new valve to old radiator

[I am bonkers]

I have an old cast iron radiator to which I want to fit a thermostatic valve. At present it has a school radiator type valve at one end and no valve at the other, where I intend to fit the TRV. I will of course observe and adjust the flow direction as I re-pipe. The feeds are in 1/2 inch copper but the return connection is via a 90° reducer bend from what I guess is 3/4" at the radiator. I want to disassemble as little as possible as the rad is old. Would a new straight reducer between the rad and the TRV be the answer or would I be better to fit an in-line TRV in the 1/2" feed? There is just about enough space to take the second option but it would look a bit clumsy. If I took the first option are there problems with 3/4" to 22mm compatibility? Just what fitting would I need?

Many thanks

 

[Puddle]

I Know radiator is old but your best option would be to remove the old 3/4 tail and replace with bush (if required) and fit new 1/2 radiator valve fitting into radiator
You will not damage the radiator,the problem is freeing the old 3/4 fitting in radiator,it may require some heat
Or as you can fit thermostatic valves on flow or return now,so maybe you could just fit a 'ln line thermostatic valve' on the return pipework out the top,from the elbow as in comes back down to the floor level

 

[I am bonkers]

You will not damage the radiator,the problem is freeing the old 3/4 fitting in radiator,it may require some heat

Thanks Puddle. Really didn't want to take out the old 3/4" tail if I could possibly avoid it. Is there no possibility of mating a 15mm TRV to it?

 

[Renewable M]

puddle has it in one...... tape up and thread seal the bush and you really are in business in a most spectacular way.

 

[stevetheplumber]

I have an old cast iron radiator to which I want to fit a thermostatic valve. At present it has a school radiator type valve at one end and no valve at the other, where I intend to fit the TRV. I will of course observe and adjust the flow direction as I re-pipe. The feeds are in 1/2 inch copper but the return connection is via a 90° reducer bend from what I guess is 3/4" at the radiator. I want to disassemble as little as possible as the rad is old. Would a new straight reducer between the rad and the TRV be the answer or would I be better to fit an in-line TRV in the 1/2" feed? There is just about enough space to take the second option but it would look a bit clumsy. If I took the first option are there problems with 3/4" to 22mm compatibility? Just what fitting would I need?

Many thanks

i would go with the inline valve in the copper can go low down if you dont want to spoil the look of the old stle rad