water heating query

[Phil Pascoe]

If I need a gallon of water at 60c (without going into waste, pipework etc) is there any difference in electricity consumption between heating it on an induction hob and heating it in an immersion heater? Just a thought...

 

[artie]

On the hob you are only heating what you need, with an immersion heater you have to heat the whole tank.

Unless you are putting an immersion element into the 1 gal container, then there wouldn't be much difference.

 

[Phil Pascoe]

I meant pro rata, obviously.

 

[Jamesc]

By its nature there will much less heat loss and therefore greater efficiency with an immersion heater.

On an induction hob you are inevitably loosing heat to the surrounding areas as it is unlikely the water container will be a perfect fit on the hob. You will also lose heat in heating up the pan which in turn has to heat the water.

James

 

[John Brown]

By its nature there will much less heat loss and therefore greater efficiency with an immersion heater.

On an induction hob you are inevitably loosing heat to the surrounding areas as it is unlikely the water container will be a perfect fit on the hob. You will also lose heat in heating up the pan which in turn has to heat the water.

James

What he said(except for "loosing" ). As long as your tank is well lagged.

 

[blackrodd]

On the hob you are only heating what you need, with an immersion heater you have to heat the whole tank.

Unless you are putting an immersion element into the 1 gal container, then there wouldn't be much difference.

Are you sure that this is correct?
I thought the principle of the immersion heater was that hot water floats on top of cold water,
So when using the 2, or 3 stage immersion element, only the top 3rd or 2/3rds was heated.
Or the whole tank.
Regards Rodders

 

[Phil Pascoe]

OK - I'll re word the question. I have a 50 gallon immersion tank and a 50 gallon saucepan on an induction hob (hypothetically ). I need 50 gallons of water at 60c. Which is the more energy efficient, or are they both going to be the same? I'm not storing it or transporting it by pipes , I'm using it the second it hits 60c.

 

[flh801978]

The directly putting energy into the water is bound to be more efficient
Induction hobs will have there own inefficiencies rather than an element directly in the water

But I'd warm a gallon by gas hob !!!!

 

[Phil Pascoe]

There's probably more heat lost with a gas hob, though. It might be cheaper, but more efficient?

 

[artie]

On the hob you are only heating what you need, with an immersion heater you have to heat the whole tank.

Unless you are putting an immersion element into the 1 gal container, then there wouldn't be much difference.

Are you sure that this is correct?
I thought the principle of the immersion heater was that hot water floats on top of cold water,
So when using the 2, or 3 stage immersion element, only the top 3rd or 2/3rds was heated.
Or the whole tank.
Regards Rodders

Who can be sure of anything, it was how I saw it. The OP didn't mention 2 or 3 stage immersion heaters so I didn't consider them.

If placed on a hob the container has to be heated before the water, if an immersion is used the water has to be heated before the container. Both ways there is loss. You can't heat the water without heating the container and some of the air surrounding it as well as whatever is supporting it.

I think.

 

[flh801978]

Well in terms of efficiency then and electric element directly in contact with the water to be warmed assuming a well insulated tank you put 1kw of heat in and you get 1 kw of heat rise
but gas will be much cheaper even with its loss to the environs perhaps half the cost than electric to raise your 1 gallon 40 degrees

 

[Phil Pascoe]

What I was wondering was if it is more efficient to heat via a copper element or an induction loop - you are heating a piece of metal first both ways? I suppose if it were more efficient to use an induction loop, someone would have brought out a hot water tank heated by one.

 

[blackrodd]

On the hob you are only heating what you need, with an immersion heater you have to heat the whole tank.

Unless you are putting an immersion element into the 1 gal container, then there wouldn't be much difference.

Are you sure that this is correct?
I thought the principle of the immersion heater was that hot water floats on top of cold water,
So when using the 2, or 3 stage immersion element, only the top 3rd or 2/3rds was heated.
Or the whole tank.
Regards Rodders

Who can be sure of anything, it was how I saw it. The OP didn't mention 2 or 3 stage immersion heaters so I didn't consider them.

If placed on a hob the container has to be heated before the water, if an immersion is used the water has to be heated before the container. Both ways there is loss. You can't heat the water without heating the container and some of the air surrounding it as well as whatever is supporting it.

I think.

Just to clarify, You said that the whole immersion tank would have to be heated, not so.
I tried (badly) to point out that the element worked on the selected amount of water in the tank needed.
a 3rd of the tank, 2/3 rds of the tank or a full tank, from the top down.
I just used the word stage instead of tank.
Regards Rodders

 

[artie]

Just to clarify, You said that the whole immersion tank would have to be heated, not so.
I tried (badly) to point out that the element worked on the selected amount of water in the tank needed.
a 3rd of the tank, 2/3 rds of the tank or a full tank, from the top down.
I just used the word stage instead of tank.
Regards Rodders

Yes I appreciate that and I badly said that you need to heat all of the tank instead of, more properly saying more that the 1 gal. I don't think it is possible to heat exactly one gallon at the top of the tank without raising the temp of at least some of the rest of it.