combi boiler pressure regulation

[Walthamstow-J]

Dear DIY-noters,

When I go away for 2 weeks I invariably come back to my 2 year old Baxi Duotec 28HE flashing E19 (pressure too low) - even if I've had it come on every day. I fill it - just until it starts up again - and all is well....

Next morning - pressure gauge is showing in the high 2's - last time in the red so that I had to take the front off & let some pressure off.

I don't really think I should be doing this so often. I'd really appreciate any advice (other than that I bought the wrong boiler - it's too late for that). Is there anything to be done to stop it yoyoing like this?

thanks very much in advance,
J.

 

[ianniann]

You're right, it shouldn't need fiddling with this much. The pressure should maintain at working levels for months if not years, and it shouldn't rise to red levels from the right pressure.

Clearly you have some sort of leak, so look for water You should be able to spot it if the pressure goes down that fast but it might be under the floors or possible a pressure relief valve is letting the water out.

The rising pressure is often caused by a failed or empty expansion tank, but sometimes the filling loop lets water through slowly so make absolutely sure it is shut off. Disconnect completely if necessary to check. Many newer boilers have a "key" that temporarily connects the inlet so water cannot possibly pass when the key is removed.

 

[Walthamstow-J]

ahh - so that's what all the puddles are about then?

Thanks so much for your reply. I feared as much. It must be a really tiny leak as this all only happens when it's out of use for more than a few days. Would a hairline crack only open up when a pipe is cold, but not when the heating is on? That's the only way it logically makes sense. I'll have to do some floorboard lifting - there's nothing obvious.

The last time I used the PRV I struggled to get it to close - and had a running overflow pipe for a bit until I fiddled with it sufficiently. The overflow isn't dripping any more - but may indicate a weakness in the PRV - ?

As to the rising pressure - I'll check as you say. No key, just a tap that turns 90`. I was advised, I must admit, to take the filling loop off. Bit chicken & egg - I need it easily available because of this problem!

Sorry to ramble - thanks again for the help.