Update.
Boiler SV now 100C.
Not being happy with the holed, cracked and perished seal on the OPV valve, I thought that I would do something about it. As far as i’m aware, these seals aren’t sold by the spares suppliers, so searching ebay for suitable rubber sheet to make a new seal, I came across a listing for five ½” seals for an antique brass tap. These looked promising as they were about the right diameter, had no central hole and would presumably be heat resistant and drinking water safe. They turned out to be slightly too large to go in the seal holder, a bit thicker than the standard seal and also felt a bit squishier. The old seal disintegrated when I removed it so I am now committed. To get the new seal diameter right I cut a piece of tube from an old tent pole, this had the right 11mm internal diameter, cut a taper on one end on the lathe to form a cutting edge. Pressing the seal against the tube in a vice cut the seal to the right diameter. Not the neatest cut, it was a first attempt, but it’s the central area that seals. Assembled the lot and adjusted the OPV to 10 bar showing on the on board gauge when hot. It holds 10 bar, I have no idea if it is durable, affected by long term or if there will be any unforseen problems, but there is only one way to find out…
I also replaced the two O rings on the steam valve stem while I was in there, I found some of the correct viton 6.07 × 1.78mm size in my spares box.
