Ferroli Optima 901 Pressure Problem - Help Please !!!

[johnnywishbone1]

Hi,

I have a problem with my Combi boiler whereby the pressure rises to about 3 bar when the central heating has warmed up but if I switch off, the pressure drops to Zero!!! If I leave the heating on it works perfectly although the pressure is high obviously. When the pressure drops I have to refill using the filling loop. I top up to just over 1 bar but again, when the heating kicks in and warms up it rises to 3 bar. Any help would be greatly appreciated.

Cheers

 

[hect]

Possibly exp vessel - is your PRV passing?

 

[jackthom]

It's likely the expansion vessel causing problems.

Lots of info in FAQ31 //www.diynot.com/forums/viewtopic.php?p=775553#775553

 

[johnnywishbone1]

Thanks gents, I'll give it a go this weekend

 

[johnnywishbone1]

Right then, so I have just changed the expansion vessel after draining down the system as per the FAQ instructions. I didn't actually have any water coming out of the schrader valve of the original which would indicate a defect but I decided to change the tank anyway as I already had the spare one ready to go. It was £42 from plumb centre so not the end of the world. After refilling the system and bleeding all the rads I noticed something strange. On the bottom cover I saw dry green gunk !!! When I looked above it I could see it had been coming from the automatic air vent attached to the air seperator. It's a knurled thumb screw which is quite difficult to get at. Firstly I tightened it down but then no air could escape when the central heating was running and so I opened a little and could hear air escaping and could see air bubbling through the green stuff for about 30 seconds and then stop. I assume this is to relieve the system of trapped air ? Any ideas anyone ??

Also, any ideas how best to replace the inhibitor in the central heating ?

Cheers.