Trv and lockshield lengths

[PJF220]

We moved into a new property (1967 build) in Septrmber and I've been working my way through the list of jobs.

I've fitted a Tado kit with the Tado trv's to replace the Danfoss ones. The valves were in poor condition and the pins didn't seem to work. With some playing I've got them running, but they are obviously old and I'm not convinced about their reliability. In the Tado app you can see they are going on and off but I'd like to replace them and the lockshields whilst decorating. I went to screwfix and bought new bodies and lockshields, but when I got home, the new ones are smaller! I've attached photos. Question is, can I get a like for like replacement for the trv body and lockshield as they are about 2cm longer. Looking about, most for sale don't state dimensions. Any clues where to buy?

 

[RandomGrinch]

Hi,

I may be very wrong, but the size of that valve (and the 1/2" markings) makes me think of commercial heating valves.
Something like:
https://www.cityplumbing.co.uk/Danfoss-RA-FN15-½-in-Straight-Valve-013G008400/p/966729

Technical drawings and sizes are listed here (at the end of the document):
https://assets.danfoss.com/documents/DOC004786403867/DOC004786403867.pdf
Hopefully one will match!

Otherwise, you could look at getting something like a rigid TRV extension piece, to replace the rad tails?

I'm sure others will have better ideas, good luck

 

[Ihavenojob]

You can use these lockshields
Drayton 07 05 906SX White / Polished Chrome Straight Lockshield 15mm | Lockshield Valves | Screwfix.com
and use these cut down to size on trv and lockshields
Tesla ½" BSP Male Taper x 15mm Compression Rigid TRV Extension Piece 100mm | Radiator Parts & Accessories | Screwfix.com
Tesla ½" BSP Male Taper x 15mm Compression Rigid TRV Extension Piece 60mm | Radiator Parts & Accessories | Screwfix.com

 

[Madrab]

Those are old RA-FN 15 1/2" Straight TRV 1/2" fittings. The way the valves compress onto the pipe is totally different from the way the new 15mm compression valves do. They also use different types of olives. You are lucky though, Danfoss are great for still supplying their old style valves. Just search for the TRV above, you will find them, they won't be exactly the same and threads may be different but the length may be. Give Danfoss a call and they can confirm the dimensions.

The lockshield is a little different and it will be trial and error to get a valve to fit, again Danfoss do longer straight compression lockshields.