OSO Unvented Indirect Hot Water System

[jdjatno6]

The pressure / over heat relief valve is letting by which is creating a steady trickle past the tun dish and through to an external vent. The Pt. Number referred to in the manual is 550803. However, I cannot find any reference to this on a search. The nearest I can find if 550853. My question is this relief valve an updated equivalent. OSO have proven useless having emailed their help line twice and heard nothing. Thanks for any advice out there? Jon

 

[Mbear]

Most likely expansion vessel flat

 

[steadyon]

Some, if not all, the OSO cylinders have an internal air gap for expansion. This may need recharging, although normally this gives only an intermittent discharge from the TPRV of cold water. The OSO guides are available on line, and you may find that the discharge is a symptom of something else wrong, not the cause.

You probably already know, but to work on these systems requires a "G3" qualification.