Oil or electric water heating

Neilydun

Hi, I was wondering if anyone could help with which method of water heating is more cost effective ?
I have a 210ltr Megaflow, with 2x heating elements at a total of around 6kw. On my electric tariff between 12.30-4.30 I get a 5p rate.
Or, its heating with my oil boiler, condensing, roughly 4 years old, buying in Kerosene at a variable rate, but normally around 50p a litre.
Our house is busy, with at least 6 of us in the house all of the time, but often more like 8. We use a lot of hot water, and one tankful a day will not cut it either way.

doodling

Hi,

You don't say what your electricity rate is during the day so I can't be definitive but you need to bear in mind the following:

1. 1 litre of oil is around 10kWh, possibly slightly less after boiler efficiency is taken into account.
2. If your oil costs 50p a litre then the cost is just over 5p per kWh.
3. Is the oil really 50p a litre, current prices for oil suggest more like 57p a litre (since September)?
4. If oil was 50p a litre then there probably isn't much in it price wise between overnight rate electricity at 5p per kWh and oil.  (and factors like variations in boiler efficiency depending on whether the boiler is also heating the house overnight may tip the balance one way or the other).  The electricity is probably very slightly cheaper but not by much.
5. If oil was 57p a litre then overnight rate electricity is cheaper.

Unless you can get electricity during the day at the same rate as overnight (please tell us where if you can!) then during the day oil will be cheaper.

Reed_Richards

If you only ever use the 5p rate electricity there won't be much in it.  Heating oil burned with 100% efficiency should give you 10.35 kW per litre.  So if your boiler can manage 90% efficiency that's 5.37 p per kW,  if you pay 50p a litre for your heating oil.  

QrizB

Jst adding to everyone else, as the prices are so similar and you need two tankfulls of hot water a day why not heat one overnight with 5p electricity and the second later in the day with oil?

Neilydun

Reed_Richards said:

If you only ever use the 5p rate electricity there won't be much in it.  Heating oil burned with 100% efficiency should give you 10.35 kW per litre.  So if your boiler can manage 90% efficiency that's 5.37 p per kW,  if you pay 50p a litre for your heating oil.  

Ok so barley anything in it, as prices stand. I would only be using electric on the cheap rate, and then oil when topping up.
As there is barley anything in the costs, I will just use oil, as its hit the button, then 15 mins later hot water is available.

Thanks for the replies.