Immersion Heater - Costs...?

[joko]

can anyone give me an idea of how much an immersion heater costs to run for say, an hour?

on occasion i have switched it on and accidentally left it on for a few days - so i am wondering how much it actually costs - to remind me to be more vigilant about turning it off again

its a standard old style copper tank, with one element.

thanks

[chrisgel]

That would depend on how well your hot water tank is lagged. If well lagged the water will reach it's temperature and the heater will turn off until the temperature drops.
So it's not as if the heater is drawing power all the time.

[gingejbee]

A 3kW immersion could cost (depending on tariff) 40 to 60 pence an hour. However, if the thermostat is working power won't be used for much of the time once the set temperature is reached - just "on" to maintain that temperature.

[2sp_]

I was always under the impression that it works out cheaper to leave your immersion heater on all the time rather than just boost it when you need hot water.

The thought is that the water will only be heated when it drops below the set temperature and, if your tank is properly insulated, the water will maintain a steady heat.

This works out cheaper than having to heat an entire tank of water from cold.

I'm happy to be corrected if I've been wrong all these years!

[gingejbee]

2sp: I think that there are too many variables for a definite answer. Depends on temperature of incoming water, how hot you set the thermostat, how much hot water you will need on any particular day, what volumes are drawn each time, how good the insulation etc etc. Not quite as simple as a yes or no!

[joko]

thanks all

i didn't realise it switched off when the temp was reached - i thought it had been almost boiling away on full for days.

[2sp_]

It's a bit like setting your thermostat for the central heating. The heating only comes on when the house drops below the set temperature. Same with your immersion.