Make a 22mm copper pipe into a coil??

[Spectric]

Go down a scrapyard and look at the old copper hotwater cylinders and they have a copper coil inside that may be what you want. Failing that why not use the plastic plumbing pipe which comes in coils anyway, and will take water at 70 degree's C.

Failing all this then why not use a cast iron hot tub and have an open fire underneath, just be careful or you could cook.

 

[Ozi]

Just a thought, it doesn't have to be a round coil. What ever diameter of pipe you chose buy a standard pipe bender and make a square or hexagonal coil - you may curse me later.

 

[Dave Moore]

Hi,
I’ve sand loaded and bent standard lengths of copper pipe years ago at work but I wouldn’t recommend trying this way to make a coil. I think it would be better as suggested to use a soft copper coil being careful when opening it out to the diameter you want as copper work hardens. We use silver solder for our work as it takes a higher pressure and we are working on Oxygen lines.
Regards,
Dave

 

[Myfordman]

Has the effect of hot tub chemicals on copper pipe been considered before effort is put into bending?

 

[jonn]

My son is making a hot tub. He needs to make a 3 metre x22mm copper pipe into a coil for heating the water. I needs to be about 350mm diameter.

Anyone know how to make it without collapsing the copper pipe??

1. Anneal the pipe - properly.
2. Make a jig like shown in the picture of some hardwood. See to that the flanges are close to the diameter of the pipe.
3. Put the cooled annealed pipe in the tool, and start bending. The flanges will prevent the pipe collapsing.
4. Take your time, don't force the bending.
And yes, it works very well. Used similar ones to bend brass piping for fuel lines on RC model airplanes.
PS: Don''t put sand in the pipe as that will have the opposite of the desired effect ☹