Author Topic: Converting barrel stove into a water heater?  (Read 3401 times)

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Bullony13

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Converting barrel stove into a water heater?
« on: February 06, 2005, 06:47:24 AM »
I have an electrically heated hot tub, and as you can imagine, it really sucks down the kilowatts. I have an old barrel stove (like this: http://www.northerntool.com/webapp/wcs/stores/servlet/
ProductDisplay?storeId=6970&productId=2089



4&R=20894) that I'd like to use to heat the water.


What do you think the best way to heat water with that would be? I'm thinking some 1/2" copper pipe run lengthwise inside the top of the barrel, anyone have a better idea? How much wood do you think it would take to heat the 500 gallon tub from about 50 degrees to around 100 degrees?

« Last Edit: February 06, 2005, 06:47:24 AM by (unknown) »

picmacmillan

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Re: Converting barrel stove into a water heater?
« Reply #1 on: February 06, 2005, 01:59:28 PM »
a btu(british thermal unit), is the amount of heat energy it takes to raise the temperature of 1 pound of water by 1 degree farenheit.

  1 btu = 1054.8 joules...

 if you want to raise the temperature 50 degrees,i don't know how much water is in your tub but i will use a smaller example and you can substitute the numbers later......

 a tea kettle holds 2 pounds of water...

 lets say at room temperature (68degrees farenheit)...not counting the radiant heat losses etc to the kettle....

 the following should be the result 2x(212-68)=288 btu...and thats for a kettle,your tub is exponentially larger and i don't have the stats in front of me for the specific heat capacity of wood..i know paper burns at 451 degrees farenheit(hence the movie farenheit 451)....i don't remember what water weighs but i think it is 5 pounds per gallon or somthing like that...figure out how many gallons of water you have in the tub, calculate it's weight,use the above formula to give you how many btu's, then light wood stove...

it isn't really how much wood you need, it's how many btu's and for how long...oh and by the way....

 it takes 288 btu's x 1054.8 joules =303,780 joules of energy just for a kettle...no matter if it takes a while to heat that much water for your tub by wood heat,it makes far better sense to use wood and save the electricity like you said in your post......good luck....pickster
« Last Edit: February 06, 2005, 01:59:28 PM by picmacmillan »

pyrocasto

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Re: Converting barrel stove into a water heater?
« Reply #2 on: February 06, 2005, 09:19:26 PM »
My guess would be what you said, and run some tubing through and heat it that way, unless you can figure out a way to submerge the stove. ;)  My hot tub takes abou 6 hours on electricity to go from 50 to 100, though I would hope that fire would heat it faster, I dont know.


According to that formula, it would take 266,000 btu's to heat my hot tub of 350 gallons. O_O

« Last Edit: February 06, 2005, 09:19:26 PM by pyrocasto »