Low water pressure in Bolier only after turning on heating

manan.shah.82

Hello,

We have Worcester combi boiler in our house. I had service done about 6 months ago and everything was normal.

During the summer we never turned on heating but I turned on heating about few days ago and then I saw low water pressure (bar on pressure gauge was at 0)..so i turned on the tap/hose and pressure gauge was around 1.5..next day I turned on heating and same thing happened

I thought there must be some air in radiators because we didn't use them for a while so bleed all the radiators..there wasn't any hissing and water started dropping so I immaterially turned off the radiator valve...

I didn't see any leakage around the radiators but shortly after turning off the heating pressure bar went to 0 again..

Can anyone suggest me what can be wrong?

Please note, radiators were heated properly and hot water is also coming. I noticed that when I turned on heating pressure bar went over 2.5 in Red but I guess it's not that bad.

at the moment I manually fill up the pressure level but I should be doing this every time and I assume there must be something wrong but clueless where

Thanks.

System

It sounds like a problem with the expansion vessel and probably needs to be repressurised. We had a similar problem and after repressurisation all is fine

macman

Is water escaping from the PRV via the overflow pipe to outside? Could just be a bit of grit in the PRV.
Worst case is that you have a leak somewhere on the CH circuit itself that is not visible.

southcoastrgi

+1 on re-pressurising the expansion vessel

manan.shah.82

!!!!!! wrote: »

It sounds like a problem with the expansion vessel and probably needs to be repressurised. We had a similar problem and after repressurisation all is fine

I have no idea where expansion vessel is located or how to re-pressurise it but will check the manual and see if it helps.

Thank you very much.

keystone

DHW side of combi boiler isn't a sealed/pressurised circuit. Thats why you noticed nothing when you were only running hot water.

When you find the EV it will have a schrader valve (just like the one on your car tyres) on it. Press the centre pin down. If air comes out repressurise. If water comes out the diaphragm is knackered and you'll need a new EV.

Cheers

macman

Usually at top rear of the boiler, and often a pig to access.

southcoastrgi

to re-pressurise the EV the boiler can't have any pressure in it so normally i would turn off the valves underneath (if it's a combi or drain it if it's a system boiler) open the boiler drain off if there is one or the prv if there isn't & leave it open while you pump the EV back up, you also need to check the pressure it needs to be it will tell you in the MI or on the side of the EV some need to be 3.5 bar & to do that you need a foot pump or electric pump you won't do that kinda pressure with a bike hand pump.

Canucklehead

Hi.

When the boiler was serviced was the EV checked?
If not then it should have.

You will not notice a great rise in pressure from DHW alone as it only heats a few litres of water in the boiler.
On c/h all the system water is heated resulting in a greater pressure rise.


The model of Worcester is.........?


GSR

manan.shah.82

Canucklehead wrote: »

Hi.

When the boiler was serviced was the EV checked?
If not then it should have.

You will not notice a great rise in pressure from DHW alone as it only heats a few litres of water in the boiler.
On c/h all the system water is heated resulting in a greater pressure rise.


The model of Worcester is.........?


GSR

it's Greenstar 24i Junior....I don't know whether guy checked EV during the service or not but he did plenty of things so I think he must have checked it...though I don't know where ev is located and how to pressurise it so I can't be sure whether he did or not

manan.shah.82

southcoastrgi wrote: »

to re-pressurise the EV the boiler can't have any pressure in it so normally i would turn off the valves underneath (if it's a combi or drain it if it's a system boiler) open the boiler drain off if there is one or the prv if there isn't & leave it open while you pump the EV back up, you also need to check the pressure it needs to be it will tell you in the MI or on the side of the EV some need to be 3.5 bar & to do that you need a foot pump or electric pump you won't do that kinda pressure with a bike hand pump.

Thanks for the information but what is prv? and to be honest I don't know where EV is located? how can I find it out?

I had a look at the manual but couldn't find anything helpful..

considering I have no idea about it should I call some corgi certified engineer for this or is it something really simple which anyone can do? I don't want to spend much money on simple thing but at the same time I don't want to make things worse...