Water heating

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gar

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Location
Ann Arbor, Michigan
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EE
181201-1500 EST

Is it more efficient to heat a cup of water from 70 F to 180 F in a microwave, an electric pot, or are they the same?

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from my own studies... In order from highest energy use to lowest energy use:
UK style Electric Kettle
Under cabinet Hot Tap
Hot Bottle Tap (Office Style)
Drip coffee Maker
Microwave
Pod coffee Maker

However, then we have the speed factor, with microwave amd hot tap both coming in first, the UK style kettle second and the pod running last.
So, for my solar situation, I have the following.. gas fire kettles that can be on wood, UK Kettle, because sometimes you need more than just a cup of coffee, the Pod system, and the microwave... I dont use the microwave however for hot water because of flashover... you put a spoon in it and because the surface was broken it suddenly turns into steam that boils on your hand, face etc.
 
My electric kettle is way faster than my electric stove. I usually heat a kettle full of water to boiling, then pour it into a pot for cooking.
 
Coppersmith said:
My electric kettle is way faster than my electric stove. I usually heat a kettle full of water to boiling, then pour it into a pot for cooking.
Click to expand...

I do the same.. the cost savings for making spaghetti or soup alone is amazing.. though more expensive, minute per minute, quicker as well, so overall time is less.. i even have taken to heating the water in the kettle and pouring it hot over my eggs then boiling four minutes on the stove..shells come right off..
 
An electric kettle will be more efficient than a microwave oven.
In an electric kettle, pretty much all of the energy goes into the water.
In a microwave oven, much of the energy heats the magnetron and a fan blows it away.

The difference is probably too small to be concerned with if you're only heating the occasional cup of water,
and the energy wasted by the magnetron contributes to heating your house.
 
Adamjamma said:
from my own studies... In order from highest energy use to lowest energy use:
UK style Electric Kettle
Under cabinet Hot Tap
Hot Bottle Tap (Office Style)
Drip coffee Maker
Microwave
Pod coffee Maker

However, then we have the speed factor, with microwave amd hot tap both coming in first, the UK style kettle second and the pod running last.
So, for my solar situation, I have the following.. gas fire kettles that can be on wood, UK Kettle, because sometimes you need more than just a cup of coffee, the Pod system, and the microwave... I dont use the microwave however for hot water because of flashover... you put a spoon in it and because the surface was broken it suddenly turns into steam that boils on your hand, face etc.
Click to expand...

Good list and info.

While water can get super heated in a microwave, in particularly something like a clean Pyrex measure with a lack of nucleation sites, and spontaneously boil when disturbed, turntables reduce that somewhat, as well as putting in a small rock or boiling chip, which effectively gets rid of the risk all together.
 
Good question, but I will need to ask the wife; I don't know where the coffee comes from.
 
181201-1938 EST

So far drcampbell is the only one that clearly read and understood the question, and provided a very concise answer.

Back in 2011 I ran such an experiment. The hot pot was about 95%, and the microwave about 42%.

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gar said:
181201-1500 EST

Is it more efficient to heat a cup of water from 70 F to 180 F in a microwave, an electric pot, or are they the same?

.
Click to expand...

Neither: right out of the tap next to Heat pump WH, then on induction cooktop.
To be a fair comparison, one must know the mass and material of the pot if just uwave to cooktop comparison. For the electric pot, you gotta heat the pot so for just 1 cup, you are heating the pot also. 1 cup in a styrofaom cup in microwave you are pretty much only heating the water.

If the uWave is only 50% efficient, the mass of the electric pot and cup needs to be less than 16 oz times pot+ heater mass x pot/heater specific het.
 
gar said:
181201-1938 EST

So far drcampbell is the only one that clearly read and understood the question, and provided a very concise answer.

Back in 2011 I ran such an experiment. The hot pot was about 95%, and the microwave about 42%.

.
Click to expand...

You were asking about electrical efficiency then. That was not the only option based on your post.

Since you already have the results, does a hot pot heat a cup of water faster (temporal efficiency) than a microwave of an equal wattage?
 
gar said:
181201-1938 EST

So far drcampbell is the only one that clearly read and understood the question, and provided a very concise answer.

Back in 2011 I ran such an experiment. The hot pot was about 95%, and the microwave about 42%.

.
Click to expand...

Not true. He is the only one that added inferences. You did not give any clarity of what you meant by an electric pot.
 
181201-2148 EST

I did not define a microwave more accurately than the electric pot. drcampbell understood the concept of the question, and added some additional comment.

There were some assumptions in my question that did not need to be presented. Had altitude been a factor, then other information would have come into play. The temperature range indicated was to get away from both freezing and boiling, and to somewhat imply standard pressure conditions. Whether one method was faster or more convenient was not in the question. The difference in efficiency is so great that the container was not of great consequence.

The purpose of my question was not that I needed an answer, but to stimulate some thought.

If you thought the question was impossible to solve, or you did not undcerstand the question, then the obvious thing to do is ask a question to try to get clarity.

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181201-22217 EST

JFletcher:

If I compare heating the sane quantity of water in the hot pot with it in the microwave, and I adjust the power input to the hot pot, easy to do, to that of the microwave input, then because of the efficiency difference the microwave will take longer.

Is the microwave more convenient? Yes. Do I care about the energy cost difference? No. The cost to heat one cup of water is of no consequence in the big picture.

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