Very old & knackered TRV needs replacing.

Max Tout · Aug 23, 2014

I need to replace a failed TRV on a radiator that has 8mm microbore copper piping. The radiator/TRV/piping are all original and have been in place for approx 30 years.

I know that I’ll need a 15mm-8mm reducer as all modern TRV’s have 15mm connectors (is that right?).

However I’m unsure what type of 15mm-8mm reducer to use in conjunction with the new TRV; there seems to be 2 types...............

One type has an 8mm compression fitting with a 15mm tail; the whole thing appears to be about 75mm in legth. The other type calls itself , quote “TOWEL RAIL RADIATOR VALVE INTERNAL INSET REDUCER MICROBORE PIPE 8mm”

Which will I need???

I’ve changed one of these TRVs about 10 years ago but that was in conjunction with moving the radiator to another wall and adding new pipework, which was increased to 10mm.

I also recall having to remove the internal connection from the radiator itself so that it would accommodate the new TRV fitting/size etc.

It’s so long ago I’m a little uncertain of what details the job entails. Anyone care to enlighten me please.

Also, are these TRVs any good;

“Plumb-Pak Thermostatic Radiator Valve 15mm - Elegance Model”
That’s the description on Amazon; £7.88 each. Sorry I can’t post a link as new members aren’t allowed to.

All replies gratefully received. Thank you in advance.

lame plumber · Aug 23, 2014

the price will let you know how good they are and they are really cheap. easiest way is to use 8mm/15mm ef reducer and a normal 15mm trv by honeywell or the like.