Gas boilers spewing out water BAR at 3

jack2009

Registered User
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Some help required please.

At the moment the BAR is at 3 and the boiler is spewing out water non stop. I can get this to stop if I let the hot water run but shortly after turning the water off the pressure builds up again.

I am not sure if it is the cold and that something has been damaged or if I messed up the system when bleeding rads.

I think I may have messed up the system! I first bled the rad in the attic and turned off the water but forgot to turn it back on. Then noticed another rad not working so bled that. I then noticed that the BAR was wrong and did a walk around the house and remembered that I did not turn the water back on. I then turned the water back on and could hear air escaping from the valve at the hot water tank. This stopped after a few seconds.

Now there is a slight noise near the valve on the water supply and it comes on goes as I turn the water supply on/off.

Any help would be appreciated.
 
Looks like you have overpressurised the heating system. Make sure that the valve feeding the system is disconnected. The standing pressure in the system should be set at between 1/1.5bar when the boiler is off. This pressure will rise to approx. 2/2.5 when the system is on and heating.
 
Looks like you have overpressurised the heating system. Make sure that the valve feeding the system is disconnected. The standing pressure in the system should be set at between 1/1.5bar when the boiler is off. This pressure will rise to approx. 2/2.5 when the system is on and heating.

Thanks for the post, what do after I disconnect the valve?
 
...how are you refilling the system ? I mean, how are you getting the pressure in the system so high ? AFAIK, mains can't get it that high, gravity tank def won't: so, are you using a pump or something ?

Have you isolated the boiler or something, so that it's the boiler that's over-pressure, and not the system ??
 
...how are you refilling the system ? I mean, how are you getting the pressure in the system so high ? AFAIK, mains can't get it that high, gravity tank def won't: so, are you using a pump or something ?

Have you isolated the boiler or something, so that it's the boiler that's over-pressure, and not the system ??

I dont know! I have not done anything to the boiler or at least I have not touched it!

As for refilling the system, we have a pump in the house but as far as I know it is only for the water in the taps. I think this because the pump is not "going off" even though the water is coming out of the system.
 
Check the pressure when the system is cold it should be about 1.5 bar.
If it is more than this release some water if it is less add more water. If the pressure then reaches 3 bar when reheated you have a faulty expansion vessel. This should have an air pressure of 10 psi when all pressure is released from the heating system. If the pressure is less than 10 psi air should be added using a car footpump. If water escapes from the valve when testing the expansion vessel, then the diaphram is damaged and a new unit is required.
 
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