The domestic hot water only get warm. I changed the pressure sensor as stated but still no luck. I did realise that the central heating gets warm when i leave the domestic hot water on but CH switch is off. Can anyone advise ?

Kully, June 2009

it is a blocked hotwater heat exchanger, when the hot tap is turned on the pump sends water from the primary heat exchanger to the domestic hot water heat exchanger. due to the blockage in the domestic exchanger the primary hot water is passing the 3 port and going to the heating circuit.
the 3 way valve is often blamed for the problem. :(

kiaora, July 2009

I will try and clean out the system, including diverter values and heater exchange. Cheers Mate

Mr K, June 2009

Your diverter valve letting by heat to the radiator so water is not getting hot, could be diverter valve motor faulty if any or diverter valve have sludge stuck in.

Mr K, June 2009