Draining the system

[moosehead]

Need to do some minor work on our CH system.

I have drained the systme before so am quite confident in carrying this out, however, I want to try to minimise the quantity of residual air, post re-fill, requiring bleeding. The reason why I say this is that the last time we drain/re-filled it seemed quite a lot of air may have collected in the boiler causing banging during boiler heat up. (Banging now ceased)

Is there any way to re-fill with minimum residual air? This is a pumped system with 3 way valve. We have what appears to be a pressure relief valve on a pipe leading off the pumped circuit. This has a small plastic knurled knob and an allen keyed screw. Can I open this to help relieve the air during refill or even during the bleed whilst running process.

Would appreciate any advice.

 

[Newboy]

Depends on the work that you want to do - close all the rad valves / partial drain down / freeze relevant pipework

 

[ollski]

why does it need draining down?....most jobs can be done with a couple of bung kits.

 

[moosehead]

Work is moving some pipes for a bathroom radiator, but I also believe the system needs a flush.

Any ideas?

 

[hotncold]

I read an article about re-filling the system from below rather than above.
i.e. Taking a hose from the cold water mains and connecting to the drain valve and re-filling it carefully under pressure.
I wonder if anyone has any comments on this procedure...........before I try it myself.

 

[ollski]

I read an article about re-filling the system from below rather than above.
i.e. Taking a hose from the cold water mains and connecting to the drain valve and re-filling it carefully under pressure.
I wonder if anyone has any comments on this procedure...........before I try it myself.

you might have to if you got a blocked cold feed

 

[ChrisR]

Had to do exactly that yesterday because the pump didn't have any water in it to pump round. Worked quickly - but leaked a bit in the process of course.

Don't forget to bleed the pump, and start with the 3 way valve on the "Man" setting, which holds it open.

 

[keego]

I've fitted a gate valve on the cold feed to my system (yes I know you shouldn't but I know it's there & what it's for), when I need to work on my system I close the gate valve & put a 22mm speedfit stop end on the open vent. Better than any bung kit.