Draining a Sealed CH System

17 Nov 2005
Reaction score
United Kingdom
Hi all,

Due to some building alterations (knocking 2 tiny Bedrooms into one) I need to change the position of 2 radiators in my house. I am doing the work myself as I have previous building experience, but I need some advice on the plumbing front. I have drained vented CH Systems several times before, but never a sealed system.

I have a Baxi 105e and have checked the Baxi website for advice but they never mentioned how to drain/refill the system. Can any of you give me a run down on how to empty and refill my CH system please.

I would be very grateful for any help you can give me.

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Turn off boiler ( make sure filling loop is not connected)
Open drain at lowest point
Open rad bleed valve or two at high point.
Do pipework
close drain
fit loop
fill system.
Pressurise to 1 bar... Or whatever you boiler instructions say.

At least that has always worked for me ( i'm NOT a plumber )

Of course all the above may be a load of B******s
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Cheers for the advise lads, I am going to flush it through with some fernox and then drain and refill it again with inhibitor added. Be lucky!
decthemech said:
Cheers mate,

Do I need to do anything other than fill the system with the filling loop to pressurise it?

No just make sure you dont overpressurise the system or you may end up with a weeping pressure realease valve....

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