Hi I have a Protherm 80E which has an odd fault in that the if pressure is set to say 1.5 bar all works exactly as it should. However the pressure gradually drops to a level low enough to cause the F0 fault (this can take 3 or 4 days).

I have replaced the 3.0 Bar safety valve and can find no leaks in either the DHW or CH piping rads etc.

Can anyone out there help me as to what the fault could be please?

Bryce, December 2006

If the vessel is fine, jump in the car and take a trip down your local plumb merchants; buy yourself a tube (Upto 10 rads) of "Central Heating Leak Sealer"... Might solve your problem without tracing pipes.

As it's a sealed system, save yourself some time and get yourself a rad injection kit with it as well... Your plumbing merchant will be able to give you some advice on how to inject the liquid into your system.

GasAid.co.uk, December 2006

Thanks for your help seems like a fairly big job to trace all the pipes as will need to lift carpets etc..ho...hum...

bryce, December 2006

if vessel is found to be faulty they have to be replaced.

hi-spec, December 2006

you can check the expansion vessel pressure. on the vessel is a valve same as a car tyre , get a tyre pressure gauge and check pressure it should be about 1 bar. also push the valve to see if it releases any water. if the pressure is low you use a car foot pump to get back up to 1 bar, but the system must be empty of water. most cases if the vessel is faulty the pressure rises quite high the warmer the system gets.

hi-spec plumbing, December 2006

Just another quick thing incase I do not find any leaks how do I fix an expansion vessel fault please?

bryce, December 2006

Thanks I will need to do some serious work to find it if that is the case.
It is in a flat and I have had no complaints from the flat below, how much water are we talking about in the system?

bryce, December 2006

i would say u have a leak some where under floorboards etc. it doesn't seem bad enough to be expanssion vessel fault.

hi-spec plumbing, December 2006

It rises a bit up to 2.0 when hot

bryce, December 2006

if the boiler set to 1.5 does it rise when heating on. or stay at 1.5

hi-spec plumbing, December 2006