22 Dec. 1976|
Build wood fired hot tub heater,wooden kayak rack for truck,hand planers home depot - PDF Review
Well this year I wanted to try something different instead of using the pump to circulate water through the copper tubing method. It doesn't take but 3-4 splits of wood to keep this tube cooking every day to about 105-110 deg. No way to drop temp very quickly, just takes some getting used to how much wood to burn to gain the temp needed.
Yea Dianne All one needs is a sealed stainless steel container to build a fire around, or under in my case, and heat up the water without electricity. In this instructable I will describe how I built a hot tub for less than $100 NZ ($75ish USD) from an old bulk liquids tank, a gas bottle and some stainless tube and junk that I had laying around.
This tub is cheap and relatively easy to build and is also useful as a plunge pool in hot weather too. When the fire is going I can really feel the suction on the bottom hose in the tub, the theromosyphone works great.
Being that we have bonfires a lot, this would give us an option to do both using one heat source. This one won't be sealed so it will be critical as to the positioning of the barrel next to the tub.
Water circulates by the thermo-siphon effect: Cold water comes in the lower inlet, is heated in a jacket surrounding the firebox and flows through the top outlet into the tank. It also came with a pump, filter, electric heat (i'll still be using a fire) and a blower for free. In the winter, our little tank goes from nearly freezing water to a comfortable soaking temperature in less than one hour with just an armful of wood.
At the moment i have an old open fire place with a wet back system, but it is a poor conductor so i'm thinking of throwing an old all copper car radiator in its place.
I have not yet burned through it, but I do think that the steal tube might be better because there is a lot of residual rust and oil and other dirt in old radiators that doesn't seem to disappear.
And then in the heating system, toward the end of the pipe have some sort of removable filter to catch anything in the water from the metal reacting with your chemicals. While you want it to be cheam and effective, have to fix it repeatedly wouldn't work so, go with metal tubes. Thermosiphoning occurs due to the heat differential in the coil rather than the whole of the hot tub. When the heat source is cranking the water temp in the top of the coil will always be hotter than the water coming in the bottom - that's where the driving force comes from.