Help me calculate $Heating H2O

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Jim Karr

Well-Known Member
Dec 26, 2005
Reaction score
SW Michigan..Bangor/Covert area
I'm trying to figure out what the cheapest way to heat my water in the HLT.

If I use my 60K LP burner (NB 7334) to heat 15 gallons of 56*F water, my costs for LP are about 6 cents a pound.

To raise the water temp to 175*F, what would my LP consumption be?

According to the table on, if one uses water heater elements in the HLT, raising the temp of 15 gallons from 70 to 160 takes 36 minutes.

If I want to start at 60, end up at 170, that's an increase of 20 additional degrees. That would be an increase of roughly 22 percent.

Using a 6000watt element, this increased time would be about 44 minutes total. At 6.3 cents per KWH, (6KW x 6.3 cents x .75 hours) electrical costs would be less than 30 cents! Am I calculating this correctly?

I can't imagine that using a burner would come anywhere close to this cost.

Any thoughts/concerns/obvious mistakes?
I roughed out a basic breakdown based on averages at one time:
[QUOTE="5 Is Not Enough]At about $.10/kwh, a 2 hr usage would cost me about $1.80 vs. (guessing) 180,000BTU's(~2gal/hour) @ average of $2.50/gal would be about $5.00.[/QUOTE]
The difficulty comes in the fact of the efficiency you can achieve. The effective BTUs are different than the output btus...
Heat loss is going to be such a huge variable between setups, it's going to be tough to say. Have you timed how long it takes you to heat your water? At the 21,548 BTU/lb listed in your link, you'll be using ~2.7845 lb/hr with your 60K BTU/hr burner. It should be pretty straight forward to calculate.
So if my burner uses 60k in an hour, and it takes 2 hours to bring the water to 170*F, I have used a total of 120,000btu.

Dividing by ~20,000 gives me about 6 pounds of LP gas.....6 cents a pound, 36cents total for gas.

Not much difference between electric heating and LP.....Electric may be a bit quicker, and a bit more convenient in that you can switch it on and walk away!

Thanks for your help!:ban: