I've done this - for cement work. No heat needed.

What you need is a bending jig. The one we made was built out of a zillion scrap 2x4's, forming a fanned out arc in the shape we wanted to get it was like laying bricks - we used 18" lengths of 2x4 air-nailed to longer sections of 2x4's that ends of the wood were spaced at about 4" intervals.

Put your hand flat on your desk, splay out your fingers - see how there's sort of an arc formed by your finger? Bend a piece of wire over your fingers - that's the basic idea. Our arc had a section of iron pipe at one end - we stuck the rebar in there and then we simply pulled the rebar over the form - it was hard - until we got the curve we wanted. this was for a project to build a curved concrete wall for a landscaping project.

There are also tools that can be rented to do this, but they are expensive. You set the radius you want and it's got these rollers that pinch the bar and roll it through. You can do small bends and large curves.

For a cheaper and easier solution you might want to consider Conduit.