# Cold radiators



## MrGrumpy (27 Nov 2020)

Looks like I need to do sort an air lock in the central heating system. System was drained down twice when we had bathrooms done up. Now looks like the plumber didn't bother his @rse to actually check all was ok. Got two cold radiators at the other end of the house upstairs. Did bleed a fair amount of air out of the others and had to top up the system. Oh well that`s what I`ll be doing this afternoon.


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## figbat (27 Nov 2020)

After a drain-down and refill you often have to go chasing air out of the system as the incoming fresh mains water will have dissolved air in it, which is released over time. With ours it always trips the boiler off for a day or two after a fresh fill but once the air is bled off it never comes back (until the next refill).


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## I like Skol (27 Nov 2020)

MrGrumpy said:


> Oh well that`s what I`ll be doing this afternoon.


30 minute job. Takes that to do my 3 storey, 4 bed semi. It is always the same 2 or 3 radiators that catch the air but I always check them all just to be sure.
If you tell the misses it will take all afternoon you can sneak in a couple of hours talking bollix on the forum....


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## GlamorganGuy (27 Nov 2020)

My boiler is working OK but only a couple of radiators in my house are actually heating up. Have bled them all and there seems to be no air at all in the system. Tried turning the working ones off in an attempt to encourage water to flow into the cold ones but it doesn't work. Anyone have any suggestions?


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## I like Skol (27 Nov 2020)

Pump gone? Could just be convection heating a few radiators on the path of least resistance. What type of boiler have you got?


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## GlamorganGuy (27 Nov 2020)

Hmm sounds like that could be it. It's a Vaillant Thermo Compact, around 15 years old. Have had a new pump in the past few years but of course that's no guarantee that it hasn't gone kaput again.


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## MrGrumpy (27 Nov 2020)

GlamorganGuy said:


> My boiler is working OK but only a couple of radiators in my house are actually heating up. Have bled them all and there seems to be no air at all in the system. Tried turning the working ones off in an attempt to encourage water to flow into the cold ones but it doesn't work. Anyone have any suggestions?


Might need balancing if no air. You need to shut down all radiator valves plus lock shields . Then open up slightly one by one with heating on till you get the cold rads warm.


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## Electric_Andy (27 Nov 2020)

Also worth remembering that you might have to add some more anti-corrosion additive if you've drained a lot out


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## screenman (27 Nov 2020)

GlamorganGuy said:


> My boiler is working OK but only a couple of radiators in my house are actually heating up. Have bled them all and there seems to be no air at all in the system. Tried turning the working ones off in an attempt to encourage water to flow into the cold ones but it doesn't work. Anyone have any suggestions?



Do those rads that are not working have thermostat valves on?


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## GlamorganGuy (27 Nov 2020)

screenman said:


> Do those rads that are not working have thermostat valves on?


Yes all the radiators have working valves (except one that's stuck in the "on" position... and it's the only one that's working)


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## screenman (27 Nov 2020)

GlamorganGuy said:


> Yes all the radiators have working valves (except one that's stuck in the "on" position... and it's the only one that's working)



Top off and pull the pin up, they often get stuck down during the summer, long nose pliers will do it.


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## I like Skol (27 Nov 2020)

screenman said:


> Top off and pull the pin up, they often get stuck down during the summer, long nose pliers will do it.


All of them at once? Would be a hell of a coincidence.


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## screenman (27 Nov 2020)

I like Skol said:


> All of them at once? Would be a hell of a coincidence.



Only 2 not working as I read.


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## MrGrumpy (27 Nov 2020)

screenman said:


> Only 2 not working as I read.


That would be me but my trvs are working , I just have no hot water even to the pipes !I have my plan for this afternoon.


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## fossyant (27 Nov 2020)

I've found shutting off all the other rads to force the air out of the problem rad works, then open up on by one after a system drain down.

We're lucky, in that air only ever collects in one radiator in the house, and I just bleed it once every 6 months.


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## screenman (27 Nov 2020)

MrGrumpy said:


> That would be me but my trvs are working , I just have no hot water even to the pipes !I have my plan for this afternoon.



So you have had the tops of and moved the pin up an down using pliers?


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## MrGrumpy (27 Nov 2020)

Yep , they were only fitted last year


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## MrGrumpy (27 Nov 2020)

Doesn’t seem to want to shift ? All rads closed off on lock shields and temp set to max ! Should be moving air now ?

edit sometime later 

well think I’ve worked out what’s happened. The bathroom fitter I got is an absolute clown. When he moved the radiator in the bathroom when we had it done up , it looks like he has not continued the circuit into the next bedrooms . Hence a short circuit!!  . The towel radiator has been made the last radiator. It might be recoverable without too much grief I hope. However I’m f.....in ragin. Was recommended to us , this is not his first mistake on this job.
Anyway he is coming tomorrow to hopefully fix but he better bring ear defenders as my wife is ready to go through him.


