Boiler - Main System 24HE - Over Pressure Issue

[U.P]

Hello all,
hoping some clever people will be able to help my nephew in his new home?
Fault:
Main System 24HE Boiler (not combi) Tank in loft & HW tank in bedroom
Boiler pressure is too high, at rest & not in use it is sitting at 2.5 bar & the external wall overflow pipe is constantly running (recommended 0.5 - 2.5 bar range on boiler)
We have released the pressure from the system (release valve) to 0 bar, then in a relatively short period of time the pressure returns to 2.5 bar & the external overflow is running water again (boiler is not calling for any heat at this time)
If we turn boiler on for Hot Water (for example) the pressure will raise up to 3 bar & it would seem that the external overflow pipe Stops from running water! (we do get the hot water)
If anyone has any informed ideas of what is causing this issue they would be much appreciated & thank you for any help.
(sorry pics are a little blurred but away from the property now)

 

[fixitflav]

Hello all,
hoping some clever people will be able to help my nephew in his new home?
Fault:
Main System 24HE Boiler (not combi) Tank in loft & HW tank in bedroom
Boiler pressure is too high, at rest & not in use it is sitting at 2.5 bar & the external wall overflow pipe is constantly running (recommended 0.5 - 2.5 bar range on boiler)
We have released the pressure from the system (release valve) to 0 bar, then in a relatively short period of time the pressure returns to 2.5 bar & the external overflow is running water again (boiler is not calling for any heat at this time)
If we turn boiler on for Hot Water (for example) the pressure will raise up to 3 bar & it would seem that the external overflow pipe Stops from running water! (we do get the hot water)
If anyone has any informed ideas of what is causing this issue they would be much appreciated & thank you for any help.
(sorry pics are a little blurred but away from the property now)
View attachment 232205 View attachment 232204 View attachment 232206

Sounds to me like the fill valve from the mains is open. By overflow, do you mean from a pressure relief valve? The water must be coming from somewhere.

 

[U.P]

Hello
just working out how this site works! Yes the 'overflow' is from the pressure relief valve (we think) the copper pipe in the picture. I agree that the water is coming from somewhere, however could not quite locate a 'fill valve' (i'm aware of the fill/top up valve/loop on a combi boiler) The installation instructions say to fill boiler & shut off valve however x3 of us could not find such a valve? However it does seem like something is not controlling the pressure?
Thank you for replying to my post

 

[fixitflav]

Hello
just working out how this site works! Yes the 'overflow' is from the pressure relief valve (we think) the copper pipe in the picture. I agree that the water is coming from somewhere, however could not quite locate a 'fill valve' (i'm aware of the fill/top up valve/loop on a combi boiler) The installation instructions say to fill boiler & shut off valve however x3 of us could not find such a valve? However it does seem like something is not controlling the pressure?
Thank you for replying to my post

The tank in the loft must be a cold water storage tank. Pretty sure it's a pressure relief valve, which means it's a pressurised system with an expansion vessel (for one thing, if it were a vented system with F/E tank in the loft there's no way it would get to 2.5 bar). So there must be an arrangement to fill from mains. Usually 2 valves for safety, often separated by a flexible hose, which should be disconnected at one end after using (though my son has a combi with s valves but a rigid pipe). You'd expect the fill valves to be near the pressure gauge, so you can see what's happening as you fill.

 

[U.P]

Hi,
I agree with what you are saying, it is a pressurized system as there is an expansion vessel (found at top of boiler & we did re pressure with a hand pump) It does point to something like a fill valve not been turned off as the pressure builds so quickly from 0
I will do some 'digging' to try & find where the 'fill valve' is located on this boiler (this does look like the issue) However there is no 'filling loop' on the boiler itself (not a flexi pipe anyway) others with me took some photos of the pipes inside the boiler so will get them & post on on the thread.
There was 2 u shaped pipes going in/out the boiler & 1 had a small grub screw on it so possibly this may be the filler? Bit more digging required i think lol
Thank you for your advice, it's appreciated

 

[fixitflav]

Hi,
I agree with what you are saying, it is a pressurized system as there is an expansion vessel (found at top of boiler & we did re pressure with a hand pump) It does point to something like a fill valve not been turned off as the pressure builds so quickly from 0
I will do some 'digging' to try & find where the 'fill valve' is located on this boiler (this does look like the issue) However there is no 'filling loop' on the boiler itself (not a flexi pipe anyway) others with me took some photos of the pipes inside the boiler so will get them & post on on the thread.
There was 2 u shaped pipes going in/out the boiler & 1 had a small grub screw on it so possibly this may be the filler? Bit more digging required i think lol
Thank you for your advice, it's appreciated

OK, the fill loop is usually near the boiler, but it doesn't have to be, can be anywhere. Good luck!

 

[U.P]

I have just found this video on 'you tube'
MAIN HE 24 BAND B. Inside the boiler casing main he 24kw combi boiler review and full strip down
This is the boiler so may get an idea from this for the filling loop?
Thank you for your advice

 

[Dangee]

Loop letting by,boiler will need draining, pressure vessel will need repressurising, pressure relief valve cartridge will need removing & cleaning. Needs GasSafe engineer.

 

[ianmcd]

you have a filling loop somewhere, try where the HW Cylinder is located , that is a common place

 

[Deleted member 267285]

Looking for something that resembles this: https://www.screwfix.com/p/r24-fill...aqgooSrNksdLJcoQtwV3o75XRM-ELhuxoC1xYQAvD_BwE