Portable water heater!

moored4 · Apr 20, 2011

We are setting up a hot tub inside a wilderness area on private property. We are cutting the oak barrel stays and the steel ring to keep it all together pre assembling it and then we will disassemble it all, cause everything has to be carried in 20+ miles on horse and mule back.
We need ideals on how to heat 12 to 1500 gallons of mountain spring water in a reasonable time period (1 hour or so) using wood.
Thanks for all of the Good ideals inadvance.:thumbsup:

Slacker · Apr 20, 2011

Do you have a way to run a small pump to fill a water heater tank? I'm thinking a 3/8" copper coil on the stove running to a hot water heater tank placed higher than the coil. Hot water rises, cold water sinks. Be sure the water heater has a pressure release valve that works, don't want to make a bomb.

bearcreek paul · Apr 20, 2011

You should checkout Hilkoil here is a link to the website.http://www.hilkoil.com/

Kays Supply · Apr 20, 2011

You better be doing some math. You are talking some serious BTUs to get that much water hot that fast. It will take a while to get the fire going big enough to heat that much water. It will take a pretty good size coil also to transfer the heat that fast.

jdonovan · Apr 20, 2011

moored4 said:
We need ideals on how to heat 12 to 1500 gallons of mountain spring water in a reasonable time period (1 hour or so) using wood.

BTU = energy required to heat 1lb of water 1 degree F.
1500 Gallons x 8.3 lbs = 12,450 lbs

Lets assume you have cold mountain spring water at 50 and need to get it to 100F for the spa.

Increase temp by 50 degrees.

You need to put +/- 625,000 BTU's into the water.

A REALLY big heat your house kind of wood stove is in the 80-100K BTU range... and You could never capture 100% of the wood stove's heat, and the water is giving off heat to the air as you are trying to heat it up...

So either you will need enough wood burning that the Russians would mistake it for an ICBM launch, or you need to adjust your time to heat, or heat fewer gallons.

The way we did it back in the day, was a few old 500 Gal propane tanks cut in half. The closed end of the tank had a smoke stack cut/welded into it, and the big open end was outside the tub.

We then built a BIG fire inside the tanks and it still took about a day to heat the tub up, but we were dealing with a 30' wide, 4' deep tub. Once it got up to temp we could cut back on the number and intensity of the fires, but it took a lot of wood and a lot of time to get the water heated up.

RobertN · Apr 20, 2011

There are a couple companies that make that sort of heater.

Island Hot Tub Company/Chofu Heaters - Wood-Fired Chofu Heater
How to build a wood fired hot tub
The Snorkel® and Scuba® Stoves
Google

grsthegreat · Apr 20, 2011

1500 gal is a HUGE hot tub. my 8 man tub only takes 500 gallons. You must like to party......

moored4 · Apr 20, 2011

moored4 said:
We are setting up a hot tub inside a wilderness area on private property. We are cutting the oak barrel stays and the steel ring to keep it all together pre assembling it and then we will disassemble it all, cause everything has to be carried in 20+ miles on horse and mule back.
We need ideals on how to heat 12 to 1500 gallons of mountain spring water in a reasonable time period (1 hour or so) using wood.
Thanks for all of the Good ideals inadvance.:thumbsup:

I Redid the math and it's 1200 gallons. The time is not an exact number, we just want hot water so our visitors can rest and soak after ridding horse and rafting all day. The camp cook can start the fire sometime during the day! The system has to be portable by horse back and we have no electrical power to use for it! Lots a squaw wood around!

PS: Want to keep it as cheap as we can also cause during the winter who knows what could happen to it!

Taylortractornut · Apr 20, 2011

I built a fire box one time that fit over in the side of a hot tub. It was a top fill and to get the air at the fire I bent a steel pipe and weded it in the bottom of my fire box. THe flue was on the side of the box at the top. It worked good but was a pain to scoop out the ashes from the top. The outside was stipped with wood to avoid contact to skin.

I have a water heater I made from a 55 gallon drum with a 3 inch exhaust pipe welded all the way through it. I welded a fitting on the bottom and one on the top to accept garden hose and other fittings. I have a T&P valve on the top. THe pipe extends 4 inches out each end of the 55 gallon drum. I have a half a steel 55 gallon drum that I burnt a 3 inch hole in the top. The pipe will fit in it and and I build a fire in the bottom tank and it will heat up pretty fast. Ive used this a few times when the Gas water heater broke and during other emergencies.