I have a free standing boiler and when I switch on the heating for water or central heating it boils excessively and hot water spurts out of the hot water overflow pipe on the outside of the house. It only seems to happen in the cold weather when switching on the central heating for the first time as haven't had any problems during the summer when heating water only.

karen foster, October 2008

This is a tricky one karen but i think this is the pump that has been fitted the wrong way round and the boiler thermostat when on central heating is sensing the return water temperature instead of the flow temperature causing it to overheat.does your pump run when on hot water only or is it gravity hot water supply to your tank if it is gravity im sure this is the problem

stevie w, October 2008