I have a heating system comprised of skirting radiators that form part of a loop from the boiler, round the house and back. Some rooms get warmer than others despite closing off the skirting radiator heat vent. They are designed to house the finned heating pipe and a return pipe, the latter position being empty. I have been thinking putting a pipe in and divert the flow to bypass the finned pipe. But that would be a manual diverter valve which would swtich the radiator on or off. Is there such a thing as a thermostatic diverter valve that would send the hot water through the finned pipe until the room was up to temperature and then divert the flow though the non-finned pipe to bypass it? I suspect not but thought it worth asking as there are all sorts of unexpected wierd things out there if you know where to look.
