Water Heating

[Le Chat]

Is it cheaper to heat the water for my home in the summer, for one hour, by switching on the water tank (electrically) or by having the gas central heating on and the thermostat so low that only the water heats? We do not have a combi boiler.

[barry1010]

If the central heating is on that low the water won't be very hot.

How much hot water do you usually use in a day? My showers are electric so don't use the hot water, my washing machine and dishwasher are cold fill so we don't use much hot water. Before I had the combi boiler I switched the immersion heater on for 20 minutes to half an hour a day.

[The Builder]

Gravity systems (non-combi) usually have a control set-up that gives priority to 'hot water' over 'heating.'
If it's warm enough for heating not to be needed, then there's no need to set a low temperature on the 'HW'.

Whether you use the boiler or the immersion, using short bursts of power is rarely economical. It's much more efficient to use set times to keep the tank topped up, especially with modern well insulated cylinders. Heating them up from stone cold is very inefficient.

A lot of folk do still insist on using short bursts though. If you do, I would say the immersion would make more sense since that's all you're heating up. Otherwise, you have to use a lot of energy heating the whole boiler up.

[Le Chat]

Barry1010. It's really only to heat the water for my son's bathroom. Mains fed rather than electric shower. We have elec in our en suite.

[Le Chat]

The builder. Our boiler is over 30 years old bit has never broken down, so my attitude is, if it ain't broke, don't replace it

[barry1010]

If your central heating boiler has a hot water only setting use that. If it doesn't use your immersion heater.
My old central heating boiler couldn't heat the water without having the heater on