We have a traditional hot water system that uses a storage tank for the hot water, the heating of the water is primarily through a gas boiler with an electrical immersion heater as back up.
I would like to connect the electric immersion heater up, so it works when the Gas boiler switches to heat the water. Thus reheating the water at a much faster rate.
I have tried to adjust the thermostats so they work in tandem, but have been unsuccessful, either the water is heated to too high a temperature or the electrical immersion does not kick in.
I was thinking of some sort of relay device that would switch the electrical immersion heater on when the motorised valve is switched to open, but what sort of relay would I buy and where from.? And if this was implemented would it still just heat the water to the same temperature as set for the gas boiler or would the water still be overheated?