How to recharge an expansion vessel in a combi boiler

[47represent]

shouldnt you close the flow and return and leave the prv open while doing this?

[ultimatehandyman]

@47represent

Why?

[47represent]

@ultimatehandyman because you woun't get a true reading, cos your puttin air in and theres nowhere for the water thats still in the expansion vessel to go. Thats what I got told at work anyway. I know that after drainin down there's still water in the exp. vessel from my own early (wet) experience

[ultimatehandyman]

@47represent

If there is any water left in the expansion vessel it will be forced into the pipe work for the central heating. There will not be enough water in the system to pressurise that side of the expansion vessel so you should get a true reading.

[MrJackanorim]

prv normaly needs removing and cleaning if the vessel was flat aswell, or replacing

[ultimatehandyman]

@MrJackanorim

I once got a boiler engineer out to fix a problem with this boiler and he drained the system via the PRV, after that is constantly dripped until I got another engineer that fixed the boiler and serviced the PRV.

[MrJackanorim]

@MrJackanorim yeah idealy you shouldnt drain it from the prv, some boilers dont have drainoffs though or a drainoff on the radiator so sometimes you have to use the prv as its alot easyer to drain and you no you will get rid of nearley all the water in the boiler were if you just use the external drainoff you might not, depends on the boiler realy. plus if it was because the vessel was flat the prv needs changing 9 times out of 10 anyway

[qwertyytrewq103]

An ordinary bicycle pump will do for pressurising vessel , from experience discharge system of water pressure empty vessel of air and give 30 full strokes of a bicycle pump thats in good order.

[goodcrac2]

That's a remote vessel. You'd never get that pump in the back of that Ferolli.

[ultimatehandyman]

@goodcrac2

Yes it is a remote vessel, as it is impossible to film in it's position.

That pump will fit the schrader valve on the boiler as it is right at the bottom.

[igbhd]

thats a nifty little gadget

[ultimatehandyman]

@igbhd

Yes, it is really handy.

I bought it from an ebay seller a few years back, but they don't seem to be made anymore!