Mof Posted December 28, 2015 Share Posted December 28, 2015 Credit to Rumrum for the idea So I was considering getting a spa, but they're so damn expensive And I'm so damn cheap So I made this Then started on the heating Scored a flue from the Father-in-law and made a choke for it And welded the flue to the drum...uh firebox Old gas bottle for the water, spacers welded to the sides to keep it in the middle And mounted Rebar fire grate Hooked up So it turns out gas bottles have a coating on the inside, which flakes off and fills my tub with crap. The top pipe had some holes in it so I welded them shut. But the weld in the inside caught some of the crap and blocked the pipe OH CRAP! I noticed the lower pipe was getting a bit warm, the top pipe was fucking hot, and the hot water had stopped going into the tub. so woops put the fire out quick. Cleared the block and god damn the water was hot! Also it's not so good at heating. So, I'm going to scrap the bottle and back to the drawing board. So far the cost, about $30ish ha 9 Quote Link to comment Share on other sites More sharing options...
NickJ Posted December 28, 2015 Share Posted December 28, 2015 Much awesomes! need more surface area huh, could you drill holes in the gas bottle and weld in some pipe length ways? How much room do these have? could a few people partake or is it a solo kinda deal? just built a bench seat out of some large pallets but this has me thinking one is a good idea for winter! Quote Link to comment Share on other sites More sharing options...
Mof Posted December 28, 2015 Author Share Posted December 28, 2015 You could comfortably get two in sitting down at either end. Standard sitting would put the water level about shoulder/neck height. I am going to build a couple of seats encasing cinder blocks or something, to make them sink. Current thought is i might have to fork out for some copper pipe. 15mm 5m long thin wall kinda thing. Standard for gas/plumbing suppliers? And make it into a coil and replace the bottle with it At least it won't introduce rust into the tub Quote Link to comment Share on other sites More sharing options...
Mof Posted December 28, 2015 Author Share Posted December 28, 2015 Hey Nick do you mean to get hot air up through the bottle? It does seem to get plenty hot, just very slow throughput Also some insulation around the tub might help, so I'm on the lookout for some thin polystyrene sheet Quote Link to comment Share on other sites More sharing options...
Mof Posted December 28, 2015 Author Share Posted December 28, 2015 Made a cover Quote Link to comment Share on other sites More sharing options...
BigT105e Posted December 28, 2015 Share Posted December 28, 2015 Hey mate, this is choice btw. If your gonna use copper tube for a coil, I have seen this done on the tube, the guy plugged one end by shoving soap/wax up its date, filled with H2o then plugged the other end in the same manner, chucked in a big freezer and as h2o froze and expanded the plugs popped out so tube didnt split, then he could bend tube around a 4" steel tube without the tube kinking, just an idea, worked well tho and cheap. Keep up the good work, might have to have a go myself... 1 Quote Link to comment Share on other sites More sharing options...
MaxPower Posted December 28, 2015 Share Posted December 28, 2015 hey mate I'm a plumber by trade and we normally have the pipes rising from the heat source to the storage unit, not sure if it really matters,not telling you what to do,looks cool wish i had the time to build one and find some gurls. Quote Link to comment Share on other sites More sharing options...
Mof Posted December 28, 2015 Author Share Posted December 28, 2015 I'm not quite following The cold water falls to the bottom of the tub, then it goes into the bottom of the gas bottle, it heats and rises, then goes into the top of the tub. Thermal convection/syphon something or other It's just the setup I made with shit I had lying around isn't very good and I'm thinking copper pipe coil would flow more, faster Quote Link to comment Share on other sites More sharing options...
fletch Posted December 28, 2015 Share Posted December 28, 2015 Yeah a coil would have more surface area for less volume of water. This will put more temperature into the water in the coil creating faster flow, which means more heat transfer per hour into your tub. Make your coil 20mm or 25mm if possible. 15mm will have too much internal restriction for a thermosyphon 2 Quote Link to comment Share on other sites More sharing options...
youwontgetpartsforitmate Posted December 28, 2015 Share Posted December 28, 2015 what fletch said. talk to a fridgy guy for the copper. http://www.refspecs.co.nz/product_info.php?cPath=82_84&products_id=593 1 Quote Link to comment Share on other sites More sharing options...
