DIY Doctor UK DIY Forums

Okay, sorry if this seems to be a really stupid question but I'm going to remove a radaitor for decorating (which I haven't a problem with). The thing I've been pondering is how does the system top itself up to replace the water lost from the removed radiator. This has made me think after reading the manual to my Boiler where it mentions being a sealed system and cannot find no mention on what to do if any part of the system is interupted. I have an Alpha CB28 combi-boiler by the way, no tanks in the loft or anything, everything's direct from the mains.

Not a daft question, just one you don't know the answer to.

Sealed systems will usually have a filling point called a filling loop. You use this to top up, whilst bleeding the radiator of air. The system pressure usually need to be at 1bar when cold, this is indicated on the boiler pressure gauge usually.

Hope this helps,

AH

use the fill loop to top up the pressure just above 1 bar

It doesn't refill itself, you have to re-pressurise via the combi fill loop.


htg

thanks for your reply, I had a funny feeling that this was the answer

Another question if anyone could offer advise. Found the fill loop easily so no problems there. Just wondering what the sequence of events are once the radiator is reconnected. Do I?:

1. Leave boiler off?
2. Reopen both radiator valves?
3. Bleed radiator whilst repressurising system or repressurise then bleed.

Sorry if this seems a simple question to some but I've never had experience of sealed CH systems in any of my previous houses, they've always refilled themselves from loft tanks.

Thanks again

exactly as described.

refit rad, open valves, pressurise the system to 1.5-2 bar and close off the filling loop, then bleed rad. keep doing until radiator is full and system pressure is at 1bar or whatever your MI (manufacturers instructions) state.