Cheapest way to run immersion heater

snowqueen555

Hello

Anyone here use an immersion heater? Looking for the cheapest way to run it. Most flats I'm looking to buy don't have a gas supply. Can I get away with just turning it on once a day in the evening to cover having a shower and washing the dishes?

There's no way I can afford to have it on thermostat to keep it at a certain temperature all day.

Other option of having it turn on twice a day is going to cost too much as well. It costs £2.50 to heat a 165lt tank.

Dread to think how much it would be in winter.

P.S I work from home so am I screwed 😩 but typically done need hot water during the day.

I'm wondering if electric prices will eventually return to 15p per kWh at some point in the future as that would help knowing the prices we are seeing are temporary.

Thanks

Mstty

It is cheaper to boil a kettle for dishes than heating up a tank.

Just try heating for one hour see how much that gives you and then adjust as required.

Come winter hot water will become a luxury

k_man

As suggested above, the cheapest way is to heat only as much as you need, just before you need it.

As long as the hot water tank is well insulated, then the costs mostly relate to how much hot water you use, rather than when you heat it. Reducing hot water use is likely to save more than changing hot water times (assuming regular, normal hot water usage).

But if the tank is poorly insulated then you definitely need to follow the initial suggestion, and reduce hot water too (to get the cheapest solution).

MattMattMattUK

snowqueen555 said:

Hello

Anyone here use an immersion heater? Looking for the cheapest way to run it. Most flats I'm looking to buy don't have a gas supply. Can I get away with just turning it on once a day in the evening to cover having a shower and washing the dishes?

There's no way I can afford to have it on thermostat to keep it at a certain temperature all day.

An immersion heater only heats what needs to be heated. If you leave it on all day but the water in the tank is already hot then it will not turn be used for more than a few minutes to top up the very minimal loss as modern tanks are very well insulated. If you only run it for an hour a day, but use more water than it can heat in an hour then you will eventually run out of hot water. 

snowqueen555 said:

Other option of having it turn on twice a day is going to cost too much as well. It costs £2.50 to heat a 165lt tank.

It costs a lot more than that to heat a 165L tank from cold to temperature, how much it costs to heat up after your daily usage depends on how much hot water you can use.

snowqueen555 said:

Dread to think how much it would be in winter.

It will cost more as the input temperature of the water is lower.

snowqueen555 said:

P.S I work from home so am I screwed 😩 but typically done need hot water during the day.

I am not sure why working from home screws you?

snowqueen555 said:

I'm wondering if electric prices will eventually return to 15p per kWh at some point in the future as that would help knowing the prices we are seeing are temporary.

I very much doubt that they will. Russia is not going to come back from the invasion of Ukraine for decades, transitioning to zero carbon energy is going to cost a lot. We might get back to 30-35p per kWh in a few years time after this winter's rise to 43-45p but I would not bank on that. 

Being electric only is more expensive than having gas, but if you live well insulated property so heating is not a major concern then not hugely so. I would say that if £2.50 a day is unaffordable then I am not sure you can really afford to buy, £75 pcm should not be make or break when you factor in the mortgage and other costs.

Mstty

Being electric only with storage heaters and electric radiators is certainly more expensive but bold statements as having electric only is more expensive than gas is not true for all anymore. Having a heat pump now is directly comparable and even more so with the ratio of gas costs to electricity costs coming down to a ratio of 3:1

With the efficiency of heat pumps the tide will have turned come October/Jan this year for retro fit as well.

snowqueen555

MattMattMattUK said:

snowqueen555 said:

Hello

Anyone here use an immersion heater? Looking for the cheapest way to run it. Most flats I'm looking to buy don't have a gas supply. Can I get away with just turning it on once a day in the evening to cover having a shower and washing the dishes?

There's no way I can afford to have it on thermostat to keep it at a certain temperature all day.

An immersion heater only heats what needs to be heated. If you leave it on all day but the water in the tank is already hot then it will not turn be used for more than a few minutes to top up the very minimal loss as modern tanks are very well insulated. If you only run it for an hour a day, but use more water than it can heat in an hour then you will eventually run out of hot water. 

snowqueen555 said:

Other option of having it turn on twice a day is going to cost too much as well. It costs £2.50 to heat a 165lt tank.

It costs a lot more than that to heat a 165L tank from cold to temperature, how much it costs to heat up after your daily usage depends on how much hot water you can use.

snowqueen555 said:

Dread to think how much it would be in winter.

It will cost more as the input temperature of the water is lower.

snowqueen555 said:

P.S I work from home so am I screwed 😩 but typically done need hot water during the day.