NickJ Posted December 28, 2015 Share Posted December 28, 2015 Hey Nick do you mean to get hot air up through the bottle? It does seem to get plenty hot, just very slow throughput Also some insulation around the tub might help, so I'm on the lookout for some thin polystyrene sheet Ah righto, sounds like the convection is having a hard time forcing a flow through the bottle, a coil seems to be the way to go Quote Link to comment Share on other sites More sharing options...
myk00l Posted January 2, 2016 Share Posted January 2, 2016 Quote Link to comment Share on other sites More sharing options...
johnny.race Posted January 4, 2016 Share Posted January 4, 2016 Yeah a coil would have more surface area for less volume of water. This will put more temperature into the water in the coil creating faster flow, which means more heat transfer per hour into your tub. Make your coil 20mm or 25mm if possible. 15mm will have too much internal restriction for a thermosyphon This is what i reckon too - go for bigger pipe. I have been experimenting with my waste oil burner using 20mm copper pipe. What an absolute cunt to try and coil at a smallish diameter though, lol. Made even worse by my propensity to be joining short bits together (expanded end/silphos) to get some length using scrap offcuts. But this is what I discovered ... there must be a point where the weight of the water (due to volume) is great enuff to prevent thermo siphoning to occur to any great degree, thus necessitating less volume (shorter length of pipe in the coil) or a pump. Another thing I have noticed is that most (all) of the wetbacks I have pulled from out of decommissioned fireboxes have been made from short lengths of large diameter copper pipe. They'd be at a guess around the 25mm OD size and say between 1 - 1.5m long. Just saying what i have seen and have tried. Good luck. Quote Link to comment Share on other sites More sharing options...
Mof Posted January 4, 2016 Author Share Posted January 4, 2016 Thanks for the info I was going to go for 20mm copper Filling it with sand helps keep its shape when coiling I believe. Have you actually done any experiments with length, and any thoughts on what is best? Quote Link to comment Share on other sites More sharing options...
downtrail Posted January 5, 2016 Share Posted January 5, 2016 How about building somethong like a shot gun condenser but use it to heat instead. Its basically lots of bits of copper pipe soldered into 2 end plates with a jacket around them to pump the water through like a heat exchanger type deal. Instead of your alcohol vapor going through it set it in a fire and pump water around the jacket. Quote Link to comment Share on other sites More sharing options...
Mof Posted January 5, 2016 Author Share Posted January 5, 2016 Ha, you basically just described a steam boiler. Quote Link to comment Share on other sites More sharing options...
mattscort Posted January 5, 2016 Share Posted January 5, 2016 Or a whole lot of different types of heat exchanger Quote Link to comment Share on other sites More sharing options...
johnny.race Posted January 6, 2016 Share Posted January 6, 2016 Thanks for the info I was going to go for 20mm copper Filling it with sand helps keep its shape when coiling I believe. Have you actually done any experiments with length, and any thoughts on what is best? Yeah I have. I got to a length of just over 3.5m of 20mm in a coil. And it did not want to work like it had when I had just under 2m of it coiled. A couple of things though ... my coiling ability was haphazard and shit. Some of it was alright but there were a couple or 3 kinks that i could not be fucked trying to work out. I had started trying to fix the first one when it occurred but it work hardened (by the looks of what happened) the copper and it fractured and cracked. I ended up cutting this piece out and carried on. It happened another couple or three times by the time i got to 3.5m. So there is this factor. Another thing was that (if you know anything about Waste Oil Heaters then you will know what I am on about. Me? I am a fucking expert on them) because i was in the experimental phase, I was not buttoning up the top each time due to the couldn't be fucked factor. i added some more copper to the coil so my draw was less than adequate due to all of the leaks i am guessing.But all this said ... check out the pics below. I am going to try this setup and probably do a decent job sealing it all up. Should work a beauty. 1.7m of 25mm copper pipe. Intend to 'shape' the heat flow so it absolutely murders the pipe but hopefully still keep its blowtorch like velocity up. We will see. 1 Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted January 18, 2016 Share Posted January 18, 2016 Johnny race please start a thread on waste oil burners you making because I want to build one for winter shed warming. Mof.. keep up the good work because again.. I want to build a spa pool so it's great learning from others!!! 1 Quote Link to comment Share on other sites More sharing options...
felixx Posted January 18, 2016 Share Posted January 18, 2016 Mof, that looks just like the 'BOOSTER' on my parent's old yunca wegj it used to boil the water in the cylinder it was awesome Quote Link to comment Share on other sites More sharing options...
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