Heating Help please! - One Radiator is warm on top but cold at the bottom?

Virdi · 30 Nov 2016 at 08:28

Hi all,

We have one Raditor in our kicthen ...which seems to be warm on top - but cold on the bottom half?

Feeling the pipes ...one pipe is warm and the other is cold?

Does this sound like a dodgy TRV?

Thanks

robj20 · 30 Nov 2016 at 08:39

Sounds like slow flow. It could be the TRV not opening fully, take the head off and see if the pin moves freely.

Virdi · 30 Nov 2016 at 08:52

Thanks

Yep - Just done that and the Pin in the middle seems ok.

I pushed it down a few times and it pops back up no problems.

However, even before I done that I noticed that the bottom of the Rad was warm now and not cold anymore ...but still not HOT HOT.

robj20 · 30 Nov 2016 at 11:05

If it slowly gets up to temp is definitely slow flow, open up the lockshield a tiny amount, we're talking about 1/8th of a turn.
You won't really know if this works until it's all gone cold and put back on again.

iraiguana · 30 Nov 2016 at 11:07

Depending on age and how often it was treated, could be a sign of sludge build up in the radiator.

When was the last time inhibitor was added to the system? Potential fix would a be a powerflush and re-fill. I caution this as old systems may spring leaks if the seals fail under the pressure used during a 'power flush'.

Virdi · 30 Nov 2016 at 15:03

robj20 said:
If it slowly gets up to temp is definitely slow flow, open up the lockshield a tiny amount, we're talking about 1/8th of a turn.
You won't really know if this works until it's all gone cold and put back on again.

Thanks

To open ...I turn it anti Clock wise?

Virdi · 30 Nov 2016 at 15:05

iraiguana said:
Depending on age and how often it was treated, could be a sign of sludge build up in the radiator.

When was the last time inhibitor was added to the system? Potential fix would a be a powerflush and re-fill. I caution this as old systems may spring leaks if the seals fail under the pressure used during a 'power flush'.

Hi, This rad is one of the newest in the whole house ...it's about 5 years old.

I has inhibitor added less than a month ago ...and the Magna Clean was totally clean when the heating engineer cleaned it out.?

GeForce · 30 Nov 2016 at 15:06

Virdi said:
To open ...I turn it Clock wise?

Anti-clockwise

robj20 · 30 Nov 2016 at 15:25

Just as a test next time the system comes on from cold, go round the house and see if they all come to temperature about the same time. Any that are noticeably cooler than the others need the lock sheild opening a little. Buts its a balancing act between opening the slow ones and closing any fast ones.

dirtychinchilla · 30 Nov 2016 at 15:26

Radiators build up crud in a sort of bell pattern, so if this radiator is old and hasn't been drained ever, this may be your problem. It's very typical that radiators are hot at the top and cold at the bottom.

Having said that, just seen the post above!

robj20 · 30 Nov 2016 at 15:31

dirtychinchilla said:
Radiators build up crud in a sort of bell pattern, so if this radiator is old and hasn't been drained ever, this may be your problem. It's very typical that radiators are hot at the top and cold at the bottom.

Having said that, just seen the post above!

Try reading the thread, lol.

Virdi · 1 Dec 2016 at 07:25

Update:

So I tried playing with the Lock Shield and it hasn't made any difference.

The thing that I can clearly see / feel is that:

The copper pipe coming into the rad (which has the lock shield on it) is HOT. However, the copper pipe that has the TRV connected is cold (but does get slightly warm over after a few hours)

I checked the TRV and the pin is moving up and down and I gave the TRV a little knock etc...

So I am thinking it might have sludge built up inside the radiator?

robj20 · 1 Dec 2016 at 07:34

How old is the TRV, only newer ones are able to work properly on the return side.
Check to see if there are any arrows on the TRV valve body, two arrows means its fine, one arrow means its been piped up wrong way round.

If you think its sludge, shut both valves off and take the rad off use a hose pipe to flush it out, however if like you say its a new rad i wouldnt expect it to be this, otherwise the whole system would have sludge.

BigBoy · 1 Dec 2016 at 08:48

I agree with the above, it sound slide the trv and lockshield need to be swapped over, there is always the possibility of sludge build up, it could even jusy be a flake stuck in the trv.