Stock tank hot tub heater (material, transfer, sound, problem)

[roadrat]

Hello everyone, I have a plan to build a hot tub out of a stock tank and was considering several ways to heat the water.
My fuel of choice is wood, plentiful here in Maine, and I can source it for free.
This brings me to how to get the heat from the burning wood to the water (in a safe and efficient manner), I've seen pretty much every way to do this on the YouTube, from building a fire directly under a galvanized stock tank , to building a fire inside a coil of copper tubing, some use a pump, some rely on a thermosyphon.
One method that I caught only an image on Pinterest has piqued my interest, is a small wood stove with a large pot of boiling water on top, inside the water was a coil of copper that I'm assuming went to the hot tub.
I like this idea because it keeps the coil out of the flames, avoiding problems like heavy soot build up, and damage to the copper from the direct flame.
Does this sound feasible? Do you think the water temp of 212F would transfer enough heat through the coil?
What about changing the coil to high temp silicone tubing?

Any help would be greatly appreciated!

[harry chickpea]

Highly inefficient. It is fairly easy to check out the BTU output of burners on stoves. That is the first limitation to how much can be transferred. Then there are the losses and insulative values in the materials used to get from stove to tub. Such a setup might keep a tub that is already hot from cooling off too quickly.

[rabbit33]

It's almost certain that what you rig up will be far less efficient than something a commercial outfit has had actual engineers with expertise in burner design, heat transfer, etc. design.

Are you talking about using a galvanized steel tank for a hot tub? Sounds like a terrible idea, especially in a cool climate. Hot tubs work by having tons of insulation around the water so temperature swings are minimized.

You also need to set up a filtration and water treatment arrangement unless you want to have massive algae buildup and give yourself and your guests a variety of interesting and persistent skin diseases. (Not to mention Legionnaire's.)

[roadrat]

Originally Posted by rabbit33

It's almost certain that what you rig up will be far less efficient than something a commercial outfit has had actual engineers with expertise in burner design, heat transfer, etc. design.

Are you talking about using a galvanized steel tank for a hot tub? Sounds like a terrible idea, especially in a cool climate. Hot tubs work by having tons of insulation around the water so temperature swings are minimized.

You also need to set up a filtration and water treatment arrangement unless you want to have massive algae buildup and give yourself and your guests a variety of interesting and persistent skin diseases. (Not to mention Legionnaire's.)

Either galvanized or plastic, haven't decided yet,. and yes I will add some type of insulation. as far as filtration most of these set ups are pretty small so a chlorine puck floater and regular water changes will surfiest.
This is not a new concept, people have been using stock tanks as hot tubs and small pools for decades.