Hi there,
I'm far from an expert, but our Ravenheat has the same problem, and always had.
A week or so ago, I found a nice puddle underneath the boiler, and on taking it apart noticed that the pipe right at the top (air overflow valve or something) had a loose connection. I tightened it up, but the water had gone on the circuit board - so I put a fan on it for 12 hours and tried to fire it up. No joy, so put out a call to a friend of a friend who works for British Gas. He gave one of the rubber pipes that go to the fan a little blow and everything worked fine - but he then told me what my problem is with the water pressure.
(long story, sorry, should have warned you).
You have a balloon like device that works as an equaliser to your water pressure. As your water heats up, the balloon deflates to make sure the pressure in the system stays constant. In a system that's working correctly, it shouldn't really go about 2. In a system that doesn't work well, the pressure can go to 3 or higher, which means the system goes into protection mode and kicks out water to relieve the pressure. So check the pressure relief pipe as said above - and if there is water, then it's probably because this balloon like device isn't working properly. What happens when the system cools down is that there is less water there as it's gone to the overflow, so your pressure shows as nearly 0.
The fix is to inflate the balloon manually with a pump - but the problem with my CSI85 is that it's in the daftest possible position, so that very quick job could take hours taking the boiler apart to get to the balloon.
Anyway, sorry for the ramble - but if it's the balloon then you'll see very high pressure (3 or so) and water going out the over-flow. It doesn't necessarily mean you've got a leak.
Dave Smith
January 2009
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