Ravensheat Boiler pressure dropping rapidly


11 Jun 2004
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United Kingdom
My Ravensheat RSF 820 / 20 combi boiler is losing pressure very quickly.

It says on my boiler the pressure should be maintained at 1.

When the boiler is running the pressure stays but as soon as it turns off the pressure just goes down rapidly and straight to zero and the pilot also goes out.

Please can advise what the problem is and if anyone else had a similar problem with their boiler.

Thanks in advance

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You could be losing pressure at the pressure relief valve (may need reseating / replacing ) or have a leak somewhere in your system.
Check all joints. ;)
Thanks Bahco,

Where would the pressure relief valve be on the boiler,

Is it something easy to do or an engineers task.

Sounds like to me that if it has an expansion vessel fitted then this might be the problem, does your pressure gauge go very high when the boiler is running?. if it has one fitted it will have a tyre valve fitted to it, just do a quick check with a small screw driver on the valve and see if water or air comes out. If water comes out then your expansion vessel is u/s.

Flack :(
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When the boiler is running the pressure does not go very high, between 1 and 2.
As soon as it is turned off it goes to zero within 5 minutes and soon after the pilot goes off too.

Quote 'If water comes out then your expansion vessel is u/s' - what does u/s mean?

Sounds like a similar problem to my boiler.
I located a small valve on top of the boiler similar to a dustcap and it was loose.
I retightened it but the pressure hasnt increased since, is there a way of re-pressurizing the system or should it happen naturally?
Yes, I found the cap too on the top of the boiler, more like a cap on your car tyre.

The only reason I found this was cos it started making a hissing noise from the top, the cap had completely come off.
I had this screwed back on but the pressure is still dropping.

I have to manually increase the pressure.

If you just tightened the dustcap on the automatic air vent - you have stopped it from working.

If you tightened something else - well, I have absolutely no idea what will happen next!

If you have no manual for the boiler then I strongly suggest that you should get a professional to fix it. What you are doing is potentially dangerous, probably illegal and (after several days) clearly not fixing your boiler!

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