Rad not getting warm/hot

[jjfresh66]

Hi,

Recently our work had the builders in and they did a bit of plumbing.
Anyway one of the downstairs Rads doesn't get hot, it's totaly cold and i've checked the TRV pin and it seems AOK. It's fed by a combi system. Pressure 2 bar + operating - I've bled the rad and at first there was some air in it but now the water is stricking out it still doesn't get hot. It is only trickling so i'm not sure if that is right.

I've followed the return and feed pipe back about 3 metres and these are both hot. If i touch the pipe directly under the Rad valve it's (freezing).

I also checked the return valve and i'm sure that's on (fully) anticlockwize)

Do i require to go round the upstairs rads and bleed those two ?
Any help on this thanks.

 

[jjfresh66]

I've noticed that the TRV is on the left as apposed to the right on all the other Rads. Could this be the problem, they have conencted the pipework backup wrong or does it not matter which side the TRV's are placed.

Thanks

 

[JohnD]

modern TRVs it doesn't matter. older ones may be a bit noisy if on the return, but still work. TRVs sometimes stick, and the pin won't come up to open position.

check lockshield is fully open (count the turns as you may need to put it back later) and close the other rads to see if this one warms up

if the water is only trickling out you may have insufficient water, or a blockage, which might be sediment. How old is the heating system?

bleed the other rads, the water should squirt out forcefully, even on the top floor.

 

[D_Hailsham]

modern TRVs it doesn't matter. older ones may be a bit noisy if on the return, but still work. TRVs sometimes stick, and the pin won't come up to open position.

Check if the TRV has one arrow on the body (single direction flow) or two arrows at right angles (bidirectional flow).

check lockshield is fully open (count the turns as you may need to put it back later) and close the other rads to see if this one warms up

That just proves the system is not balanced properly.

 

[JohnD]

just?

 

[shambolic]

The pin may be out but the valve could still be stuck to the seating on the trv.
Try a hammer on the side of the valve and chap it a few times this may left the seating. Or shut both valves and remove rad from pipework. Then open one valve at a time into a bucket and see what type of pressure from each(should be similar) if one is a lot less then this pipe or valve is blocked!

 

[jjfresh66]

Well thanks for the help guys. I will double check the lock shield valve and pin on the TRV. If that doesn't work i will remove the rad and test the pressure at both ends. I have a funny feeling that it will be blocked.

Last time i removed a rad with a TRV on water was still pumping out, even thought it was turned fully off. Is there a nak to this ?

cheers

 

[D_Hailsham]

just?

OK

I should have said: that just proves either the radiator is blocked or the system is not balanced properly.

 

[jjfresh66]

Ok the problem was with the Lockshield valve - I uses an ajustable spanner to turn this fully left, it was really tight and i thought it was going to break (must not have turned this hard enough yesterday).

Anyway it moved about a quarter of a turn - fully left. Immediately the pipe became hot directly underneath the LSV - before it was only hot 3 mtrs back from the LSV. Took about 5 mins and all the RAD is now fully HOT.

Great work and it's really good that people are around to help and not just let people struggle.

Good day !!

 

[D_Hailsham]

Last time i removed a rad with a TRV on water was still pumping out, even thought it was turned fully off. Is there a knack to this ?

Some TRVs only close down to a frost setting, so they are still slightly open.

You have two options: Get hold of a "decorators cap" for the TRV from the Mfr or a plumbers merchant (not a DIY shed); or, set TRV to max, remove the head from the TRV, insert a small coin in the head, then replace the head. Slowly close the TRV until it stops (usually around 2 or 3). Don't force the TRV down to the lowest setting - it won't get there. The coin takes up the slack between the pin and the moving part of the head so the valve then shuts completely.

 

[jjfresh66]

Thanks for the advice on shutting the TRV down D_Hailsham