How should I heat my water?

TrickyDicky

Hi All

Wondering if anyone has any input on how we should heat our water. We are with scottish power (online energy saver 21). We had a new Worcester Boiler installed a couple of years ago, and currently use this to heat our water in 2x30 min windows (one morning for showers, one evening for little ones baths and washing up etc). We do have economy 7 and an immersion heater, and I have always wondered if it would be any cheaper to use this instead of the boiler for the hot water.

Dishwasher and washing machine always timed for overnight runs.

Currently spend £106/month (it used to be about £80, but price rises, tarrif change and long winter upped the monthly bill!)

Any thoughts?

HappyMJ

How is your cylinder set up?

It's likely the immersion heater is only a backup for your gas boiler in case it's broken on christmas eve all you need to do is turn the immersion heater on and you have hot water then get some electric heaters together for heat and you can wait a few days before calling in a gas engineer.

It is cheaper to heat the water using electricity just before the E7 hours expire then have the boiler finish off the job for another half hour....but it's also unlikely that you have a timer on your immersion heater and buying one will not be worth it so just leave it off and use only in case of emergency. Check it still works before winter by turning off the boiler and using it.

The top immersion element will only heat a small amount of water for use in case of emergency...it's enough for a half a bath mixed with cold enough to have one bath...it does not heat the whole cylinder. The time whilst you are in the bath it's reheating so you can have another bath within an hour.

victor2

It's an interesting thought, I suspect it will be a close call between which is the most cost effective. You'd have to experiment to see.
Assuming your hot water tank is well insulated, run the immersion heater for, say an hour (the thermostat will presumably cut it off when it reaches the set temperature), during the cheap rate hours so that the tank is nice and hot for the morning showers. See if there's still enough warm water for the little one's baths in the evening.
Read your electricity meter before and after the immersion cuts in, ideally you don't want anything else running during those hours. If your fridge is on the economy 7 feed then you'll have to adjust the usage to allow for that - with further tests without the immersion heater running!
Then use your gas for the hot water, read the meter, convert it to kWh and see what that has cost. Needs to be done in similar weather conditions and for something like a week each really. Then compare the costs and convenience of the hot water supply to get an idea if it's worth it, and you've still got the will to live.