Refilling CH system

[Greg]

I seem to have a challenge in refilling the CH system after draining it down. My method is to close all the air valves etc., turn on the water, wait until it fills. Then I bleed the air from the radiators and turn on the pump/heating. At this point, I hear lots of glugging in the boiler part of the system, as if it was previously closed off to the water until the pump/heating is turned on.

I have turned the screw cap in the centre of the pump to then bleed the system again, and then bleed all the radiators again to get rid of residual air in them.

However I'm not convinced I'm getting all the air out of the system near the boiler as I get some overheating issues on the boiler (it goes away again when I drain and refill the system, pointing to an airlock).

Am I missing something? Is there a way to open the valve in that area of the system to fill it up before turning it on?

Thoughts on technique or other appreciated Thanks

[Bob Minchin]

Your method sounds normal to me. Some systems are just pigs to refill. One thing you could try is to fill from the drain c*ck via a hose. This can be messy if your drain c*ck(s) are indoors and are the type without sealing glands to be careful if you try this. You could alway fit a bleed valve somewhere near the boiler. Try running the pump before switching on the boiler if you have that degree of control and bleed before adding heat if that might help. Have you got zone valves that only open when the boiler is running?

hth Bob

[F]

I usually leave the 'highest' one open to allow the incoming water to push air out of the system.

[John]

You can't fill the system if the air valves are closed. As the system fills you need to be bleeding each and every radiator.

Does the boiler have an automatic bleed valve on it - if so - it may have a cap on it. The needs removing to allow it to work.

[John]

Post the name of the boiler - someone will have one the same and will confirm if there is an auto air vent that may need uncapping.

[F]

I think that's what I was telling the OP...

[Greg]

Didn't see an automatic bleed valve, but the boiler is a Baxi Barcelona.

Thanks

[John]

Sorry - you said (just) the "highest" one. This would leave air trapped in every other radiator (assuming they are conventionally plumbed and the bottom.

[F]

I assumed that the OP would realise that after 'the highest' was full of water, then the rest would have to be bled in turn.

However, when I drain the system down I turn off the valves at both ends of every radiator that may empty, apart from the highest, before I start draining. That way all radiators bar that one are full and refilling is much faster and simpler.

[John]

Good idea - and saves introducing more lime.

[F]

Also saves on inhibitor.

[John]

I have tried searching for instructions to your boiler - without success. Are you absolutely sure you can't find an air vent on the top of the boiler (inside on the heat exchanger). I believe most have one.