ariston gas boiler

[jessie.2.u]

Hi i have an Ariston wall hung boiler. I fill system to 1.5 bar. During course of day gauge shows zero ?.Some times gauge shows 1 bar ---- and you check 15 minutes later ---shows 1.5 bar. in morning have to fill system
have checked around --no leaks found.Anyone out there got any ideas
Boiler has 3 buttons on front left hand side. +temp knob to right,+ pressure gauge to right
1=on /off button.
2=radiator symbol.
3=reset.
There is a big knob beside these to right, dial from 1-5 then echo-- max temp( there is a small light blur circle on this knob).
The pressure gauge is to the right of temp knob. ANYONE OUT THERE THAT CAN HELP?

[absolheat]

Have you checked there is no water coming out of the discharge pipe? Thats the copper pipe that bends back to the wall outside the house. A good way to check this is to put a plastic bag on the pipe; fastened with a rubber band. If its been leeking for any length of time there could be a stain on the wall outside.

[jessie.2.u]

Hi have checked pipe is ok water only come out if i allow 3bar pressure. if i drop back to normal 1.5- 2bar all ok

[absolheat]

Hi have checked pipe is ok water only come out if i allow 3bar pressure. if i drop back to normal 1.5- 2bar all ok

Sorry your missing my point. Does the water pressure go over 3 bar when the heating is on? Even if it was only 1.5 bar before the heating was on.

[jessie.2.u]

Hi if i fill to 3 bar----everything is ok. If i leave water from inlet on when it reaches over 3 bar valve activates and discharges water. I close inlet and water stops---gauge shows 3 bar. --- i can run boiler. during course of evening pressure drops.I have checked outside and there is no discharge from overflow pipe during period of heating. Could the system have an air lock. Having checked some rads ---- top is hot ---bottom look warm. I have vented these rads and water comes out immediately

[jessie.2.u]

Pressure wheni start is 1.5 some times it will go up to maybe 1.7.and when you check boiler later it has dropped right down----0.5 or lower.