Boiler pressure low - Main combi Eco

[Squeekster]

Hi chaps my Main combi eco boiler keeps losing pressure,can't see any leaks but it does say check auto air vent i think this is on the top of the boiler but how do i check if it's working?

Suzzane there is usually a tap on a pipe below the boiler you just turn it and you will hear water enter the system and you should see the pressure clock go up, although the Worcester/Bosch boilers have an extremely complicated system (for no good reason) to re-pressure.

 

[terryplumb]

Squeekster ,you would be better starting your own thread ,to get input ,as this one is a different thing altogether and months old. When you do give the full model name /number of the boiler. The more info you give ,the better .regards Terry


Done - Mod

 

[terryplumb]

The automatic air vent is located on the top of the pump ,and slightly left. If that's letting water pass you should see evidence , at the bottom of the boiler or floor. How often do you need to top up pressure ? And when c/ heating is on for an hour or more is the pressure gauge reading over 3 bar by any chance ?

 

[Squeekster]

Thanks mod for giving it it's own thread.

Terry, I can see no evidence anywhere that there maybe a leak by the boiler or radiators.

The boiler deosn't seem to reading just over 3 bar when the central heating is on it usually gets that low it kicks out.

 

[terryplumb]

In order to establish if you are losing pressure within the boiler or externally you can turn off the isolators on the central heating flow and return pipes below the boiler. First make sure pressure is around 1.25 bar. Turn off electric supply to boiler.then leave it overnight. Next morning if pressure has dropped the fault is in the boiler.if not its on pipework / radiators etc. I asked how often you top up pressure, but you did not reply .if you are topping up once a week the above is not going to reveal much. Going from your boiler to outside or drainage there are two pipes.one is copper and this is the pressure relief pipe ,locate its terminal end and see if there is any sign of water having been expelled from it. If you do the safety valve ( PRV ) is allowing water out ,causes pressure drop .it should only do that if your system pressure is over 3 bar ( hence me asking ).the other pipe is the condensate pipe which goes to drainage ,either internally or externally. When boiler is running a small amount runs out this ,however when boiler is not running and hasn't for a bit ,nothing should come out ,if it does you have a fault inside the boiler that will be a fairly expensive repair.

 

[Squeekster]

In order to establish if you are losing pressure within the boiler or externally you can turn off the isolators on the central heating flow and return pipes below the boiler. First make sure pressure is around 1.25 bar. Turn off electric supply to boiler.then leave it overnight. Next morning if pressure has dropped the fault is in the boiler.if not its on pipework / radiators etc. I asked how often you top up pressure, but you did not reply .if you are topping up once a week the above is not going to reveal much. Going from your boiler to outside or drainage there are two pipes.one is copper and this is the pressure relief pipe ,locate its terminal end and see if there is any sign of water having been expelled from it. If you do the safety valve ( PRV ) is allowing water out ,causes pressure drop .it should only do that if your system pressure is over 3 bar ( hence me asking ).the other pipe is the condensate pipe which goes to drainage ,either internally or externally. When boiler is running a small amount runs out this ,however when boiler is not running and hasn't for a bit ,nothing should come out ,if it does you have a fault inside the boiler that will be a fairly expensive repair.

Sorry Terry it varies sometimes i can top it up every day then other times it's a few days, I have looked at the copper pipe out side of the property and can't see any evidence of water on the wall where the out let is, there is also a plastic pipe that runs into the external drain so its difficult to know if water is coming out that way.

 

[terryplumb]

Think you need an engineer to visit to diagnose for you , hopefully sort it before Xmas .

 

[Squeekster]

Think you need an engineer to visit to diagnose for you , hopefully sort it before Xmas .

I think you might be right mate.

 

[Squeekster]

Think you need an engineer to visit to diagnose for you , hopefully sort it before Xmas .

Hi mate there is in fact water coming from the outside pipe so i really think this is where I'm losing the pressure, whats the name of the valve on that outlet?

