How doe I fit an expansion vessel to a new central heating

24 Jun 2009
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Newcastle upon Tyne
United Kingdom
I have just installed a new central heating system in a refurbishment project that i'm doing and I fitted an Ecotec 831Plus combi boiler. I have installed column radiators which has meant that my system volume is approx 150litres - (I drained down the system and got 130 out so added 20 litres for what would be left in the pipes). The boiler instructions says an additional expansion vessel needs to be fitted on the return for all systems with a capacity over 100litres as the expansion vessel in the boiler is 10 litres. - it recomends 24 litres for a 150 litre system.

Can anyone advise / recomend which expansion vessel I should fit and if I need a PRV, pressure gauge, and filling loop on it or would the PRV and pressure gauge in the boiler do the same job with the PV filling from the CH system? I assume the vessel just needs to be Tee'd into the 22mm return pipe under the boiler.

Any advise / recomedaitons would be greatly appreciated as I've never fitted a PV before
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I have just installed a new central heating system in a refurbishment project that i'm doing and I fitted an Ecotec 831Plus combi boiler....

I take it you have not been a RGI very long, you might want to get access to Combustion Chamber section of the forum; sometimes you don't want to ask embarrassing questions for the world to see.
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Thanks for the help.

When you say correct can you be more specific with regard to the PRV, pressure gauge and filling loop requirments. What do I need with regard to fittings between the top ov the PV and the return pipe

For the record I'm not a RGI (purely an amateur plumber) - so not embarassed :)

Are there larger combi boilers available than an ecotec 831?
If you need to ask shuch basic questions there is always a fear that you have not fitted the boiler and its gas supply properly.

One also wonders how you are going to commission it, do the paperwork and notify Building Control.

The air pressure in the new EXV needs to be set to about 0.9 Bar before you fit it. Thats assuming you will pressurise the boiler to about 1.5 Bar.

If you have installed the rest of the system properly then you already have a functional PRV and don't need another one.

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