Gas or Electric for summer hot water

Vintage_Richard

My (large) central heating boiler just heats the hot water in the summer. I also have an immersion heater but not off-peak cheap electicity. Which should I use?

HappyMJ

If you do not have an E7 tariff then the gas boiler will most probably be cheaper.

macman

Gas is about 4p per kWh, Standard rate electricity is about 12p per kWh. So even allowing for the relative inefficiency of the gas boiler, it's still much cheaper.

molerat

Agreed, I did a trial a couple of years ago and found that the gas to be way cheaper even with an antique boiler.

jalexa

Vintage_Richard wrote: »

Which should I use?

IMO it is no bad thing to have the boiler excercised regularly. (and also to test the immersion heater from time to time)

Pincher

I think modern boilers tend to run the central heating pump once in a while to stop them seizing up. So if you were planning to switch off the power to the boiler, ho hum.

macman

My Honeywell programmer is set to run the CH pump for a few seconds at mid-day throughout the CH 'close season'. The manual calls it 'pump exercise'.

Candy53

We've found it works out quite alot cheaper to use the gas to heat the water.

Candy

meg72

I find it so much cheaper to use gas.

gyromain

Over the last 2 days of summer weather I have measured how much gas I have used heating hot water only. Over the 2 days, gas used 3.69 cu ft - 1.845 cu ft per day.
Gas units are converted to kilowatt hours using the following
1.845 x 2.83 x 39.4 x 1.022640 / 3.6 = 58.44kWh
58.44kWh x 3.616p = £2.11 per day!

Immersion heater 3kW takes 2.5 hours to heat tank from cold.
3 x 2.5 = 7.5 kWh x 6.149p E7 = £0.46
When using the immersion heater we only occasionally run out of E7 heated water and have use day units on the boost button.

I must switch the immersion heater on.

Pincher

gyromain wrote: »

Over the last 2 days of summer weather I have measured how much gas I have used heating hot water only. Over the 2 days, gas used 3.69 cu ft - 1.845 cu ft per day.
Gas units are converted to kilowatt hours using the following
1.845 x 2.83 x 39.4 x 1.022640 / 3.6 = 58.44kWh
58.44kWh x 3.616p = £2.11 per day!

Immersion heater 3kW takes 2.5 hours to heat tank from cold.
3 x 2.5 = 7.5 kWh x 6.149p E7 = £0.46
When using the immersion heater we only occasionally run out of E7 heated water and have use day units on the boost button.

I must switch the immersion heater on.

So you use 58.44kWh to heat by gas,
but 7.5kWh by electricity?

This would imply that your gas boiler is 12.8% efficient (7.5/58.44).