Fire Hot Tub





Introduction: Fire Hot Tub

i was in search for a hot tub system where 1000 liter of water was ready in about an hour instead of 3 or 4 hours like most projects i've seen..

also it needs to be a camp fire to sit around with a drink or maybe grill some meat untill the water is warm

i still had in memory how hot camp fires got after placing wood above wood causing massive flames

this all combined is what i came up with..

Step 1: Buiding the Fire Cage

this fire cage is build like a camp fire so it can hold long sticks in place and is feeded trough the top ring

the water will be pumped in the bottom ring and then trough the thin tubes to the top ring

from here it will be led to the tub again

Step 2: Filled the Cage With Water for Testing (three Little Holes)..

Step 3: Time to Clean the Test Tub

Step 4: A Pond Pump Is Used With Rubber Hoses From a Radiator

Step 5: Everything Mounted and in Position!!

Step 6: Time to Lit the Fire!!

Step 7: Within Minutes the Flames Are Bursting Out at the Top Creating Massive Heat

Step 8: After Just One Hour the Water Temperature Reaches 40 Gr. Celcius

Step 9: Next Morning, the Water Still Has 30 Gr. Celcius

Step 10: This Thing Did an Awesome Job, Time to Make It for Real!!



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    If you use plastic tubes it should work in theory, because the plastic isn't gonna burn since it's colled by the water

    yeah, but there is a little problem with money, space and time ;-) but we will get there..

    yeah doesnt mean yes in this context :-)

    Clever idea!

    Using stainless tubing would be trick and the most durable of course. The trade off is cost and welding. Unless you weld and get a deal on materials of course.

    Here's a suggestion that would reduce come welding. Find a muffler shop and have them bend some exhaust pipe into a circle. From what I see in your pictures I can see that you can fabricate and weld.

    The concern about rusting or burning out sure wouldn't bother me. As long as the manifolds are full of water they won't get too hot. When you're done heating the tub, disconnect, drain the heater and leave a small fire inside to warm/evaporate the unit.

    Using a heat exchanger adds complexity for something that is likely not to be used a lot. I would consider adding a thermal switch of some kind to control the pump. You might be building a lobster pot hahaha! that people are going to be able to always pay attention to the heated water temp.

    I'm looking forward to the full size build.


    1 reply

    a stainless steel fire cage will cost me about 500 euro for the tubing here in belgium, the welding i can do myself, i have taken a look at muffler parts, they don't go very sheap as well.. the positive thing about the parts is the super thin wall thickness so the water will heat up quicker..

    the Final Cage Will be made in stainless steel, copper would be better but the welded joints would not hold this kind of temperatures i think..

    I love this idea. Will the heat affect the life expectancy of the pond pump?

    1 reply

    connect the pump so it pushes cold water from the tub instead of pulling hot water from the fireplace

    Normally you dont need a pump, the heat will pump naturally the water. As well it would be better to use copper tubing to avoid corrosion

    1 reply

    you're right, but for safety reasons i put a pump so the water doesnt get so Hot when entering the tub..

    please share a buildlog of the real deal