Which TRV?

I use Drayton TRV4, because over the years, I've never had one fail. They aren't cheap, although I have got a good price buying 10 or more, when I haven't been in a hurry and can keep an eye out for a good offer.

About 10 years ago. We had nothing but that classic Drayton TRV4 on all our radiators. They all failed. Turns out the Fernox MB-1 inhibitor we had in the system reacts with the valve seal to cause malfunction.

Fernox hinted at this to me without committing themselves and eventually someone from Drayton came round and changed the valves for a different model. I forget which.

Interesting - who paid for that?

I always use Sentinel X100. I just took a new TRV4 out of its box to look at, and the valve looks to be a rubber washer closing onto a chromed brass seat.

NT

Th work was done free of charge but only after many phone calls during which I learned more about central heating than I ever wanted to know.

Drayton and Fernox had a reputation back then for high quality products, so incompatibility was a surprise all round. The technical people at Fernox told me about this after speakign to them many times.

It's not that I have much to do with central heating and normally wouldn't have heard of brands like Fernox and Drayton but this got so protracted that the saga stuck in my memory.