Cold Radiators

morpheus83uk · 11 Dec 2017

Hello,

We have recently had new radiators put in with the exception of two (about 4 months ago now) and we have had a new boiler around 2 years ago. However the problem with the radiator in the living room remains the same. It is warm at the top and cool at the bottom like it has a little bit of warmth but not much.

I have read people saying its sludge but the system has been drained several times and the affected radiator blasted out with a hose pipe until it run clear prior to the new radiator being put in. Also when the new radiators were put in the guy who did them vacuumed out each hose of the radiator.

Does anyone know what this could be?

Thanks

James

JohnD · 11 Dec 2017

turn off ALL the hot ones. Does the cool one now get hot?

morpheus83uk · 13 Dec 2017

Thanks for the response I will give it a go at weekend.

What would be next to try if it does / doesn't get hot?

Also when you say turn them off do you mean just turn the numbered valve to 0?

Thanks

James

wig · 14 Dec 2017

To give this post some context.......I am an amateur, DIY, I just fixed my boiler.....I'm still learning...aren't we all?

Your numbered valve is a 'TRV' on the opposite side of the radiator is another valve called a 'lockshield'. Shut all other radiators in the house off using the lockshield valve clockwise to close anti clockwise to open. You only need to close the locksheild for the rad to be off, no need to touch the TRV.

The upstairs radiators should only require 1/4 to 1/2 a turn to close the lockshield if the upstairs ones are fully open and require lots of turning to close this could be part of your problem. Apparently when setting up your system you should fully close the lockshield on the upstairs rads and then open it by 1/4 to 1/2 a turn on each one. Look on youtube for videos "how to balance your radiators". Now I understand the theory of why to do this. but what I don't understand is that surely there are radiators upstairs that are as far away from the boiler as some of the ones downstairs and vice versa with some upstairs close to the boiler and some downstairs close to the boiler...so I don't see that this rule of thumb is correct. But anyway....

What happened when you turned them all off except the one in the lounge with the lounge one both valves lockshield and TRV fully open ?

terryplumb · 14 Dec 2017

Wig ,your advice given above is somewhat flawed. The op only needs to close the trv valves on his hot rads ,to see if this brings the cool ones on.the lockshield valves ,used to balance the system , don't need to be closed. If they are closed for any reason ,each rads LS needs to be opened back to its original position to maintain the balance. So before closing ,one should make a note of how many 1/4 turns it takes to close ,which most likely will not be the same on every rad.regards terry.

JohnD · 14 Dec 2017

morpheus83uk said:
do you mean just turn the numbered valve to 0?

yes.

I estimate it will take you about three minutes to do all of them.

So you can do it today if you want, while your tea brews.

wig · 14 Dec 2017

Yes I agree, if the LS valves are all set correctly then you don't want to be closing them and losing the settings. But if like in my house the LS are all over the place, it would not matter. I do think the OP should use a marker pen or a bit blu-tac on all his LS valves then turn them all shut counting how many turns it takes and then re-open to the exact position, and leave a note on each rad which says how many turns it took for each one. Then at least he would know where all his rads are set

I just didn't want the OP turning the TRV to frost which is still open and thinking he had closed it.

morpheus83uk · 16 Dec 2017

Thanks for the replies. I have tried turning off all the TRVs to 0 and the radiator in question is still doing the same after an hour with the boiler being on.

Thanks

James

dilalio · 16 Dec 2017

Put some cleaner in the system and focus it on the problem rad (by leaving others shut) for a prolonged period - could take a few days! Also remove the TRV head from the problem rad and make sure the pin fully extends. Also fully open lockshield on this rad. Blocked return from that rad is a potential suspect. Is it on a dropped loop?

Edit: the rad in question is not a vertical designer rad is it?

morpheus83uk · 16 Dec 2017

Thanks I do have a few questions.

What is a dropped loop? What kind of cleaner would I need and how do I put it in the system?

Its a new TRV so t should be fine but I will have a look and see what happens.

The radiator is just a normal radiator nothing fancy.

algas · 16 Dec 2017

Could be a worn pump or set to a low speed

RigidRaider · 16 Dec 2017

A dropped loop would be where the flow and return pipes come down from the first floor, for example. This could be trapping sludge.

That you have a new TRV and the rad isn't warming up should point to the new TRV being wrong. Unscrew the collar and remove it altogether - what happens now?

morpheus83uk · 16 Dec 2017

This was the issue before the new TRV was installed and its a new radiator as well. Erm possibly but the boiler has been moved in the past 3 years with new piping putting in.

I will still give it a go to see what happens.

dilalio · 16 Dec 2017

Has that rad ever worked properly?

morpheus83uk · 16 Dec 2017

No its never worked properly since we moved in.

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Cold Radiators

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