Immersion or Kettle?

Fiona1408

I am on an economy 7 meter with Scottish Power and have an immersion heater tank for water. I have the option to put the hot water on "timed" meaning that it only heats up at night using the cheap electricity. However, I live on my own in a flat with an electric shower. The only thing that hot water is used for is my bathroom tap and my kitchen tap. As I live alone the amount of hot water for dishes etc. I need is minimal. Is anyone else in the same situation or knows if it would it be more economical to use my kettle to heat water for washing up dishes, rather than turning on the immersion?
Thanks

[Deleted User]

The kettle will heat up say 2 litres of water whilst the immersion will have to heat several hundred litres of water.

So the kettle will be much cheaper if you only need the boiling water for a few dishes due to the quantity of water being heated.

We normally boil a kettle for the dishes and add cold water to get the washing water to the correct temperature.

AndyPK

just imagine how many pennys you could save, if you purchased a timer for your kettle, to come on at 6:30am and did your washing up in the morning. (leaving them to soak over nite)


That's partly a joke.




If your timer will allow you to have 15 mins of immersion heat during the econ7 period, that would be interesting to trial to see if the water is a usable temperature.

macman

A properly lagged tank will stay hot all day. And the heat lost serves to warm the house in winter anyway.
If you want to economise fully, the (if you have a gas supply), then heat your water on a gas hob, as that will be a third of the cost of E7 peak rate electricity.

PasturesNew

I lived in a flat for over 2 years with an electric shower - in all the time I lived there I never ONCE turned the immersion on whatsoever.

I did all the washing up by boiling the kettle.

I never understood why they didn't simply have little electric wall-mounted water heaters, like you used to see more often years ago. Free up the airing cupboard for storage purposes, far more useful.

WobblyDog

If your hot water cylinder is similar to mine, it contains about 140 litres of water and the average temperature drops by about 10 Celsius over 24 hours if no water is drawn and it's only heated once per day. I calculate your hot water cylinder consumes about 1.63 kWh per day.


A typical kettle is about 3kW, so if you can heat all the water you need by running the kettle for less than half an hour per day, the kettle will be more efficient. If I was using a kettle that frequently, I'd probably end up burning myself.


I'm assuming that heat lost from the hot water cylinder serves no useful purpose, but during the winter it's probably providing useful background heat in your house.


I reckon hot water cylinders heated by Economy 7 electricity are actually quite cost-effective, and probably better than older poorly designed gas installations like the one I've got in my house.

AndyPK

And is your immersion heater a dual one? where a small one can be used to only heat the top half of the tank?

Fiona1408

AndyPK wrote: »

And is your immersion heater a dual one? where a small one can be used to only heat the top half of the tank?

Yes it is dual, there is a small section at the top of the tank, I assume this is to only heat a small volume of water?

Cardew

Most well insulated hot water tanks lose very little heat. In post #6 the poster calculates 1.63kWh a day. That figure is typical of modern HW tanks which are tested to a British Standard with water at 65C*(it is often stamped on the tank). My modern 180litre tank loss is rated at 1.296kWh.
*In practice few people keep water at 65C so losses will be even smaller and on a decent E7 tariff that will cost less than 10p a day.

It also should be remembered that 'heat loss' from the tank isn't wasted for much of the year as it heats the fabric of the house.

[Deleted User]

Fiona1408 wrote: »

Yes it is duel

Duel by immersion heater? That sounds like an entertaining lark.

JJ_Egan

I use a gas kettle and find two full kettles is enough for a basin full of dirty dishes .