Megaflow expansion vessel

[rotadays]

Hello everyone,
Bit of advice would be appreciated.
My Expansion vessel has recently been looked at by B Gas, the Engineer re inflated to 0.7bar via the Schrader valve and the water pressure was set at 1.2 bar.
This is because the water pressure kept on falling on the pressure gauge and I was continually having to re pressurise.
My question is what is an acceptable fall in pressure and over what time scale?
I am on a years contract with B Gas which is due to finish in the next week, I don't want to call them out again if it is not necessary.
The pressure has fallen from 1.2 bar to 0.7 bar in around 7 weeks.
Thanks in advance.

 

[flameport]

The pressure has fallen from 1.2 bar to 0.7 bar in around 7 weeks.

There is a leak somewhere.

what is an acceptable fall in pressure and over what time scale?

Next to nothing over many months or a year.

 

[rotadays]

Thanks for the reply.
Could there be a hole in the rubber diaphragm, as there is no obvious leak from any of the pipework or radiators.

 

[flameport]

Could there be a hole in the rubber diaphragm

Not impossible, but if there was you would be able to get water out of the air valve on the EV so this would be obvious.