 

[terryplumb]

Hi , I assume you are not referring to the plastic condensate pipe ,but the copper one. The ' pressure relief valve " ( PRV for short ) is within the boiler ,and is connected to the copper pipe that shows itself outside . this valve should only allow water out to relieve pressure ,and operates around 3 bar. So you need to establish why its lifting. It may be faulty ,or it may be doing what its supposed to .regards terry.

 

[Squeekster]

Hi , I assume you are not referring to the plastic condensate pipe ,but the copper one. The ' pressure relief valve " ( PRV for short ) is within the boiler ,and is connected to the copper pipe that shows itself outside . this valve should only allow water out to relieve pressure ,and operates around 3 bar. So you need to establish why its lifting. It may be faulty ,or it may be doing what its supposed to .regards terry.

Thanks Terry i have done a few things suggested by my friend who was a plumber who offered to help only if all else failed and as at least 6 or 7 plumbers have let me down i had a go myself with his instruction. I opened the PRV and pressurized it and although when the heating is running the pressure remains in the green section i still do have a tiny drip out side id the the PRV valve fault?

 

[terryplumb]

Well its been a few weeks since your original post ,and I have no idea what's transpired in between then and now ,BUT you stated then that no water was coming out the prv pipework. And now it is . if the prv has been manually opened ,it may well not fully close. I can't think why your friend has told you to open the prv ,as the problem you originally posted was relating to pressure loss ??? Maybe he suspected it was not fully closing originally ,and by manually opening it ,it may clear through any trapped impurities ,and then close fully. But if ,originally ,there was no sign of water coming from the prv pipework ,as you advised , then opening the prv manually is pointless ,and indeed may well cause it to not fully close. Bear in mind the prv is a safety valve ,it should only open if something is wrong I.e excessive pressure. Under normal circumstances it should stay closed , for years . if your system pressure stays within the green section ( less than 2.5 bar) ,then the valve should not allow water out the system.

 

[Squeekster]

Well its been a few weeks since your original post ,and I have no idea what's transpired in between then and now ,BUT you stated then that no water was coming out the prv pipework. And now it is . if the prv has been manually opened ,it may well not fully close. I can't think why your friend has told you to open the prv ,as the problem you originally posted was relating to pressure loss ??? Maybe he suspected it was not fully closing originally ,and by manually opening it ,it may clear through any trapped impurities ,and then close fully. But if ,originally ,there was no sign of water coming from the prv pipework ,as you advised , then opening the prv manually is pointless ,and indeed may well cause it to not fully close. Bear in mind the prv is a safety valve ,it should only open if something is wrong I.e excessive pressure. Under normal circumstances it should stay closed , for years . if your system pressure stays within the green section ( less than 2.5 bar) ,then the valve should not allow water out the system.

Please excuse my ignorance Terry but when i was looking before It was usually after work when the light wasn't the best and as i'm now off work and seen it in the cold light of day there is clear evidence and to back this up i did do the little plastic bag trick (this was over a week ago as i have still been trying to get a plumber out to me) so this could of been going on for a while.

 

[terryplumb]

Aha ,that explains it. So its been letting by all the time. Monitor your pressure gauge , cold should be around 1 bar ,when CH heats up should go up a bit ,but never really over 2.5 bar ( much less than that if you only have a small system with a half a dozen rads). If it stays within that and you still get water out the prv pipework ,change the prv. If it goes above you have an underlaying problem with the expansion vessel.

 

[Squeekster]

Aha ,that explains it. So its been letting by all the time. Monitor your pressure gauge , cold should be around 1 bar ,when CH heats up should go up a bit ,but never really over 2.5 bar ( much less than that if you only have a small system with a half a dozen rads). If it stays within that and you still get water out the prv pipework ,change the prv. If it goes above you have an underlaying problem with the expansion vessel.

Thanks Terry you've been a great help just one more thing is this the part i need?
BAXI 248056 SAFETY VALVE 3 BAR, my boiler is a Main combination 30 eco?