Which is cheaper: Boiling Hot Water or Cold?

Every morning I make coffee with a French Press and agonize over what is the cheapest way to boil about three cups of water.

Option A)

Run the hot water tap for 40 seconds until the water IS hot, and put it in the kettle where a small abount of gas is used to bring it to a boil.
Option B)

Run the same amount of water “Pipe-temperature” into the kettle which is basically cool, and wait longer for the water to reaching a boiling point.
Consider:

> Option A) wastes water, Option B) wastes gas

> I had to burn some gas in the first place to get the water hot in the H2O heater, but that’s FAR efficent at heating water compared to an open flame on my stove top.

I guess you need to know the cost of water and the cost of gas, how much water is wasted at the tap waiting for it to get hot, and how much faster hot water boils over cold water.

Do any generalizations indicate it costs a LOT more one way or the other?

What is cheaper? Wasting gas or water?

You also need to consider the whole pipe-ful of hot water between your tap and the heater now that you’ve got hot water coming out the tap; unless you have an immediate use for more hot water, all the gas spent heating it is going to be wasted.

My next house will have an insta-hot thingy in the kitchen sink.

I figured the water volume from the heater to sink for my mother’s house. It was about 13 gallons of water. The heaters in a stupid spot, moving back to where the old heater had been would save two thirds the volume of water to get hot at the tap. Your looking at multiple gallons compared to a quart or two of water. There’s no difference in efficiancy that would make running gallons of water cheaper.

My experience is that you should make your coffee with water out of the cold water spigot, since it’ll taste better — water from the hot water supply tends to have more dissolved crap in it.

But as far as a cost perspective goes, I don’t know the answer.

Cold water may taste better, but that may be because it has more air dissolved in it, not less. I don’t see how the water heater can add other solutes.

In winter, or when you are running your heater the best way would be to use the gas stove. Any waste heat would convert 100% to your home heat. Your water heater is vented and the pipes are run in places where the heat from them doesn’t really help.

In the summer a/c season I would tend towards letting the water run till hot to start, as the waste heat will have to be removed.

In times where you don’t need heat nor to remove the heat, I would say that starting with cold would be better, unless you can tap in to the hot water sooner, perhaps filling the pot in the shower instead (if you take a shower in the morning).

Also a much bigger factor is heat only the water you need.

Well, here in the Plankton household, we have two factors to consider:

A) Our water heater is gas, while the stove is electric, and
B) We don’t have to pay for our water

So I stick with the first option and let the tap run.

The reasoning I’ve always heard behind this is that more gunk from the pipes dissolves in the water on its way from the water heater to you. That said, I’ve never actually done a double-blind test comparing hot water that has been boiled & cooled versus cold water that has been boiled & cooled — it’s just one of those things that I’ve always done.

I haven’t heated water on the stove for years. The microwave is faster. It runs on 110 power for two minutes, where boiling water, hot or cold on the stove takes at least five minutes of 220 power.
I could be missing something…

I have heard that mircowavng the water it usually the most efficient way, not due to the method of heating, but due to usually people microwave just enough water that then need, on the stove they make much more, like 2x the amount.

I’ve read that cooking and such should be started with cold water, since the hot water piping (depending on your sitch) may have lead leaching from old pipes. I would never serve my child hot water from the tap. Stupid? Maybe.

Just a habit though now.

Do you guys not do the whole electric-kettle thing?

Actually, boiling hot water is something that can be done at normal one-atmosphere pressure, while it requires great amounts of energy to reduce the pressure in a closed vessel to the partial vacuum required for boiling water while it remains cold.

Oh

You’re right that it greatly depends on the situation. Most houses built after 1900 won’t have lead in the pipes, and many of the houses built before that have had all the plumbing replaced over the years because of natural corrosion.

The place where I work was built in the late 1820s and before the rennovations, it wasn’t just lead-soldered pipes that you had to worry you-- the pipes themselves were made from lead. It was one of the first things we told new employees: “Run the water for at least a minute before you use it to make coffee or tea.”

So you have cold diluted coffee. No thanks. :smack:

Iced Coffiee without watering it down with water.

:smack:

Iced Coffiee without watering it down with ice.