25l calorifier

[Vara]

Water at 15°C, how long should it take a 1kw immersion heater to take it to 70°C ?

 

[Momac]

About one and a half hours.


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[VicS]

1 hour 36 minutes assuming no losses

 

[Buck Turgidson]

My rough calculation would be 35°C per hour excluding losses. So probably a couple of hours should do it.

 

[David2452]

The above are correct in theory, that is according to simple numbers, however in practise the element may not be exactly 1000w, could be <>, have calcium deposits etc also it is rated at a voltage it might not quite be getting. The element, also, will not only be heating the water but the insulation, case and air surrounding it so more of an approximation. The main two contributors causing deviation from the numbers would be voltage and poor insulation.

 

[JohnGC]

Water at 15°C, how long should it take a 1kw immersion heater to take it to 70°C ?

If the immersion heats the water evenly, if it is exactly 1kW and if there are no losses (Eg no heating of the calorifier). Then it will take 96 minutes.

But the element will have a tolerance, the main supply voltage to the element could be higher or lower than 230V and some energy will be used to heat the calorifier itself.

Say +/-20% (just a guess). 75 to 115 minutes.

 

[Vara]

Thanks all, you have confirmed my arithmetic.

Must grovel about in the depths of the bilge as it seems to reach temp in about half an hour, so either calorifier is a third of the size I bought or I have an oversized immersion heater.

 

[David2452]

Thanks all, you have confirmed my arithmetic.

Must grovel about in the depths of the bilge as it seems to reach temp in about half an hour, so either calorifier is a third of the size I bought or I have an oversized immersion heater.

Or the water at the top (take off point) is 70c and the water below it is not at that temperature yet.

 

[Momac]

The time calculated is to raise the entire 25 litres of water by 55 degrees using a 1kW heater.

You can expect to get get some hot water after a much shorter time , say enough to do some washing up . My crew says we can get some hot water after about 15 minutes.
I don't know what capacity our immersion heater is , but very possibly more then 1kW.

.

 

[Vara]

Or the water at the top (take off point) is 70c and the water below it is not at that temperature yet.

Ah no, I ran off almost 20 l and the temperature was pretty constant, I suspect that my immersion coil is bigger than I thought, which is why in winter I sometimes blow the mains breaker, which with immersion, small kettle and 1kw heater I shouldn't.

I did have lots of outside jobs to do today, but it was too hot....can't often say that in Dover, so I was looking for something to do!

 

[Hydrozoan]

I very recently fitted a 22l calorifier with a 1kW immersion and I get plenty of hand-hot water (after mixing valve) in less than an hour. I deliberately chose a 1kW immersion for speed but also have a 2kW heater, so I put in a 1-0-2 rotary cam switch to avoid both being on simultaneously and the risk of tripping the breaker if someone decides to boil a kettle as well. With a bit of forethought, the either/or option isn't proving to be a problem.