pointers on 'in stack' copper tubing coil

[dudevato]

I have a wood stove in the shop that I can experiment with, to get thing figured out, before I tear into my 'in house' stove.  What I'm intersested in: Is there a certain type of copper that is easier to work with (bending it into the coil, that I figure will be some 6 to 8" dia, then some 2 feet tall) I'm conserned about the tubing 'kinking'. I'm thinking this will thermosyphion into a 30 gallon tank that will be just the other side of the wall the stove is up against (some 4-5 feet 'coil to storage tank')  I'd like to get any input you care to offer, as far as dia. of tubing/size of storage tank/etc.  I use the stove for an hour or 2 in the morning and for 3 or 4 in the evenings.  It is a homemade stove, I can cut down the oxy intake some, but it is by no means a 'smokin' stack/ air tight type.  Thanks for your time and knowledge.

[stop4stuff]

i'm not sure what dia tube you need, however if it is microbore you end up using, a method of coiling a tube is to pack it with sand or salt beforehand... the method is described here; http://www.bio-power.co.uk/exchanger.htm

[picmacmillan]

dudaveto, i have seen someone who made a square tank out of stainless steel and then bolted it to the woodstove,it had a funnel shaped mouth at the top which always had a little steam coming out to put some moisture into the air, it also had copper pipe coiled around the stovepipe....just thought it might help in your endeavors.......don't know where your from but you can get pipe bending tools pretty cheap on occasion and they fill them up(the pipe) with sand so they don't kink when being bent...have a good one...pickster

[walsdos]

Dudaveto I have used bending springs successfully. attach 1 to the appropriate length of cordthreaded through the straight pipe & pull it through to the point being bent. I have also made a double walled stainless (304) chimney whichheated low pressure water quite well,Dimensions... 8" i.d. 10" o.d. 48" long

[JW]

Hi Dudevato,

 I have done this many times. There are two grades of copper tubing, hard and soft anealed. Use the anealed if possible, Mcmaster Carr .com has a nice selection. Also if you get heavy wall tubing it will have less a tendecy to kink on you, generally this stuff works the best, wheither its hard or soft grade.

 Get your hands on a cardboard packing tube thats the desired diameter you what the coil to be and simply wrap the tubing around it, while holding the start of the winding to the packing tube. It should work fine. I also do this with 316L stainless steel tubing(and no torch). In that case what I do is, find a nice round piece of wood of the proper diameter for the finished coil, hold it in a lathe or some sort of rotating fixture. Then make a small strap with 2 holes in it, and lagbolt the start of the winding, then turn slowly(by hand!!!) and you'll see it works real nice, with copper you generally dont need such a heavy duty fixture, but it wouldnt hurt to replace the cardboard shipping tube with wood, and lag the start of the winding, just dont crush the tube when you tightn the lagbolt holding the braket. Then start to bend it around the form or tube. When I bend heavy wall 3/8 copper tube, i just use the cardboard packing tube on a table(vertically not horizontally) if the coil dosnt have to be very long.

JW  

[weldingrodd]

Hi Dudevato

Just make sure you use "soft copper tubing" and be sure its not refrigeration tubing.Larger dia of tube more capacity you get.

Spoke to a buddy who heated his water with a seperate stove just for water into his electric tank and he coiled the tube inside the stove pipe  but was sure outside would have worked very well.(he used a small circulator pump)

You wont need to fill the tube with anything, as soft tube bends and conforms easily.I would use compression fittings to make connections and you have to be careful what type you buy some are same as pipe dia some are restricted so get the ones with the biggest hole.

I posted under Remote Living Water back around 11/14 or 11/18.(heating water with woodstove) Am just about ready to hook my extra preheat tank up and am confident that with increased call for heat as temp outside drop I will have no problem egtting a good start on my heated water and may not neeed any electric at all. Will let you all know how it worked out.

Also if you can find a piece of 6 inch outside dia pipe, say a junkyard maybe You can easily roll the tube around the pipe and make as tight a coil as you like.There was post somewhere on here this week that had a diagram of a heat exchanger used to add to warm air furnace system...may have some hints on what you need to make your coils with.

I have used gallon paint cans to make coils before... Rodd

[rotornuts]

I like the idea and have considered it as well. The flexible copper avaialable at most hardware stores should work fine. I would start with a 50' roll of 3/8" and coil it to slip over the outside of your pipe then slide the next size stove pipe over top to make it double wall. Stove pipe comes in 1" increments so with 3/8 wraped snugly it should fit. I would not put the coil inside the pipe due to creasote build up and the inability to clean the inside of your pipe. Seal the ends of the outer pipe and it should work almost as well. Also if you have a flue damper the coil will have to go ahead of the damper to collect the most heat. as for coiling the pipe the above suggestions are good one's, no need to fill the copper with anything though. Arigid pipe form such as pvc has worked well for me.

Have fun and lets us know how it's working.

[troy]

Don't forget that if this is a closed system, you want to graft on a temp/pres safety valve (like on water heaters)so you don't get a steam explosion or burn.  The other alternative is a system that is not closed so it can vent pressure to the atmosphere all the time.

Good luck, have fun, play safe!

troy