How to drain a combi boiler?

[novicetiler]

How to drain a combi

I was wondering if anyone could give me advice on changing a couple of radiators on a combi system. I have done this before on a conventional system but never with a combi.

What I am planning to do is, turn off the power to the boiler then isolate the cold supply.

Then close off the radiators that I am not changing (to save draining them). Then drain off the two radiators in question ( I guess I should also open the bleed valves on them).

After replacing them with bigger radiators complete with thermostats I will then re pressurise the system to one bar before opening the valves on the radiators I didn’t change (is that the right way round?). Hopefully the boiler should then work…or not?

another thing I am also not sure about is whether I should bleed the pump (which I presume is in the combi boiler somewhere!).

Does this sound like a good plan? Or am I making a terrible mistake, any help whatsoever on changing radiators with a combi boiler would me most gratefully accepted

Many thanks!
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[compheat]

You seem to have it worked out ok. you need to open up rad valve's and vent them before you repressurise the system this should stop any airlocks. The boiler will have auto air vent so the pump should be ok.

 

[novicetiler]

Dear compheat
thanks for reply. When you say "Vent" the radiators am i right in saying: after draining i should make sure all the valves and bleed nipples are open - is this what you mean? after that, i would close the bleed nipples and begin re-pressurising? Sounds good to me.

cheers
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