Most efficient use of immersion heater

MoneyEM

I have just bought a new 1 bed conversion flat. The flat only has electricity (no gas) It is solely heated with an immersion heater and no boiler, and the heaters are all electric.

What is the best way to use the immersion heater to be most efficient? I work all day so would need hot water after 5pm on a weekday and at weekends

I called British Gas (my current supplier) and was told I couldn't get an economy 7 tarrif as I don't have storage heaters, so what would be the best way?

Swipe

The cheapest way would be to put it on just before you need it. Most immersion heater wall switches have a boost button that will switch off after 1 hour. This might be enough to heat your water for your needs. Mine takes about 45mins to get to temp in summer and about 70mins in winter. Alternatively, you could set the timer for the heater to come on at 3:30pm each day and go off at 5pm or however long it takes to get up to temperature.

Biggles

To be honest, I'd be worrying a lot more about the electric heaters than the small amount you'll spend heating water.

footyguy

MoneyEM wrote: »

...
I called British Gas (my current supplier) and was told I couldn't get an economy 7 tarrif as I don't have storage heaters, ...

What a very odd thing to have told you.

The only resaon you could not have an E7 tariff from BG would be if you do not currently have an E7 meter.

BG should be able to arrange to switch your current meter for an E7 meter for you if that is what you want (a charge may apply, typically £50-£70).

If you do have the meter switched, and later change your mind over which tariff you prefer, BG are one of the suppliers that are prepared to supply a single rate tariff with a dual rate (E7) meter.

cranford

If you re thinking about an E7 meter you need to bear in mind that normally the day rate is higher than the single rate for a non E7 meter. So the only way to tell if it will benefit you would need to estimate how much night rate you would use and how much day rate you would use and then use one of the comparison sites to find the best deal.
I think the general rule is that if a third or more of you use is at night then a E7 meter would be beneficial.
I have a domestic water tank heated only an immersion heater over night and heated to 65c and it takes 3.75 kwh. So the full tank takes about 1hr 20 mins to heat up. But the tank has built in insulation and the water is still warm at 10pm (unless we use the bath rather than the electric shower).
So if you were to switch on at about 3.30 until 5 you should have a full tank to come home to and maybe some warm water still there for the morning.
If you have not got one already 7 day time immersion time switch would be very handy for your weekends if you stay with a single rate meter.
As was mentioned before its the heating that will cost you the most so its very important for you to find a company that can supply at round about 10p per unit rather than the 14p or more on standard tariffs.
Heating could easily take 6hrs a day on working days at a minimum of 3 kwh per hour depending upon your insulation and temp needs. But at least thats only for 7 months a year!

Cardew

If it is a new well insulated Hot Water tank(normally with a thick foam jacket) the heat losses are surprisingly low. Often between 1.5 to 2kWh in 24 hours with the water at 65C. (you might find it stamped on the tank)

In any case this heat loss from the tank warms the fabric of the building so is not lost for much of the year.

So have experiment with the most convenient time for you to heat the tank, but be aware it is not a big issue; as said above, your heaters are far more important.