Bosch Worcester Gr8300iw 30 C pressure loss and temperature

[PRoger]

Have just moved home and had a Worcester Bosch Greenstar Life Gr8300iw 30 C installed. It has a thermostat which I had turned down low overnight (but not that low, 18 degrees C) and found the pressure had dropped to something like 0.3 bar the next morning. I topped it up but since then the same thing has kept happening, with the pressure now going low whenever the thermostat is set to less that 27 C.
Is this the usual behaviour when there is a leak in the system, or is there maybe something else going on? Thanks for all replies.

 

[PRoger]

Update: Have just noticed some of the heaters don't seem to be heating up. They are of a very old design (see picture). Are these problems likely to be related?

 

[ChrisB1982]

Hello, no it’s is not normal behaviour, and temperature shouldn’t have much effect on it. If it’s just installed, why not get the installer back?