Wood heated hotttub

So I have built a cedar hot tub and a built a stainless steel stove to heat the water. I have 2” space between the walls of the stove where the water will be. Iam wondering where to put the ports in the hot tub, like how far apart is most efficient? How close to top of water? Here are a few pics of my build. All comments and advice welcomed. Also did anyone build a tub and hook up a pump for jets?

What a beautiful looking hot tub! Well done.

I'm interested in learning the answer to this too. I hope another forum member has some experience or knows some theory. I have an old cast iron bath and that I would like to set up, outside, and wood fire.

That hot tub is gorgeous and the stove isn't shabby either.

Congratulations on the builds!

very nice build!

Awesome build. On our lazily purchased Chofu stove to and cedar tub, this is the layout:
As I remember, the main keys were having downflow for the lower Tub->Stove line, and an incline for the Stove->Tub line (with the hot water rising). Some flexibility can be had with placement of the stove (on blocks or on a lower surface than tub). I think our layout was around the middle of the suggested parameters for pitch, so if you are close it will probably work fine. Found a picture of the layout suggested:


Congratulations though, this is probably the best luxury I can imagine having! I also like how we can use pitchier soft wood from wildfire fuels thinning that I would not use in our house wood stove due to creosote and chimney fire concerns in the house that I do not have outside under the stars.

Thanks so much Ben Zumeta! Thanks exactly what I wanted to see and read. How far is your top “Hotwater “ outlet below the surface of your water? What would you guess is the distance between the two outlets coming into your tub?

It is important that the hot water inlet is never exposed above the water line while heating, as it could come out scalding hot. We fill to about 1” above the inlet, as any higher and the tub will overflow with two people in it. I can’t think of an easier way to measure one’s displacement volume than to fill the tub and get as many people as the max you plan in to have in it. Whatever spills out will be your displacement, and what is left will be the highest you can fill the tub for that volume of humanity. Then I’d put the hot water inlet an inch or so below that water line, and adjust the heater stove height to allow for the minimum slope mentioned above (2”/ft).

I bet if you reached out to some of the smaller companies that make the tubs and heaters, they’d be impressed by your DIY work and offer their advice on this aspect.

Right on.. thanks again Ben Zumeta ….So in my tub every inch is 45 litres. According to google every kg of body is equal to 1 litre. Iam 85 ish and wife is 65 ish. So 150 kg. So 150 litres ,so should raise water less than 3 inches.  So tub is 39 “ high, will fill to 32, put my hot outlet at 31. Cold inlet at 6”?? What you think ? Anyone? Also did anyone ever put water jets in their DIY tubs?? I was gonna put air jets but someone said air just cools the water, better to use water!