when on water heating only the pressure reverts back to 1.2 bar instead of the 1.0 bar.
when on both heating and water the pressure rises to 2.7 bar (flashing) and when switched off reverts back to 1.3 bar and not 1.0 bar which i understand is the ideal reading.
what do i do to correct those readings?

Robert Armstrong, March 2007

good answer ger walsh, but also check that the pressure vessel isnt faulty and also theres the right pressure in it. pressure reading can be found on vessel normally.to check pressure a tyre gauge or good pump.if to low pump it up to correct pressure for vessel.

simon, March 2007

My 30SI had a similar problem only it didn't revert back to normal pressure when switched off. What was happening was the stopcock on the fill pipe (seperately located in the hot press) was faulty and was allowing too much water into the system. I replaced this valve and there is a drain valve under the boiler, to which you can attach a hose/tube and open the knurled knob letting water out until the pressure drops back. Although 1 Bar is the ideal setting, water when heated will cause the pressure to rise slightly and 1.2 or 1.3 Bar is not really a problem. I am open to correction by any Engineers out there. What you are seeing with the pressure falling back to 1.3 seems a little different. Hope this helps in some way.

Ger Walsh, March 2007