Conventional central heating system with a water cylinder and three port valve in the airing cuboard.
Recently, the radiator in the bathroom has been getting warm when switched to "hot water only". It didn't do this before.
My thoughts are that the three port valve is sticking. Other than this maybe the heat exchanger in the cylinder has failed. Any other suggestions as to the cause?
How to diagnose whether 3 port or cylinder?
sponix