Is it cheaper to have a separate timer for heating and water?

Spanishomelette

We live in a 1960s three bed semi and have gas central heating. We don't have a thermostat downstairs, just thermostatic valves on each of the radiators. We have a timer which controls both heating and hot water, so in the winter the water is heated for as long as the heating is on each day (about 7 hours a day during the week, more at weekends).


My question is, would it be cheaper to have a dual timer fitted so we only heat the water for a couple of hours a day in the winter, which is what we do in the summer?


The same goes for the central heating: although the radiators are turned down to zero in the summer, are we still paying for the central heating when the water is being heated. Or does it not make much difference?


Sorry if I appear a bit daft, but I really have no idea about how the heating works!

molerat

Yes it does make a difference. Although the water circuit will shut off when the tank reaches temperature using any water will set it going again. When you are heating water but have to have the heating circuit running there will be some flow into the heating. We used to have a system where we could have water on its own but when the heating was on so was the water. I replaced the timer with a fully independent dual circuit control and have seen a noticeable reduction in gas use. I assume you have 2 valves for the heating and water so it will be a relatively simple job to install a new timer.

matelodave

As Molerat says it would be better to try and get the heating and hot water circuits to be independently controlled by their own thermostats.

You'd need to have a look at your system to see how easy it would be as it's likely you don't have any controls on your system at the moment.

The timer/programmer probably just turns the boiler on to heat water and then switches the pump on for heating - the pump runs continuously when the heating is switched on.

The water temperature will be controlled by the boiler thermostat and so the boiler stays hot most of the time. You can't get much less efficient than that because the tank gets heated when the heating is on and the heating circuit conducts heat away when you only want to hot water. How good is your tank insulation?

Ideally you need a thermostat on the tank and a room thermostat (programmable stats are best) to control the heating. One or two motorised valves to separate the heating and hot water circuits and allow them to operate independently and to only fire the boiler when either of them call for heat.