Water pre heater for hot tub

[Frankievalli]

Hello all.
Thanks for letting me join.

I am a novice looking to create a home made water heater from a rock type stove.
The idea is to be able to preheat the mains water coming into my hot tub when I flush it out and refill it ideally I’d like to get the water up to about 30° using firewood I’m thinking of a K type rocket stove with coil in the exhaust flue.
Any ideas or advice on what material to use for the coil and what single phase welder might be good for a novice.

 

[julianf]

If you dont care what it looks like, maybe consider -

Pick up an old oil fired boiler. They can be had for pocket change. Use the water jacket only.

Route the exhaust from your stove though the oil boiler water jacket. You would probably need to elevate the water jacket.

Oil boilers are so cheap second hand, and it will be about a million times better at extracting heat than a coil.

You would, however, need a secondary loop - if you pump the water though the water jacket directly, you will have a very rusty looking hot tub, i expect.

 

[gaz1]

apostal did the the rocket stove shower no coil needed as it uses tubing and a hot plate on the top

copper pipe will melt inside a rocket stove

this is what happens with them with a coil

now a snorkal stove in a way is a rocket stove now id advise going this way and pump from an external tub into the main tube

 

[gaz1]

kelly kettle water heater same as a rocket stove

the issue stands its great getting that water hot efficent enough the issue is no control when the water is hot it cannot be slowed down whilst the snorkal stove can be controled

 

[Erie Fred]

Put the wood stove inside the hot tub......

 

[roofman]

Just have a spit shine with a wet 6" square flannel, spend the money saved on Vodka and midget jems made by Lions only though...seriously a coil from a hot pressure washer would be perfect. welcome to the forum too Frankie