How to heat a wood hot tub with fire (So it actually gets HOT!) - Hot tub Build Part 2
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- Опубликовано: 25 май 2022
- The copper coil wasn't cutting it to heat my 1000 gallon wood hot tub. I come up and build with a water heater wood fired boiler system using a 5 gallon jerry can.
#DIYhottub #woodjacuzzi #Fireheated 
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You need more coils of copper tube in the fire pit. The more the better and touching each other tightly. To create this new coil wrap them around a circular object of the desired size. (If you try to do this free hand you will not get optimal results.) This will give the water more time to heat up before it is released back into the hot tub by the pump. Thanks.
Yeah there is definitely a science to the copper coils. I think a little larger tube diameter and about twice as many coils could help a lot
@@DIYSCOTT smaller pipe and more of it. which gives more surface area for heat to touch.. also 5:03 is wrong you want it moving fast to absorb heat fast and add to water. Also you called your filter "cotton balls" they're called "filterballs" and they are polyester.. but you should know that you need to clean them every year or so and you can rinse it out in sinks or even wash them in laundry machine etc. They work about the same as sand but are cheaper / easier on pumps / can last longer / don't have to backflush as often
@@gg-gn3re Interesting... Yeah I washed the filterballs in the washing machine and they came out brand new looking
@@DIYSCOTT yea the filterballs can last a very long time. Pretty cool technology. With the fast moving water it's simple physics, the colder the water is, the more heat will thermal transfer from pipe and bring into the tub. the overall mass of water will heat up faster but you won't notice the water being "way hotter" than when it goes in the inlet. big mistake people make. good luck
@@DIYSCOTTdon't listen to the guy who suggested smaller diameter pipe with more coils. That would get the water too hot causing boiling which is NOT what you want when building a thermocycling tub heater. The boiling causes air in the line which reduces the thermocycling action (greatly reduces the flow). What you need is a larger diameter pipe with only about 5-10 coils to achieve efficient thermocycling. The larger diameter allows the water to stay cool enough so that it's not boiling by the time it gets to the top. Hope that helps
@DIYSCOTT don't listen to the guy who suggested smaller diameter pipe with more coils. That would get the water too hot causing boiling which is NOT what you want when building a thermocycling tub heater. The boiling causes air in the line which reduces the thermocycling action (greatly reduces the flow). What you need is a larger diameter pipe with only about 5-10 coils to achieve efficient thermocycling. The larger diameter allows the water to stay cool enough so that it's not boiling by the time it gets to the top. Hope that helps
Nice job.
Thanks Murray!
04:09 When you've never used an angle grinder before
Been 6 months probably been said haha... you should build that fireplace better as in concrete it together and bring the bricks up above the tank as well then add a chimney, nothing special just raise the sides and front, build it so you can only access from underneath (so the fuel can is walled in) then add concrete (in the cinder blocks pack em with dirt to save on concrete and get heat mass). this will then drag more heat up and passed the can in a more direct way so youre not wasting that energy, also a chimney will drag more heat upwards through convection as well as the smoke up above ya heads while in the tub rather than ya face occasionally haha
There are wood fired water heaters that work very efficiently. Friends had one in their home without power.
Yeah I looked at those a little bit. Could be a great solution depending on the price. Thanks!
Yeah there are thousands of these in Finland and none of them have a pump. Been to loads of them and they work great. Never built one but I am sure you can find diagrams. It's called a "Palju" here
Modify a propane tank for the boiler. Can cut top out to place bulkheads on the inlet and outlet. Then weld the top back on.
Definitely want a pressure relief valve of some sort too so you don't accidentally create a bomb. Retrofitting propane tanks also sketches me out cause you need to be 1000% sure there is nothing left in it before cutting into it lol
Did you build the tub yourself? If so do you have a video? Looks great
Yes sir: ruclips.net/video/5M__nHYCPrg/видео.html
How many hours did it take to heat? I have an 8ft stock tank I’ve turned into a pool and I’m trying to heat it for winter. I have a rocket stove with copper pipe in it and it heats there water coming out to 160° but it used too much fuel because it burns so quickly. I was thinking about adding a water tank above it as well just like you’ve done to accelerate the process.
Maybe like 4 hours... I got up to around 93-95 degrees. Definitely need whatever you are trying to heat to be more in the fire than I have it for efficiency. Also a legit insulated cover would help
You can make a duL.fuel, propane and rocket. Just to get it up.tonheat.
Curious about the overall price you've spent on this. Obviously, not everything is based around price, as this is probably more of a passion project than the "im going to get a hottub for cheap" build, but I have a feeling that the overall cost of all the materials and time, you could have just bought a small infaltable hot tub and used the pump/heater from one of them.... WITH THAT SAID. I see unexpected potential with the current build concept. Weld a flatbox water tank together and place above the fire (You want the hot water to go to the bottom near your feet vs the top, it will heat up some much quick).Then Use the space ontop of the welded box for a pizza brick oven. I would also build drink holders for the hot tub.
I never added it all up but probably around $1400-$1600. Interesting on the hot water output location. Is that just so it mixes better as it rises and doesn't evaporate as much? I love the other ideas too!
Nice idea, however the pvc pipes behind furnace are gonna melt at somepoint add some form of heat shrink
Yeah I thought they would too. They don't even get warm somehow but I will try to them protected
First thing I thought as well, like bruh... that pvc is too close to the pit. Lol
@@eds6569 Yeah I worried about this a lot but surprisingly it never got even warm to the touch
To make the heating tank more efficient, insulate the sides and top of with a sand and cement mix concrete.?
