Saunier Duval F24 Pressure Fluctuating.

[coldfeet01]

Hi.
Have Saunier F24.
With hot water always used to light up for a few seconds then off again so was hard to get a good HW temp but CH great.
Few months back took ground floor radiators off for building work. Boiler went to 0.0bar and stopped red light. Finished work replaced rads, refilled system with blue knob, bled all rads left pressure at 1.1 bar. Fine for few months but HW problem returned.
Last night came home to Stop/Redlight 0.3bar. Checked boiler and rads for leaks and refilled to 1.1. Switched CH on. 5 mins later pressure reading 1.9 and climbing. Got scared at 2.2 so bled rad till back to 1.2. Everything worked. Woke up to ice and 0.5bar and boiler off again.
If only answer is leak then have to rip up floorboards so really hoping it is something else.
Notice normal advice with Saunier involves hammer and skip, any other suggestions gratfully received.

 

[bellairaphon]

fill the boiler n put ya heating on. n watch the pressure gauge. see what its goin to n go check outside if it rises above 3 bar, see if the '' blow off '' is dripping if it is give ya expansion vessel a pump up make sure u open the prv vavle same time your pumping up, check for water when u press the valve in if water comes out ull need a new expansion vessel