Quote:
Originally Posted by Christ
Um... this is a great idea... and I'm not sure how it compares, but my dad takes a shower at the same time every day... and he uses a timer to make sure that there is enough hot water to take his shower each day.
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Yep, the methods are pretty comparable. Electrics lose most heat through the tank, whereas natural gas loses it through the flue.
Of course, you should be aware that the carbon emissions of 3 units of natural gas energy is equal to around 1 unit of electric energy. The power plant isn't 100% efficient, nor are the transmission lines.
Quote:
Originally Posted by Ryland
Any idea how much gas it does use to do this?
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Since water heater companies aren't required to disclose how much the pilot light consumes, it's hard to say. I've seen estimates from 50-1000 Btu/hr. Since my stove also runs on natural gas (and the oven has a pilot light) it's hard to determine the water heater usage alone. Subjectively, it looks a little larger than my oven pilot light, which I'm guessing is on the low end. Ballpark figure, maybe 350 Btu/hr?
Including everything, most water heaters are around 60% efficient. A *lot* of that wasted heat goes out the flue. Even with the burner off, the pipe was warm to the touch. Now the temperature rise is only barely perceptible.
I've insulated the pipes (
hot and cold) to cut down on the cycling and losses. I went a little overboard, installing foam pipe sleeves (conductive loss) and then wrapped them with reflective mylar strips (radiative loss), securing it all with cable ties.
Since the water cools down a little after use, the average temperature of the water is lower which reduces standby losses. Taking these three improvements into account, I would say the efficiency has gone to between 80 and 90 percent.