Yeah maximizing heat transfer and efficiency is key
I would put a pressure release valve on that water tank just for safety. You would be surprised how powerful trapped water turning to steam is.
Yeah I thought about that. Since the outlet pipe can't be shut off I figured it would be okay but always better safe than sorry!
He already has one built in with the spring loaded cap.
@@tinker0000 I don't know if the cap or the tank would fail first. But either way I think its relatively safe since the outlet pipe can't be shut off
Rather than a jerry can I would have gone with a radiator, either from a house or a car. They are designed to transfer heat from water to air, I assume they would work in reverse.
Yeah just don’t think I could expose it directly to the fire. Maybe an enclosed fire place and put a radiator in the chimney?
Where I bought the pump: www.amazon.com/dp/B088T67SQX?psc=1&ref=ppx_yo2ov_dt_b_product_details
if you stuck with wood fire idea then you need more copper and fire enclosure like old bbq grill. you have too much heat escaping. I would do 50 ft of 1/2 or even 3/4 inch copper coil or more( with right set up temperature wont be an issue but flow will be, so using bigger pipe helps.
google what rocket stove is, and apply same idea. open fire pit wont do much.
I did same thing, with brick fire pit stricture and top cover, so fire was going of the sides like rocket stove. with 1/2 - 50 ft long pipe water was near boiling temp. took about 3-4 hours to heat 1000gal tub
also if you planning to use hut tub a lot, I would suggest switching to electric.
Yeah getting the right tubing is definetly an art. Thanks for the tips!
Could have looked for very old (cheap) scuba gear as a tank, since it would be safe and all-stainless steel it should be safe AF and you can weld to it
Smart yeah better then burning off paint
Looks great! Did you fix the massive leak in your tub?
No he didn’t. My room is flooded. I’ve lost everything. I can’t bring guys to my room anymore. DO NOT TRUST THIS MAN!
Hahaha
My legal team will reach out to you! "To recover punitive damages, a plaintiff will usually have to show that a defendant published a defamatory statement(s) with actual malice or with reckless disregard as to its truthfulness." - A smart man
@@DIYSCOTT just come to my room tonight to make it all right ;)
Seems pretty inefficient since most of the heat is not touching the heating element. Coil designs have a much higher surface where the flames hit the water.
Yeah I think more coils closer to the bottom of the fire would help
propane would work np, and very effectively
Yeah like a propane water heater?
All you needed in the first place was more coils dude.
You need to use a rocket stove.
You can buy a 5.5kw heater online for about $150.
Yeah i thought about some sort of electric water heater which could've helped for sure
rocket stove with thermo symphyn
Yeah I realized trying to maximize efficiency was the most important thing so I switched to a 55 gallon drum to contain more of the heat
you didn't use anywhere near enough copper tubing in your coil! the whole fire pit should be lined top to bottom with the coil for a hot tub that size!!! The pump isn't needed.
Skip the bull shit,
get 2000w of solar, and a heating element with a pump.
You had one bad ide and now you came with the new one bad idea😂😂😂✌️ peace man i don”t have money now to build myne but soon iwill make it i will teach u some cheats to make it cheaper and use less wood
Hahaha I just watched this which might help: ruclips.net/video/c1amhcRwTyM/видео.html
After several attempts and researching more I realized I needed more ways to efficiently transfer the heat. If you watch the third video I made I put the fire in a 55 gallon drum and I think if you had another drum just a little bit smaller and put it inside of the drum as a fire drum then had water in between them that would maximize surface area and heat transfer. The whole thing was just an experiment and fun for me but I think a good system could work well if you make a good plan from the beginning. Good luck :)
Lol you definitely don’t want to weld on a used gas can
you need about 5 times as many coils on your copper pipes... that's why its taking so long to heat up! The water needs more time to travel through the pipes and heat up. your first design was perfect it just needed more pipe.
Got it. I'm thinking about doing one more version with more coils like you said and in some sort of more contained way to minimize heat loss
11:34 That's how to burn your house down,🙄
Lol. I had 1000 gallons of H20 and a fire extinguisher on standby. (Being serious I kept an eye on the fire at all times and was cautious, the video is supposed to make it look a little more out-of-hand and fun) This project was an experiment and supposed to be fun. Hopefully entertaining for you to watch and serve as a baseline to learn from for people who maybe want to try something similar.
i'm sorry but you should find someone with some trade related experience when attempting a project like this or don't show all of your mistakes. I have a 15' above ground pool that i heat with wood. I used a 45 gallon drum with 50' of 1/2" copper tubing in the top half of the barrel and the fire on the bottom. I put two doors on the side, one for access to feed wood and one to clean out ash bellow the grate and to act as a vent door. A hole was cut in the top where a chimney was placed. I could move the temperature in the pool 2 degrees an hour. I live in northern B.C. Canada and the water starts at 50 degrees when i fill the pool.
Not many people my age where I'm from know the difference between a 2x4 and a sheet of plywood so it's hard to find good help haha. I definitely learned a good amount from this project: why I do most of my projects. I started to catch on to the 55 gallon drum idea (in the third video) to maximize heat transfer and be as efficient as possible) but I honestly just didn't have enough room or money to keep going on it. Glad yours works well.
You could also get two Jerry cans just connect em both dummy