immersion heater

[sroncalew]

how long should it take a 3kw immersion heater to boil 300 litres of water

[buildersmate]

The physics involved in this is:
1 Watt equals 1 Joule per second
4200 (approx) Joules equals 1 KiloCalorie
1 KCal is the amount of heat required to raise 1 litre of water by 1 degree Celsius

So an answer in minutes:
(300*80*4200)/(3000*60) = 560 minutes

Assumptions:
80 degree Celsius temperature rise from 20 to 100
NO LOSS OF HEAT TO EXTERNAL

In reality the second assumption is just not going to happen and it will take a lot longer than that.

[Ethel]

Are you sure you want your immersion heater to boil water?

[buildersmate]

Quite so - which is why the theoretical time taken is so long. A typical immersion heater has only to take the temperature up to 60 degrees Celsius.

[Ethel]

Thanks, BM.

I thought either you, me or sroncalew had gone potty.