Heat exchanger tubing

[Bad Wolf]

I'm sure this has been addressed but I'm having trouble sorting through all the threads.
I want to build a copper coil type HX similar to what STSS offers. The TARM guy recommended two 120' coils. From my reading this is 3/4 type L tubing, 22" dia and 43" high. Where is the cheapest place to get this tubing? Does it connect directly to regular 3/4" copper pipe? From the pic I can see it looks like it does i.e. sweat fittings not compression fittings.
It looks like I would want to form it on a mandrel, then tack solder the vertical pieces for rigidity. Does anyone have an idea how much springback to allow for if any?

More questions to follow.

Thanks

Greg H

 

[Nofossil]

I'm sure this has been addressed but I'm having trouble sorting through all the threads.
I want to build a copper coil type HX similar to what STSS offers. The TARM guy recommended two 120' coils. From my reading this is 3/4 type L tubing, 22" dia and 43" high. Where is the cheapest place to get this tubing? Does it connect directly to regular 3/4" copper pipe? From the pic I can see it looks like it does i.e. sweat fittings not compression fittings.
It looks like I would want to form it on a mandrel, then tack solder the vertical pieces for rigidity. Does anyone have an idea how much springback to allow for if any?

More questions to follow.

Thanks

Greg H

I used standard 3/4" soft copper and coiled it around a mandrel that I made out of plywood disks and 2x2s. I used 1/2 hard copper for vertical supports. lashed on with copper wire and then soldered. No springback - I used a larger mandrel than the original diameter of the col it came on. Mechanical precision is not necessary in any event.