I am trying to add thermostatic radiator valves to a system that was installed 20-30 years ago. The existing pipework to the radiators is microbore, but seems to be a size intermediate between 8mm and 10mm. My guess is that it's an imperial size of microbore (3/8" perhaps?)
Any thoughts about what it may be and how to adapt to 8 or 10mm fittings?
Cheers,
Mike