I am not sure why working from home screws you?

snowqueen555 said:

I'm wondering if electric prices will eventually return to 15p per kWh at some point in the future as that would help knowing the prices we are seeing are temporary.

I very much doubt that they will. Russia is not going to come back from the invasion of Ukraine for decades, transitioning to zero carbon energy is going to cost a lot. We might get back to 30-35p per kWh in a few years time after this winter's rise to 43-45p but I would not bank on that. 

Being electric only is more expensive than having gas, but if you live well insulated property so heating is not a major concern then not hugely so. I would say that if £2.50 a day is unaffordable then I am not sure you can really afford to buy, £75 pcm should not be make or break when you factor in the mortgage and other costs.

I can afford £2.50 a day, that is just the cost to hear the tank up once. I need to factor in the electric for everything, plus the fact most people use their immersion heater for a lot longer than this. I figure the monthly bill might be around £150+ and that's without heating.

I believe it's been mentioned a few times but it is a myth that keeping the tank warm all day with a thermostat is cheaper than turning it on only when needed.

WFH costs more as in the winter I will need to use the heating a lot more.

QrizB

I'm going to disagree with MattMattMattUK here, which is a fairly rare occurrence:

MattMattMattUK said:

snowqueen555 said:

Other option of having it turn on twice a day is going to cost too much as well. It costs £2.50 to heat a 165lt tank.

It costs a lot more than that to heat a 165L tank from cold to temperature, how much it costs to heat up after your daily usage depends on how much hot water you can use.

Heating 165 litres from 10C to 60C will take a smidgen less than 10kWh. That's about £2.85 at current prices - which I wouldn't describe as "a lot" more than £2.50.

MattMattMattUK said:

snowqueen555 said:

Dread to think how much it would be in winter.

It will cost more as the input temperature of the water is lower.

The effect is fairly small. Heating those same 165 litres from 0C will take 12kWh, £3.42.

If your incoming water is below 0C you've got bigger problems to deal with.

Getting back to the question:

snowqueen555 said:

Anyone here use an immersion heater? Looking for the cheapest way to run it. Most flats I'm looking to buy don't have a gas supply.

I had a house with an immersion heater for water and storage heaters for space heating for nine years.

Assuming you don''t have free electricity (eg. from solar), the cheapest way to run an immersion heater is during the off-peak period of a multi-rate tariff.

Most all-electric flats should have Economy 7 (E7) or a similar multi-rate electricity tariff. When compared to a single-rate tariff this gives you an off-peak period with much cheaper electricity at unsociable hours of the day (usually overnight) and somewhat more expensive electricity the rest of the time.

Can I get away with just turning it on once a day in the evening to cover having a shower and washing the dishes?

The purpose of the well-insulated hot water tank is to let you heat the water on the off-peak tariff and kep it hot until you need to use it. So you'd heat the water tank during E7 hours and it will stay hot all through the day until you need to shower and do dishes in the evening.

For an example, see EDF's tariff table here. In the East Midlands & paying by DD (the first line on the table) E7 gives you seven hours a day at 13.4p/kWh and the remaining seventeen hours at 35.28p/kWh.

Heating your hot water tank during the E7 off-peak period would cost £1.34. Heating it at other times would cost £3.53.

There's no way I can afford to have it on thermostat to keep it at a certain temperature all day.

The tank will have a thermostat but your main control is the timeswitch (usually the one inside your electricity meter that switches the E7 circuits on and off automatically).

k_man

@QrizB
Good point on E7, forgot about that completely 

snowqueen555 said:

I believe it's been mentioned a few times but it is a myth that keeping the tank warm all day with a thermostat is cheaper than turning it on only when needed.

WFH costs more as in the winter I will need to use the heating a lot more.

I don't think anyone is suggesting it is cheaper to leave the hot water on all day or for long periods,  more that the claims of extra cost are vastly exaggerated, E7 aside (assuming the tank is insulated).

And the more common myth arguement area of debate, is usually around heating (rather than hot water) on all day vs timed, but we should not go there yet...

[Deleted User]

Hi,

are you on E7, if so, heat water on cheaper rate for an hour before you get up in morning, a well insulated tank should keep warm enough.

Boil a kettle to wash up dishes.

markin

Unless its a brand new flat you need to make sure you buy a place with storage heaters not panel heaters and its wired for E7 but either way you will need to use around 6-7000kwh for heating or live/work in a cold flat.

macman

Bear in mind that any heat lost from the tank during the day  or night is not wasted in winter when the heating is on anyway, as it serves to heat the property.
If it's running off E7, then you need to be heating during the cheap rate hours, which is not during the evening, but overnight.