Help - problem refilling central heating system.

16 Apr 2005
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United Kingdom
Hi all, hope you can help please.

I needed to fit a new towel warmer in place of an old rad and drained down the system as per the guides i.e. (vented system - tied up the ball cock - then drained it down from lowest radiator) - this all worked fine -after opening all the bleed valves upstairs it all drained down nicely. I changed my rad valves then started to try to refill it all.

Closed all drains/bleed valves and allowed the expansion header to refill with water. Then opened a few bleed valves upstairs and got nothing thru.
I went downstairs and found all but 2 rads had water in and bled ok. The final two had nothing in and did nothing with the bleed valves open.

I then tried various combinations of bleed valves on/off but no luck.
So i'm stuck with 2 rads downstairs with no water and all upstairs. I guess I have an air lock somewhere but can't find it.

Any tips greatly appreciated - thanks in advance.

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Did you open the airvents when you drained it out.

are the air vents blocked up, stick a pin in the hole to clear them (valves Off)
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fitz1 said:
possible drip feed blocked on tee into heating.Common problem.

posible but unlikely as the tank emptied on drain down, unless the tank was full of gunge.
posible but unlikely as the tank emptied on drain down, unless the tank was full of gunge.[/quote]

Drags it in. Never dissregarde possibilities.


fitz 1 please see 10a
Thanks for the tips, I will try checking both those out. There was quitre a bit of sludgey water in the tank and I tried quickening the drain up by emptying it out with a cup - so maybe I dredged the muck up.
I'll also try the blled valves.

At the moment though I may string myself up as I just got back from Saints v Villa. Plenty beer to be had tonight - plumbing tomorrow.

Its the next morning now and I'm up so early because there was a loud whirring sound coming from my hot water pump as it seemed to be running with no water in it ! The central heating was off and I assumed (wrongly) that the hot water would be ok. Appears not.

Any how I checked the bleed valves and they appear ok and then checked the headertank for a blockage. I was able to wiggle something down the pipe (outlet at bottom of tank) from inside the tank to make sure that was not blocked and I'm now not sure where the ' drip feed into tee is' or how to clear it.

I will follow the pipes down and see if there is an obvious way to do it.
Any more advice most welcome.


Hoooorrrraaaaay 9.15 and all done! When I first tried to clear the outlet pipe from the expansion tank I was obviously not thorough enough (just used a small screw driver). This time I got a wire coat hanger and plunged it as far as it would go and hey presto ! sorted. All rads now full and bled and hot water and heating back on.

Thanks everyone for your interest and help, I am sure I saved myself a few quid on a Sunday plumber call out - thanks again.


Buggar - spoke too soon - went back to bed for an hour everything seemed fine - I could hear the watr an pump running - then load whirring nosies from the pump - looks like there is no water thru it.

It now does this for hot water and CH - I tried bleeding the rads again - they are all ok. I went and gave the outlet pipe form the expansion tank a good poke again but no good. I'm not sure of my next step now ??? Is it just an air lock or have I pushed the blockage elsewhere??


If it helps any here are some pics of the pump and pipe work.......

sorry about all this- it seems to be working again now. I reattached a drain hose to the bottom ofthe system leaving all bleed screws shut and
the header tank as normal. As soon as I started running the water thu the pump took in water and the bolier fired up. Maybe there was another blockage that got flushed thru.

Hopefulyl I'll stop bothering you now !

Trouble is you've dislodged a load of crud out of the cold feed pipe which is now distributing itself around your system!

If it works OK for now, put some money in the piggybank for a service, flush out and water treatment when the weather gets warmer.

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