/ Plumbing/Radiator Problem

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Hugh J - on 11 Nov 2012
Calling all plumber/heating engineers.

I have a radiator that is not heating up .I've tried bleeding it, luke warm water is coming out, but still no go. The pipe at the thermostat end is cold, but the pipe at the other end is hot. This has happened since I removed another radiator in a different part of the house to plaster a wall. That one has since been replaced and works fine.

Any suggestions?

Thanks.
John_Hat - on 11 Nov 2012
In reply to Hugh J:

That sounds like its the wrong way round.... Thermostat is normally at the "feed" end on the radiator. Mind you modern thermostats can work either way.

Possibly some crud has got dislodged and is jamming the valve at the inlet. Or the valve is just kaput.
Hugh J - on 11 Nov 2012
In reply to John_Hat: Thanks John, was thinking about taking it off to have a look. Just thought someone might know of a quick fix.
John_Hat - on 11 Nov 2012
In reply to Hugh J:

Note I'm not a plumber, and I'm sure someone with more experience will be along shortly to possibly give you the quick fix you are looking for.. :-)
gethin_allen on 11 Nov 2012
In reply to Hugh J:
Could it just be a balancing issue? If you turn off the new rad you recently replaced does the problem rad get hot?
If so just close off the lock shield valve (the one on the other end of the rad from the thermo valve) on the new rad just enough to get the problem one hot.
Hugh J - on 12 Nov 2012
In reply to gethin_allen: Cheers Gethin, I'll give it a go, but when I said "replaced" I didn't actually mean a new one - it's the same rad.

However, a couple of years ago I added a couple of towel rails coming off the feed to the problem rad - it worked fine. I'm wondering if by changing the loop I've somehow created a point in the pipe work that could cause and air-lock, which only occurred when I drained the system from the rad I removed. Both towel rails are hot. Maybe as you say, it's an imbalance problem, but maybe it's the the towel rails I need to look at?. What do you think?
Jim C - on 12 Nov 2012
In reply to gethin_allen:
> (In reply to Hugh J)
> Could it just be a balancing issue? If you turn off the new rad you recently replaced does the problem rad get hot?
> If so just close off the lock shield valve (the one on the other end of the rad from the thermo valve) on the new rad just enough to get the problem one hot.

I agree with that, I tweaked all the hottest radiators upstream of the cold one that I had ,shutting the loch Shield valve a touch restricting the flow, and reducing the temperture of the over hot ones. The water started to flow through the cold one, but do it gradually and leave it for a while to settle, don't make big changes and expect immediate results.

nedmoran on 12 Nov 2012
In reply to Hugh J: You could also unscrew the top of the trv(valve) head. There will be a small pin head or nipple. Use something to press this down a couple of times to make sure it hasn't jammed.
EddInaBox on 12 Nov 2012
In reply to nedmoran:
> You could also unscrew the top of the trv(valve) head. There will be a small pin head or nipple. Use something to press this down a couple of times to make sure it hasn't jammed.

Top tip from me... don't try pulling it up with a pair of pliers to unjam it!
gear boy - on 12 Nov 2012
In reply to Hugh J: air lock? shut off the hot radiators totaly and fully open the cold one, see if it will push through, had this on a downstairs radiator and had to turn of all the other rads in the house so just the one rad on, and all of a sudden big gurgle sploosh and hey presto it works now!
Hugh J - on 12 Nov 2012
In reply to nedmoran: Cheers Ned (and others for the advice).
TRV it is then, the pin was stuck in (closed), but now freed up. When I leave it in the open position the rad heats up. I can manually push the pin in and pulled it out - quite easily, but it doesn't return to the open position on it's own accord. Is this normal or because it's had it or because the system pressure is too low -about 1.5 bar?

Cheers in advance.
mrchewy - on 12 Nov 2012
In reply to Hugh J: They just get stuck sometimes after a few years if they are not used regularly - I spent an hour freeing up a customers last year and still had to replace a couple of them. Pressure sounds fine.
nedmoran on 12 Nov 2012
In reply to Hugh J:No probs ;)
Hugh J - on 12 Nov 2012
In reply to nedmoran: Thanks Ned & Mr Chewy, problem solved with a bit of working the pin and some olive oil - now working fine. Yippee!
Baron Weasel - on 13 Nov 2012
In reply to Hugh J: You probably don't want the pressure higher than 1.5 bar unless you have a very tall building with the boiler in the basement.

Rads need 0.1 bar per m higher than the boiler roughly so 1.5bar should work up to 15m above the boiler.

BW
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Frank4short - on 13 Nov 2012
In reply to Hugh J:
> (In reply to nedmoran) Thanks Ned & Mr Chewy, problem solved with a bit of working the pin and some olive oil - now working fine. Yippee!

Olive oil will degrade and attract dirt with time. Leaving you back where you started. Probably best to clean it off and get a more durable lubricant to replace it with.

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