Cost of immersion heater

hardpressed

How much does it cost to run an immersion heater for an hour?

inmypocketnottheirs

If you have a look on the immersion its self (not the copper cylinder) it will have a kilowatt/hour rating on it, normally expressed as kw/h. Then check your electricity suppliers charge per kilowatt hour, multiply it by the kw/h rating on the immersion and half it. Then you should have the approx running cost for half an hour. In my opinion its cheaper to heat via gas central heating if you have it.

Mikeyorks

Most immersions are 3kwh rated. So it will be around 24p / hour - from cold, with the immersion on all the time.

BUT - there is an (adjustable) thermostat inside the heater element set up - and this will cut off the power as soon as the tip of the thermostat senses the water around it is at the chosen temp. So - in effect the immersion is regularly cycling on / off, and it is difficult to ascertain the true cost without a monitor on the circuit.

If you have Economy 7 tariff - the cost will be only a third of the day rate for 7 hours during the night. And you would normally fit a timer to maximise use of the immersion during the cheap period?