Erratic pressure on Vokera combi boiler

[SeaDoug]

On a regular check, I noticed the pressure was low on the CH loop - so I topped it up (to about 1.3bar). The boiler was not running at this point.

Later, while it was running, I noticed the pressure had climbed to about 2.7 - approaching the danger point... So, I drained some water from the system.

The next day, the boiler had not ignited at it's appointed time, citing low-pressure as the reason for not doing so.. I topped the system up and checked back later - again, the pressure is up at nearly 2.5. I left it this time and later, when it had been off overnight, the pressure was again too low to ignite boiler.

Is there any chance I've inadvertantly bust some internal valve or something? Just don't get it... Seems that, so long as it's running, the pressure remains fairly constant - though too high. When it shuts off, the pressure is leaking away somewhere. Thought maybe air in system somewhere - thinking it would expand when hot and increase pressure.. but dont see why all pressure lost when boiler shuts down - I can find no water leaks anywhere..

Any hints, advice or just general comments will be very much appreciated!

 

[picasso]

Have a look at the FAQ,s on expansion vessels.

 

[dangas123]

I would recommend you get an engineer to service your boiler. As part of the service he will re-pressurise your expansion vessel. Lack of charge in the vessel is the cause of your problem.