Thread size on radiator inlet and valve

[Foston]

I recently purchased a new towel rail but could not fit the two valves [Thermostatic and on/off] as the threads on the valve and radiator did not match up. The valves were purchased separately from the radiator but I did not see this as an issue. The on-line supplying company is sending a replacemnt radiator and hopefully the problem will not arise this time around. However, in considering whether or not to purchase a tap and die set I realised that I did not know the size or thread type in a standard radiator. Can anyone help please. Is it 15mm or 1/2 inch and is the thread BSP?

Many thanks

 

[armourer]

Standard is 1/2 inch bsp but on older radiators it can be 3/4 in BSP.

 

[brybhoy]

Forget the tap & die set!! Now just wait for the new towel rail. As the above post states should be 1/2" on the new towel rail but it appears you have a 3/4" tail for the valves on the existing pipework...

 

[Foston]

Many thanks.

 

[stevetheplumber]

ive got a half inch and three quarter tap in my box of drills but cant remember the last time i used them threads are normally good nowdays but often needed then on cast boilers