should central heating refill itself ?

albalad

have just been changing a radiator for a towel warmer type , which is slightly larger than existing radiator was.

it only seems to be warming up to around 60 % capacity - even after bleeding all the air out, which is making me wonder whether there is enough water in the system.

should it top itself up automatically from the feeder tank in the loft ? (which incidentally is full of very nasty looking crystallised stuff......... not sure if this has been one of the additives)

any help appreciated , thanks

Mr_Meanie

Yes it should it top itself up automatically from the header tank.

Just give the ballcock a nudge to see if it's working or stuck closed.

You could try closing all the other radiators off apart from the towel rail for a few minutes and try bleeding it again (bleed with the pump/heating turned off)

jimbo_the_jetset

When I recently had the plumber round to do a few jobs I asked about a knocking noise on some radiators, he suggested cleaning out the system (which he says should be done every year or so).

If it hasn't been done for a while this should help improve the efficiency and will clean out any sludge in your system.

Firstly tie up the ball !!!! so the feeder tank doen't refill. Find the radiator with the drain valve (usually the one nearest the boiler). Attach a hose to this and open the valve - drain away (might speed up if you open upstairs bleed valves but only after water level is below them). Close valves. Add central heating cleaner into system (into header tank) and refill. Leave to work for a week or so (or as recommended by product manufacturer). Drain off as above. And refill, don't forget to put in X100 inhibitor. Bleed all rads and should be much better.

albalad

mr meanie , been into loft given ballcock a nudge.... all seems ok
might have to wait until later , till heating goes off to bleed them again.

not entirely sure how to turn off pump as it is wired directly into a fused spur , i could isolate it using the gate valve directly underneath pump(grundfos ups15-50)

Mr_Meanie

albalad wrote: »

not entirely sure how to turn off pump as it is wired directly into a fused spur , i could isolate it using the gate valve directly underneath pump(grundfos ups15-50)

Sorry I didn't explain that very well.

Don't try to bleed the radiator when the heating is switched on as you might suck more air in to the system, bleed the radiator when the heating is switched off as the pump will not be running.

Canucklehead

Hi

Are you sure the pump is wired to a fused spur??This doesn't sound good at all if it is, the heating system should be controlled by one fused switch or plug (fused @3 amps)and all the controls (pump, motorised valve, boiler, room and cyl stat should be interconnected to work with each other. The way you describe it the pump will be working 24/7, which might explain the muck you have in the expansion tank. It could also just be a flex outlet to the pump.You should take some time to work out how your system is wired.
Regarding the air problem I suspect your cold feed is blocked and it will not fill at all. You could try draining some water out and see if the expansion tank fills , if it doesn't then it's blocked. Usual point to block is the tee where it enters the system with luck it's in the tank so try there first.
Good luck.

Corgi Guy.

ANDY597

Have you had a boiler change recently. Is the header tank in the loft still actually in use. Im just thinking out loud but if youve had it recently upgraded to a combi or similar it might now be filled with mains pressure from a valve near the boiler making the header tank redundant.

Corgi Guy, can you confirm ?

Canucklehead

Hi

Unfortunately anythings possible even though most installers would have taken out redundant pipework etc. I would think it unlikely in this case .
OP seems to have moved on so we'll just have to guess!

Corgi Guy.

albalad

hi guys
sorry for the delay in replying,
you are indeed correct canucklehead , its not a fused spur , but rather a fused socket with 2 cables(boiler and pump) going in and 1 coming out to a plug( which i couldn't see previously )

The problem is slowly being resolved ,radiator is now almost 100% hot - i had been trying to bleed radiator while it was hot , hadn't realised it would make such a difference.

Andy597 , thanks , but boiler is around 6-7 yo. and tank is still in use

Canucklehead

Hi

Glad it's almost there!!

You might find that the cold feed is 99% blocked , if you do a bit of investigating as to where the pipework is and where it tees into the system you might save some time in the future. You know how these things always happen on a cold Sunday?!

Corgi Guy.