pressure dropping on boiler

paul1

I have to top up my combi boiler every couple of days as the pressure drops. Have not been able to trace any leaks and are now wondering if it could be to do with the copious amounts of steam it produces. I know it should produce some but it seems to go off every couple of hours even when the heating is not switched on. The boiler is only a couple of years old and it has been serviced, but the engineer just said I had a leak from one of the rads which I'm sure I haven't. Any help would be great.

EliteHeat

You have a leak. You might want to consider injecting some leak sealer if you cannot trace it.

Wookey

Where exactly is the steam coming from?

paul1

Steam is coming from the flue outside.I know it should but there is an awful lot of it even when the heating is not on.

Robbo77

You could have 2 seperate problems here. If there is steam coming from the flue, despite the boiler being in an "off period", its safe to assume that the boiler isnt actually off. A possible flow switch or diverter valve fault could cause this.
Your pressure loss isn't necessarily a leak. It may be a faulty expansion vessel or the fact that your boiler is overheating and releasing from the pressure relief pipe. If your boiler is firing up whilst off, it will overheat very quickly.
Depending on the boiler, you should find the pressure relief pipe outside your house, a few feet below your flue. Its a 15mm pipe. If its dripping, the fault is likely to be with the boiler.
Hope this helps.:)

bambibashercol

What make and model combi have you got?
It might be steaming when the heating is off due to having a preheat on the boiler.
When you run the central heating does the pressure gauge rise quickley?
Is there signs of water leaking from the blow off pipe outside?