I need to replace the heads on a couple of very ancient TRVs, which are MMA branded and have M28 x 1.5 threads. Does anyone happen to know whether any of the sheddy no-name valves happen to have this thread? Most valves seem to be M30 x 1.5 these days, and adapters cost more than cheap valves.
Pegler Terrier i30s seem to come with an adapter, but £30 each seems a bit OTT for background heating in a couple of spare bedrooms.
ICBA at the moment to change the whole valve - they have a union fitting on the rad tail, which hasn't been disturbed these 30 years, and probably would prefer not to be disturbed now, and a sleeve nut on the copper. Moving house is not an option yet.