My glowworm combi ultracom 24cxi hot water is working fine. The boiler fires up to full capacity but when the tap is turned off the heating is just running at a low rate and the room temp is sitting at 17 degrees.. It won't kick in if I raise the boiler temperature or the thermostat temperature. The water icon is showing on the thermostat but not the radiator icon. Can anyone help please?

julie, January 2016