Help, water heater has been left on.

kezz

We are on economy 7 and have a water heater that has a booster switch. When I looked today I noticed that it has been knocked on by accident. Im not sure how long it has been on for and Im dreading the next bill. Does anyone know roughly how much this would cost weekly, a rough idea would be fine as Im really panicking now.
Thanks Kerry

Cardew

I would guess in the region of £5 a week for an average family.

kezz

Oh, do you think so? thats not as terrible as I thought, still terrible though.

ic

Just looked on Screwfix, the heating elements they do are all 3kW.

Assume a cost of 11.53p per kWh during the day and 3.74p per kWh at night (my prices from Ebico were I on economy seven).

Lets also assume 7 hrs night rate, 17 day rate.

So if it were heating constantly, we'd be talking £5.88 day rate, 78p night rate = £6.66.

However the heating is controlled by a thermostat in the tank and should only come on when the water needs warming up. Lets assume in a well insulated hot tank it would only need to top up the heat 15% of the time. That reduces that cost to £1 per day, or £7 for a week.

Obviously lots of a assumptions there, but should still be a reasonable idea.