Upstairs radiators won't fill up after draining

8 Nov 2010
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United Kingdom
I know it's Sunday but I'm hoping there is someone around to stop me from having a nervous breakdown!!

I have drained my system to carry out some work. When I drained the system I did so from the bathroom radiator as I didn't have a drain cock anywhere. This drained the bathroom radiator and upstairs, but I have to drain the other 3 downstairs radiators individually.

I think I have a header tank in the loft, but access is very restricted and I can't really get in the loft, so was unable to tie up ballcock and could only stop the flow to the header tank by turning off the mains water supply.

I have done all of the work and got all the rads back on the wall, turned the mains water back on but I only have water filled to the radiators downstairs.

The upstairs rads are hissing lots of air but I just can't for the life of me get them to fill up with water.

When refilling I had all TRV's and lockshields open with the bleed valves closed.

The downstairs rads took forever to fill, in fact they were empty this morning and I turned the water back on at 9pm last night.

The downstairs ones only filled when I turned the gate valve off coming straight from the boiler.
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Air taps on rads partially blocked maybe and just taking a long time to fill up? Ive had to wait 20 mins per rad on some systems.
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Try a mirror on a stick to look in the header tank if it still has any scum and looks dirty chances are it did not drain, as said blocked down-feed.
I've managed to get in the loft and get to the header.

It's got water in and pushing the ball cock down is letting water in but the bottom of the tank is full of gunk.

I've back filled from downstairs and have got water in all rads.

Turned on boiler. None of the radiators are getting any heat. Flow and return pipes stone cold on all radiators.

Any ideas before I call in the pros?
Quick update.....

I've got to the pump and turned the screw on the front and water came straight out and no air.

Turned on boiler why I still had access to the pump and flow got really hot but the outlet from the pump didn't get hot.

So I gave it a gentle tap with a hammer and the water then flowed through the pump and reached the flow of the first rad but the hot water didn't flow into the radiator.

Any ideas now?
Sooner or later you are going to have to clear out that blockage in the F&E.

How long to you want to spend trying other things before you do that?
I just thought I was trying to rule out other things, namely and airlock, before I went ahead with trying to clear the blockage.

To be fair, going through the process of accessing the tank and finding the pump hasn't done me any harm as I now know they are accessible when I need to get them again.

Is there any chance a re-drain and a refill might clear the blockage or is it a definite cut the pipe job?

If it's a cut the pipe job then can I use push-fit to replace the section of pipe or does it need to be soldered?

Now I understand fully where the header tank is and where the pipes come from out the loft, I can trace the likely source of the blockage so I'm happy to give it a go.
you could try draining and refilling, but that often entrains more air. find the cold feed connection and cut it out.

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