Air block / no pressure in CH system

[Tommy J]

Hi All,

bit of a long one so my appologies.

I wanted to take the rad off in my kitchen but one of the valves was stuck so I thought I'd try to draing the system and replace the valve and rad at the same time.

I proceeded to drain the system but only got a bucket full of water.I tried opening the bleed valves upstairs and only a little more water came out.
I checked the header/expansion tank and that was full. I spoke to a friend (plumber) who came round and fitted some isolation valves on the pipes for the new rad and said I should be able to use the hot water still and he left.
However because the system is only half drained, I now have a load of air in the system which I can't get rid of and it seems the boiler/pump can't pump it round. The boiler kicks in but only for about 10 seconds, then won't fire up for another 20 mins.

Can anyone suggest how I can force the air out or more water into the rads from the header tank please? The pump is working overtime and is extreamly hot although the pipes everywhere are stone cold.

Many thanks,

Tom

 

[45yearsagasman]

Try draining the system and checking the water level in the fill/exp tank in the loft.If water level remains full and the ball valve doesn't drop then you have a blocked cold feed pipe. Trace the feed pipe from the tank to where it joins into the system and around that area is where to look for a blockage.I'm surprised that your plumber did not investigate this problem when he was on site?

 

[Tommy J]

thanks '45yearsagasman', I tried to check the pipes just by gently tapping, but it appears the pump either has something stuck in it, or it's decided to finish cooperating.

Either way it looks like I'm going to have to result in calling the cavalry.

Could anyone tell me if it's possible to undo the cover of the "grundfos selectric 4 pump" to see if it's broken or would that result in water squirting everywhere )

Many thanks for your help.

Regards,

Tom

 

[ducatikid]

Please don't take me the wrong way here (!) but as you are calling someone in for possible blocked cold feed , or certainly to clear your airlock , I would leave well alone and get them to check the pump for you as well. good luck

 

[Tommy J]

Please don't take me the wrong way here (!) but as you are calling someone in for possible blocked cold feed , or certainly to clear your airlock , I would leave well alone and get them to check the pump for you as well. good luck

Very true, just thought if it's a case of knackered pump, I might be able to clear the blockage, but maybe not, might just leave it.
thanks