Pressure guage dropping on Potterton performa 28

[john roche]

I have a Potterton performa 28 combi boiler. Since the central heating has engaged this year the pressure guage has been dropping every 24 hours to below 1 bar , zero at times. I have refilled using the top up loop (it only takes about two seconds) added fernox leak sealer to the system and bled all the rads, but pressure drops again over next 24 hours. I have noticed that when the pressure shows low there is no low pressure warning light active and hot water and heating still work. Question is, do pressure guages fail in this way? is there a way to check or should I just replace it and see
Thanks

 

[tipintim]

First things to check are:
1. Any rad valves leaking on tails
2. Automatic air release valve leaking on boiler
3. Check expansion vessel is not full of water ( this would be my guess or no 4 )
4. Presure release valve not dripping out to garden ( put a bag on it for an hour or so to see if it is passing )
Cant see it being anything to do with the presure gauge, but u never no

Let us know how you get on. :yesnod:

 

[john roche]

Thanks tipintim,
I have checked all the valves and any pipes available and can detect no seepage.
On a previous refill, once the central heating came on the pressure rose above 2 bar and I could see the PR valve pipe dripping , so I have assumed that the PR valve is working ( I will however recheckj)
How do I check the expansion vessel, is it just a matter of putting a pressure guage on it ?

 

[mfgs]

Sounds like you need to get a Gas Safe registered engineer to take a look at it.