General Question

elbanditoroso's avatar

Which takes less energy?

Asked by elbanditoroso (30572points) February 11th, 2018

All electric home – gas oven is not an option.

I want to get water in a 4-quart saucepan to a boil.

Time is not a factor.


1) take tap water (at room temp), fill the saucepan, put it on the stove top, turn the burner on high. (takes longer on stove top)

2) run tap water until it is hot (from the water heater), fill the saucepan, then put on stove top,turn the burner on high. (Shorter on stove top, but longer wait for tap water to get hot; wastes the cool water)

My gut feeling is that option 1 is more fuel efficient.

I imagine to prove the case I would need to calculate the power draw of the water heater for some period of time and compare that to the power draw of the electric element of the stove.

Any ideas?

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8 Answers

canidmajor's avatar

Send this Q to LuckyGuy!

ragingloli's avatar

Option 2 might be more efficient.
The water heater might be better insulated, thus more heat gets used to heat the water, and not radiated out to the environment.

zenvelo's avatar

The water in the heater is going to be heated whether you use it or not.

You can have the BTU’s applied in the water heater or on the stove, but the same number are needed to get it to boil.

But if you have 2lbs of water in the pan, and raise it from 45 to 110 in the sauce pan and then from 110 to 212, the water heater is still raising water from 45 to 110 if you use it or not.

So better to use water hot from the tap to fill your sauce pan.

(In California, though, you would be more likely to save the water from the tap before it heats up, or else just heat water on the stove so as to not waste water . We are in a drought.)

kritiper's avatar

I believe the power usage would be the same. Any water used from the water heater will still have to be reheated when it is replaced inside the tank, which happens automatically.

CWOTUS's avatar

Assuming you’re attempting to heat four quarts of water, total:

Put two quarts of room temperature water in the pan on the stove at high setting.

Put another two quarts into a properly-sized and loosely covered microwavable container, and heat that water on high for about five minutes. When the microwave cycle is complete, pour that water into the pan on the stove and bring the entire quantity to a boil.

Depending on the mix, you may want to heat more or less water in the microwave or adjust the time higher or lower. (Obviously, if the microwave water boils at, say, four minutes, there’s no need to keep running that.)

johnpowell's avatar

I think it would probably be about a wash unless you put the tap water outside to warm it up. If you have the heater in your dwelling on it will pull in heat from the air to warm the water which will make your heater turn on for a second later. I just put my hand on the hot water heater here. It is pretty hot. So some of that heat from heating the water is leaking out into my apartment so my heater works less.

And yeah… Please don’t use hot water from the hot water heater for cooking. A few years ago our hot water heater exploded and lets just say that after seeing the inside of it I would never put that water in my body.

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