Should I leave emersion on all day, or only when i need?

JDMYOFAN

We've very recently moved into a new place (renting) and as it's our first home, just need to know a few moneysaving hints!

Should we leave the emersion on all day, or only when we need it?

Our idea is to have it switched off from 9pm - 5pm the next evening (Whilst we sleep through to us getting back from work at 5pm). We would leave it on for 4 hours or so then switch it back off as it keeps the heat in...

There's a bit of an arguement... keep it hot at all times, as it doesnt use much electric to 'top it up' compared to heating it from cool, or is it wasting electric by having it constantly on?

I look forward to the debate!

Thanks

newlywed

Our immersion heater costs about £1 for each hour it is on heating the water. (we are on prepayment meter so can monitor this easily). Doesn't seem to make much difference if the water is already warm or not.

Then again, I don't think we have a temperature gauge when heating on immersion - only when we heat it by gas boiler.

When our gas boiler broke down we did discover that just over half an hour on immersion was plenty of hot water for a bath in the evening - even though it hadn't been on at all during that day.

JDMYOFAN

£1 an hour? seriously? oh crap

Horace

I have an immersion heater in my flat - I switch it on and off when I need to, I never leave it on all day. If it has a good jacket on it, it should stay hot/warm for a reasonable length of time.

espresso

nj106 wrote: »

£1 an hour? seriously? oh crap

A standard immersion heater rated at 3 kWh would cost approx 30p per hour to use. As Horace said, if your tank is well insulated a short burst of say 30-40 minutes to heat up a tankful, should stay hot for ages.

JDMYOFAN

espresso wrote: »

A standard immersion heater rated at 3 kWh would cost approx 30p per hour to use. As Horace said, if your tank is well insulated a short burst of say 30-40 minutes to heat up a tankful, should stay hot for ages.

Thanks, so a quick burst before we go to bed and maybe a quick one as soon as we get home should do it nicely..

is that 30p per hour for the full tank? as it;s only 2 of us, we only have the top half kept warm.. so is that 15p per hour??

Thanks!

espresso

nj106 wrote: »

Thanks, so a quick burst before we go to bed and maybe a quick one as soon as we get home should do it nicely..

is that 30p per hour for the full tank? as it;s only 2 of us, we only have the top half kept warm.. so is that 15p per hour??

Thanks!

Yes if you haven't got a timer. Ideally a burst before you get up and then another early evening. An immersion will cost the same to run regardless of the size of the tank, number of people etc. as it just burns electricity at a constant rate until the thermostat switches it off. e.g. 1kWh costs say 10p per hour, so 3kWh costs 30p per hour or 10p for 20 minutes use.

espresso

newlywed wrote: »

Our immersion heater costs about £1 for each hour it is on heating the water. (we are on prepayment meter so can monitor this easily).

It sounds like your prepayment meter is programmed to recover a debt.

Cardew

What you haven't made clear is what form of heating you have.

If you have gas then you never use the immersion heater.

If you have Economy 7 Electricity you have it on during the night cheap period.

However assuming you are using normal daytime electricity rates:--

Firstly £1 an hour is rubbish.

The 30p an hour is the rate when the immersion heater is actually heating the water. When the water reaches the set temperature it switches off and doesn't draw power. It probably would never take a full hour to heat a tank.

How long the immersion heater is actually heating(as opposed to being switched on) for depends on the size of tank, how well it is insulated and of course how much water you use.

For instance the contents of the tank will probably still be warm after you have used some in the morning. In the afternoon it might take, say, 20 mins to bring it back up to full temperature; and that will cost 10p.

It really is trial and error to find the minimum time the immersion needs to be on for to provide sufficient hot water for your individual needs.

Ideally you should have a timer fitted and have it on for, say, 30-40 minutes just before you get up and another 30-40 minutes just before you come home.

mech_2

Immersion heaters have a thermostat, so it's not as simple as saying "x amount of time costs y" based purely on its power rating and cost per unit of electricity. If you have a 3kW immersion heater and you switch it on for an hour, that doesn't mean the element is on for an hour. Though obviously such a calculation does provide a maximum figure.

A well lagged tank will therefore also have some effect on power consumption, in addition to keeping the water warm for longer after the heater is switched off.

On the other hand, I think this is a bit hard to believe:
http://forums.moneysavingexpert.com/showthread.html?p=313647

tomstickland

Best to turn it on when you need it. Otherwise it'll sit there all day using up electricity to cover the lost heat. In the winter this will be heating the home, so not totally wasted.

I use Econ 7 and only heat water over night.