Electric only with immersion boiler - which is cheapest?

jt1413

Hi,

I live in the north of scotland, have a standard domestic electric tariff and my hot water and radiators are electric. 

The house has an immersion boiler with a large tank and a small boost tank at the top. We've been turning on the boost tank for 90 mins overnight for the cheaper tariff, but we have to do this every night and take really quick showers and sometimes boil the kettle for washing up etc in the day. We heat the large tank oncce every few weeks just to keep it ticking along. 

Is what we're doing actually cheaper than just putting the large tank on once every couple of days, and getting a lot more hot water or putting the boost tank on for 90 mins every night? We've never lived in an electrically heated house and to be honest have no clue what we're doing with regards to them. We figured less water = less money but really aren't sure.

Annoyingly there is no timer on the tank so we can't programme it to come on at night to get the night rate, we have had too do it manually each night.

[Deleted User]

Are you on an E7 tariff? If so, you are probably better off heating the whole cylinder at the offpeak rate. Usually, the bottom immersion heater is connected to the Offpeak supply and the top immersion heater to peak (but I have no idea of your particular configuration). Electricity is 100% efficient, and most well insulated cylinders have a very low heating loss rate of between 1 and 2.5kWh a day depending on cylinder size.

FWiW, my 250l unvented cylinder has required 2.2kWh of heating so far today. My wife has had a bath and I have had a shower plus the usual washing up etc. Based on previous days, I would expect my reheating to use 3kWh.

[Deleted User]

Hi,

you say your hot water and radiators, do you mean storage heaters?

If so, are you on E7, a day/night rate, that's a two rate tariff, will show on your bills.

If you are E7, then best to heat water on night rate, will click on when night rate clicks in.

markin

"standard domestic electric tariff" Do you mean the price cap tariff? If you mean your on a normal Singe rate not E7, E10 or Scottish version your wasting your time doing it at night if its just to save money.