Hot water mains causing Pressure to rise.

[kirkyboy1995]

Hi all, recently noticed boiler pressure (Baxi 105e) was at 0. Topped it up to the boilers recommended 0.5 bar cold , still dropping. Went around the house and found two leaks on radiators, one at a blanking plug, one where water feeds in/out of radiator. resolved them both, great.

It seemed boiler pressure was still dropping gradually. I was recommended bleeding all radiators, I did and no air expelled, except from about a milliseconds worth of noise from a downstairs radiator.

It seemed that the boiler pressure wasn't dropping anymore, as I've been continuously checking. However today when my girlfriend run the hot tap in the bathroom as she was getting ready I noticed the gauge shot up from about 0.4 bar (i'd left it there to see how long it would take to leak back down to 0) to about 1.2 bar. The boiler was making a rattling in the bottom right also. - Soon as the tap is shut off, the boiler pressure would drop to bellow 1 bar and then fall as the water cooled to around the 0.5 bar mark.

Would I be correct in saying that a faulty heat exchange could be the cause of the increase in pressure and also leak in pressure? There appears to be no external signs of leakage.

Thank you for any help in advance
kirk

 

[huddster]

Sounds more like a flats expansion vessel, the expansion vessel absorbs the increase in volume of water as it heats, if there is no air in the vessel the pressure will increase and is most likely the cause of the leaks on the system.
A pin holed plate heat exchanger would give a constant rise in pressure.
You will need an engineer out to put right, leave it too long and you will end up with more issues.

 

[Simon F]

the instant pressure change was due to the pump turning on.

 

[kirkyboy1995]

The pressure gauge is for the Heating system only - So if I have turned on the hot-tap - Wouldn't that mean water from that part of the boiler is transferring either water or air into the heating system?

 

[huddster]

No mate, your boiler heats water which is either pump around your radiators to heat your home or internally in the boiler where the heat is transferred through the plate heat exchanger to the clean water which goes to your hot taps.

 

[Allgoode]

Get a GSR engineer out to sort for you, sounds like the boiler needs a good service as well to give you a baseline condition. Worth spending a few quid to get this problem sorted & give you some peace of mind.

 

[Gareth Harris]

in my limited experience i would suggest an issue with the expansion vessel... certainly check the air valve on that for a starter, see if you get water out of it

 

[Deleted member 84951]

Well you said it yourself, 'in your limited experience',
Perhaps in this instance, the gsr's should really take this issue on.
Appreciate your help tho Gareth, totally.
Sometimes it's better just to observe and increase your knowledge, than it is to offer it.

 

[moonlight]

Please employ a GSR person to look at your boiler. Do not attempt to repair yourself.