hammer to free it. The pin itself isn”t directly connected to the valve underneath, it just pushes down on it so it is possible for it to be free but the valve underneath still stuck.

WOOHOO!!!!!

Success is mine! We now have a rad kicking out near nuclear levels of heat and the cats are in heaven 🙂 I undid the lockshield valve a few turns before i went to bed last night and it’s toasty this morning.
I’ll let it run through this morning and i’ll reset it tonight.

Thanks all.

Congratulations ‘muddydwarf’!
I followed this with interest as I had thr same problem – I tried all the tricks suggested here by mine is still not working 🙁

The feed pipe to the rad does not get hot at all (even with boiler on max and all other rads off).

Cold rad is closest to the combi boiler (small flat, only 5 rads in total).
I know this thread’s been done to death but if anyone has any further thoughts we’d all be MASSIVELY grateful…

Barn, i bled the rad several times, taking out a good 10+Litres of water and topping up the boiler pressure each time.
Maybe do that as well as opening the lockshield?