Downstairs radiators - only work when I hit them!

[mrobbo]

Hi all,

My home has five radiators - three upstairs, two downstairs.

The upstairs radiators are fine. However two downstairs rads remain lukewarm or even cold, when the heating is on. However, if I 'tap' each rad along the bottom of it, both then warm for... for about 24/48 hours... before cooling again. I then have to repeat the process to get them to warm again.

Any ideas what the issue is? My guess is sludge in the system?

Thank you!

 

[wheeto]

Do the rads in question have thermostatic valves? These can sometimes stick, requiring a nudge to unstick them.

Alternatively do you hear any gurgling noises as the rads warm up? It's possible - unlikely! - that your system is drawing air in, creating an airlock which you shift by tapping the pipework.

Is it a sealed (pressurized) system or open vented?

 

[mrobbo]

Hi Wheeto,

One radiator has a thermostatic valve (this radiator is only two years old), the other does not. It is a sealed system, and no gurgling noises to report! Hope this helps?!

 

[wheeto]

Hope this helps?!

Ha ha, not really

Unless the two rads are piped in series, or there's a permanent blockage (if it's a one-pipe system) under one of them, I can't see how a fault with the TRV would affect both of them, or for a tempoary blockage to keep appearing on the downstairs circuit which is moved by tapping on a rad???

When they go cold, can you "revive" just one of them?

 

[mrobbo]

Yes, if I tap one of them but leave the other alone, it's get hot (albeit temporarily) and the one not tapped remains cold.

Let's just say there is sludge in the bottom radiators. Wouldn't tapping the rad disturb the sludge and allow the hot water through, then the sludge settles back down, meaning further blockage? That's all I think is happening to be honest...

 

[HoodedClaw]

Sludge is generally a cold spot that is in a curve shape at the bottom of the radiator, a few inches at the edges, 10" or so in the middle, to move sludge when flushing you hit it with a mallet (I have an attachment for my SDS drill that bashed the heck out of it) - I wouldnt have thought a gentle tap is going to move sludge unless its just settling at the pipes..

Have you bled them?

do they only get 'warm' or 'hot' - as hot as upstairs?

Are the valves fully open?

Presume the pump is on full to test it - though with just 5 rads I cant think it really need to pump hard!

 

[mrobbo]

Hiya,

Well it's more of a 'hit' than a tap!

I've not bled them yet, but am planning on doing so tonight. Do I bleed all 5 rads or just the troublesome two?

Valves are fully open - I've not tampered with the upstairs rads as they are fine. Yes, the pump is on when I test.

When left alone, the downstairs rads get slightly lukewarm at best, whilst upstairs get very hot. After some 'persuasion' (hitting each rad along the bottom firmly), both downstairs rads match the upstairs rads for heat, then cool down over about 24/48 hours. Both pipes leading to both rads are hot even when the rads themselves are not.

 

[HoodedClaw]

Ok, the next step I'd try in to close of the upstairs rads, see what happens then. Hopfully downstairs will get hotter - making it more a sludge problem or blocked pipe, then drain of some water and put a bottle of sludge remover in the system, if you have a towel radiator take the top off that and pour it in, if not get the cartridge one and squeeze it in the rad vent, pressurise it back up and let that run around for a few weeks, drain it all down, flush it through - one rad at a time, and it may be ok again.

Most pumps have 3 speed settings, not just on/off. you should see it clearly with just the front cover of the boiler, no need to touch anything else.

 

[mrobbo]

Hi HoodedClaw, thanks for the help. I am getting a mate round tomorrow as I am no good at this sort of thing, and together we'll try and do as you've suggested. I'll report back with results.

 

[mrobbo]

Hi, quick update on my issue. The rads have been balanced now so that the downstairs rads now get hotter. The upstairs rads are not as hot as they were, although this is a good thing as they were all blazing hot previously - too hot in fact.

I understand though that this may only be a temporary solution and that I may well have a sludge problem. HoodedClaw, thanks for the advice above. I will try getting some sludge remover and try what you've said. Thanks a lot.

 

[Reg Man]

If you too have been effected by villant abuse to your radiators, phone the abused raditor help line free on 0800...........LOL

 

[HoodedClaw]

No problem mrobbo, if it works feel free to hit the thanks button on my post, its how we get smiles for helping people out

 

[mrobbo]

Ah yes, where are my manners haha.

Done!