Reworking an immersion chiller

I have a good size 50 foot 1/2" chiller that I have been using for years. I now have a 15 gallon kettle and the dia of the chiller in comparison to the kettle leaves quite a bit of the chiller out of the kettle when trying to chill. The copper is pretty stiff.

I haven't messed with it too much but was thinking of trying to straighten it out and coil it around a new larger dia so I can help it work better. With the chiller being probably 10 years old (got it from a friend who brewed 5 years with it before giving it to me 5 years ago), it seems the copper is a little stiffer than I thought it should be so I'm worried I may end up ruining it.

Any plumbers out there can chime in? Is this more than likely going to crack on me or is there some trick that I can use to get this copper re-formed and working a little more efficiently. Thanks

Not a true "plumber" per se.............I doubt it will crack, but it will be "work hardened" from forming to it's present shape, and the heating and cooling cycles.

From your post, you are wishing to increase the diameter of it, yes?

If so, you can probably get away with "opening it up" to better suit your keg diameter, if done by hand.

Me personally, I would not attempt to straighten it out unless you have some type of fixture or rollers you could pass it through to help straighten it.

Do a little reading here about "annealing" it to restore some workability.

http://www.practicalmachinist.com/vb/general/what-temperature-anneal-copper-246989/

Anneal it, take a blow torch and gently from a distance then come closer warm the pipe, watch it turn colour, let it go to purple moving the flame all the time, then take the torch away and let it cool, then do it again and let it cool in the air. You will be able to feel the pipe move in your hands, just gently reshape it. When it feels like it's resisting anneal it again.
I suggest your try this out on a piece of scrap first to get the hang of moving the flame around and what it feels like when it moves and when it's resisting. When your ready for the coil anneal little bits at a time then progress around the coil, wearing gloves of course. Some guys may tell you to quench after heating, it will work without quenching. Quenching a coil like this at the right time will be practically impossible unless you have access to a oven furnace.

Sounds easy enough. I have a MAPP torch I'll see if that has enough heat to make this work.

How much do you value your time? Personally I'd sell that IC to a fellow homebrewer for $50 and just start over with a fresh coil of 1/2" x 50'. No brainer.