Loss of pressure

[spursman]

Hi,

Plumbing novice here so please go easy!

We have a convential potterton boiler, with a megaflo hot water cylinder and cubex expansion vessel.

I have noticed gurgling sounds in the pipework when the boiler starts and saw that the pressure of the system (normally 1bar) was at zero! I have repressurised the system when cold and also bled the radiators, but it still seems to be losing pressure. Also, despite the bleeding of my radiators, there still seems to be air in some of the radiators if I check them a few hours after bleeding, especially the heated towel rails.

Can anyone suggest a likely cause? My biggest concern is a leaking pipe, but I see no evidence of a leak through walls/ceiling. I guess the leak could be on our ground floor level and therefore I wouldn't detect it...

Any advice appreciated!

Thanks

 

[moony]

50 50 - leak or pressure relief valve operating


check for leaks, check relief pipework - if pressure relief valve operating then problems could be due to overheating - or expansion vessel fault or not large enough.

good luck pal

 

[dontknowitall]

It's probably the expansion vessel. However, I'd like someone else to confirm this for me as I'm not 100% sure as to what all the symptoms are.

 

[aggis]

To check if your expansion vessel needs recharging.
With your system cold fill upto 1.25 bar, then turn on your heating [full] & watch the pressure guage, if pressure rises upto 3bar it will drop all of a sudden as the pressure relief will release water.
Get a Engineer to repressurize the exp vessel.

 

[spursman]

Hi,

Thanks for all the advice.

The system when hot does not go above the 1 bar that I repressurised it to.

The 1 bar slowly decreases to 0 over a few hours. I checked the system about 1/2hr ago and it was at zero again...

 

[aggis]

Check safety blow off isn't dripping, if so you've got a leak on the system.