Old Rads, replace valves with TRVs, sizes different
Discussion
Hello All,
I need to do some maintenance on the rads of our central heating.
I need to replace 2 rads, together with new TRVs and lockshields. Pipework may have to be altered slightly as the old rads seem to follow imperial widths (i'll get something close and see if I can make it work with tail extension pieces if I can).
The remaining 5 rads, the valves look pretty knackered been in place for years. The rads are old but not much sign of external corrosion. Although, maybe different if I have to remove the old tails....... That lead to my question and a bit of confusion.
The old wheel head and lockshield valves on all the rads appear to be 15mm x 1/2 fitting. Into a 1/2 threaded tail with nut to connect to the 1/2 valve.
Almost all the new TRVs and most of the lockshields are 15mm x 15mm. And the tail set up seems to be threaded at one end into the radiator thread and then a 15mm pipe and olive connection to the valve.
This has 2 concerns for me:
1. All of the new 15mm x 15mm valves (TRVs and Lockshields) seem to be about 58-60 mm length from centre of valve to end of tail thread.
2. Looking at where the thread is likely to end in the radiator in mine it looks like 50-52mm but I am inferring. Bending pipework up to 10mm each side won't work as it'll be out of square with rad entry. Creating a bit of a mare just to replace valves.
Do the "new" the 15mm x 15mm pipe and olive tail allow some movement so you could reduce the 60mm slightly (8mm to 10mm) to match up to the length of the old valves without altering pipework?
Why did they change? Doesn't it make it a lot harder to remove rads by closing just valves because the 15mm pipe of the tail extends into the valve body? So you would need to fully drain down system and remove at least one valve just to remove a rad?
Can't seem to really find many 15mm x 1/2" TRVs. The one I did find was a Myson decorative unit was like £35 plus vat just for the TRV and the length to end of thread said 58mm anyway! So that is not an option.
Advice appreciated. Please tell me if I am off track.
I need to do some maintenance on the rads of our central heating.
I need to replace 2 rads, together with new TRVs and lockshields. Pipework may have to be altered slightly as the old rads seem to follow imperial widths (i'll get something close and see if I can make it work with tail extension pieces if I can).
The remaining 5 rads, the valves look pretty knackered been in place for years. The rads are old but not much sign of external corrosion. Although, maybe different if I have to remove the old tails....... That lead to my question and a bit of confusion.
The old wheel head and lockshield valves on all the rads appear to be 15mm x 1/2 fitting. Into a 1/2 threaded tail with nut to connect to the 1/2 valve.
Almost all the new TRVs and most of the lockshields are 15mm x 15mm. And the tail set up seems to be threaded at one end into the radiator thread and then a 15mm pipe and olive connection to the valve.
This has 2 concerns for me:
1. All of the new 15mm x 15mm valves (TRVs and Lockshields) seem to be about 58-60 mm length from centre of valve to end of tail thread.
2. Looking at where the thread is likely to end in the radiator in mine it looks like 50-52mm but I am inferring. Bending pipework up to 10mm each side won't work as it'll be out of square with rad entry. Creating a bit of a mare just to replace valves.
Do the "new" the 15mm x 15mm pipe and olive tail allow some movement so you could reduce the 60mm slightly (8mm to 10mm) to match up to the length of the old valves without altering pipework?
Why did they change? Doesn't it make it a lot harder to remove rads by closing just valves because the 15mm pipe of the tail extends into the valve body? So you would need to fully drain down system and remove at least one valve just to remove a rad?
Can't seem to really find many 15mm x 1/2" TRVs. The one I did find was a Myson decorative unit was like £35 plus vat just for the TRV and the length to end of thread said 58mm anyway! So that is not an option.
Advice appreciated. Please tell me if I am off track.
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