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## Globalti (29 Nov 2020)

It's not air, it's hydrogen, which is the by-product of oxidation inside the steel radiators. Did you add inhibitor last fill up? This is just a soap, which makes the water alkaline to prevent corrosion. 

You should be able to ignite the hydrogen as it hisses out of the bleed screw.


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## MrGrumpy (29 Nov 2020)

Think your replying to the OP, however that’s an interesting post , didn’t know that !!


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## Gunk (29 Nov 2020)

Easiest solution is to check the simple stuff first, unscrew the TRV and make sure the pin underneath moves freely, you want it in the up position (needle pliers are ideal for this) if this is OK check the other side and undo the valve slightly to increase the flow.


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## Phaeton (29 Nov 2020)

Just remember never to shut all the radiators off at once, you must have at least one open, systems should have one radiator without valves


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## MrGrumpy (29 Nov 2020)

Question do you need to balance radiators in a pressurised heating system ?


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## Phaeton (29 Nov 2020)

MrGrumpy said:


> Question do you need to balance radiators in a pressurised heating system ?


You should


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## irw (30 Nov 2020)

Globalti said:


> You should be able to ignite the hydrogen as it hisses out of the bleed screw.


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## Hicky (1 Dec 2020)

Have a google and get some way of testing the in/out temp of the rads, aim for a 10-12deg drop across them.
We've had plumbing work done and the "plumber" was shite, back three times for work not done and none of the rads balanced, fortunately apart from my Ms none of us are nesh and we don't have the heating on very much at all as the house is both well insulated and the back of the house being south with many windows tends to provide most of the needed heat when Rochdale is sunny.


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## Mr Celine (2 Dec 2020)

If the radiators are connected with microbore pipes (8mm or 10mm) the pipes can get blocked with corrosion debris, particularly if the system has been disturbed.


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## MrGrumpy (3 Dec 2020)

Hicky said:


> Have a google and get some way of testing the in/out temp of the rads, aim for a 10-12deg drop across them.
> We've had plumbing work done and the "plumber" was shite, back three times for work not done and none of the rads balanced, fortunately apart from my Ms none of us are nesh and we don't have the heating on very much at all as the house is both well insulated and the back of the house being south with many windows tends to provide most of the needed heat when Rochdale is sunny.


Radiator balancing not an issue with a pressurised system ? Also with TRVs fitted ? However if it still needs to be done I will give it a go.


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## I like Skol (3 Dec 2020)

MrGrumpy said:


> Radiator balancing not an issue with a pressurised system ?


Never had to do it here with TRVs over 3 floors. Only thing to remember is I have always been advised to have at least one rad just fitted with lockshields set fully open so there is always a flow path and the boiler isn't pumping against a shut loop. Towel rad in the bathroom is a good choice so you always get dry towels even if the house is warm.


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## Hicky (3 Dec 2020)

MrGrumpy said:


> Radiator balancing not an issue with a pressurised system ? Also with TRVs fitted ? However if it still needs to be done I will give it a go.


It depends how big your house is/how many rads. It doesn’t hurt to make it slightly more efficient, with a reasonable pump/boiler it doesn’t take much closure of the lockshields compared to a gravity fed in which it’s more important.


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## MrGrumpy (3 Dec 2020)

18 radiators , may try tweaking at the weekend .


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## Poacher (3 Dec 2020)

screenman said:


> So you have had the tops of and moved the pin up an down using pliers?





Gunk said:


> Easiest solution is to check the simple stuff first, unscrew the TRV and make sure the pin underneath moves freely, you want it in the up position (needle pliers are ideal for this) if this is OK check the other side and undo the valve slightly to increase the flow.


Take care when pulling the pin plunger up with pliers. I once pulled a pin right out of a cheap (Wickes) TRV. That was quite an, er, _interesting _experience. Probably much less likely with a decent, e.g. Danfoss one.


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## Archie_tect (4 Dec 2020)

I love bleeding radiators with my bleeding radiators key... the thrill of the first sudden splurge of water as the air escapes and the panic to shut the little valve... bliss!


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## MrGrumpy (5 Dec 2020)

Ok what’s the small valve that adjusts ? Could that be used to balance the hot water for the CH between upstairs and downstairs ?


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