Any One Understand Gas And Electricity Unit Prices?

[hc4361]

I need to know if it is cheaper for me to heat my hot water by electric immersion heater water tank or by gas central heating for one hour.
The unit costs are:

Electricity 6.18p
Gas 2.45p

The immersion heater is 3kw.

[Old_Geezer]

I can only guess and I'd guess gas. But you should have details on the kw or therm cost per unit so can work out which provides power cheaper.

[Old_Geezer]

You didn't say whether the units you show were all the same for both. You need to convert first. The bill probably shows that for you.

[Old_Geezer]

I suspect you already have the gas in kWhrs ? In which case gas is the lower price by direct comparison. (Ignoring standing charges.)

On my gas bill the meter reading, which I assume is in therms, is converted to kWhrs by multiplying by 31.7 (approximately).

I assume your electricity figure is already in cost per kWhr.

If your unit was the meter reading, then the unit price for gas is not only already lower, it seems the gas unit is many kWhrs so it would be ridiculously cheaper.

[hc4361]

Thanks, OG, according to my bill both figures are KW.

What I don't understand (as well!) is how many KW does one digit on my meter use?

[Old_Geezer]

The electricity I think reads directly in kWhrs, but it should say on the meter.

According to my gas bill it looks to me as if 1 meter digit is 31.7 kWhrs.

As mentioned I thought they were therms but I guess they could be cubic meters volume ?

[bhg481]

Just to make life even more complicated, you need to know how efficient your gas boiler is. The electricity consumed by an immersion heater is almost all used in heating the water; you will be aware that hot air comes out of your boiler flue and that is wasted energy. The other thing to bear in mind is that the immersion heater only heats the water in the top of the tank, since the element doesn't reach right to the bottom; the gas boiler heats a different amount, depending where the inlet and outlet to the cylinder are.

[hc4361]

Such a simple thing but so blerdy difficult. :(

[Old_Geezer]

Fair enough, but at what looks like gas being under 40% cheaper it's have to be very inefficient.

[Old_Geezer]

Under 40% of the other
NOT cheaper !
It is around 60% cheaper.
We need an edit facility.

[gingejbee]

...it also depends on how much hot water you want, how hot you want it, if you want it available all day or just at specific times....and probably several other variables that I've not thought of! Virtually impossible to answer, in fact (cf...how long's a piece of string).

[GRUMPY]

I would say that Gas is much cheaper

[bhg481]

Let's make it even more complicated. Every time you switch on the gas boiler you waste a boiler full of hot water plus the water in the pipes feeding it. In winter, when the heating is on, this is less of a waste than in the summer, when the boiler is only used to heat the water; it may be cheaper to use the immersion heater in the summer and the CH boiler in the winter.
Do you have a timer on the immersion heater? If not, getting one installed professionally may cost more than any savings anyway.

[hc4361]

I do have a timer on the immersion, it comes on for one hour a day in the summer, during the off peak Economy 7 hours

[EDDIE51]

1 hour on the immersion heater should heat the entire tank to the set temperature , normally 6o deg C. If your tank is well insulated that will last all day.If you use off peak electricity that will be the cheapest way.

[hc4361]

It's very well insulated and I've never run out of hot water. Showers, dishwasher and washing machine all use cold water only

[hc4361]

Am I right in thinking the 1 hour of immersion heater costs a maximum of 18.54? Obviously it cuts out if it reaches temperature before the one hour is up

[bhg481]

Your assumption is correct hc4361, assuming that the 6.18p per KWH is the Economy 7 rate.
Just out of interest, we have an insulated tank but I put a jacket on top of the insulation. On one occasion we went away for 4 days. I was having a shower the morning after we got back and the water was only just warm enough. Then I realised I'd forgotten to turn the water heating back on.
Another thought, 60 deg is too hot to put your hands in; try turning the thermostat on the immersion heater down by a few degrees.

[paddywak]

It all depends on the size of the immersion heater for instance a 3kw heater running for an hour will use 3kwh or units the average price of electricity at the moment is about 14p/unit or for a 3kw heater 42p/hour.these prices of course vary according your supplier and tarrif

[BRIGHT SPARK]

Put the immersion on until the required temp is reached from cold and check the leccy reading....then when the water is cold again do the same again with the gas..the gas should be cheaper,unless you have a boiler problem.

[ivor4781]

Electricity 6.18p ... wow give me the name of your supplier !!