Since water heaters are primarily made of metal, they’re commonly accepted by scrap yards and collectors. Don’t expect to fetch a high price, though—water heaters are mostly steel and aluminum, which aren’t high-value metals. Some components are made of more valuable metals, like brass and copper, but they’re a small portion of the heater and won’t affect the price much.

Cutting round ductwork requires precision and the right tools. A duct cutter, specifically designed for circular ducts, is ideal. First, mark the cutting line on the duct using a measuring tape and pencil. Then, position the duct cutter's blade on the marked line. Apply steady pressure, rotating the cutter around the duct. The sharp blade creates a clean, precise cut. Alternatively, a reciprocating saw with a metal-cutting blade can be used for larger round ducts. Ensure the duct is securely held in place while making the cut to prevent slips and maintain accuracy.

This all depends on the tools you have on hand and whether you’re trying to cut a straight line or shapes. 

The best tool to use for straight lines is either a circular saw or table saw. When cutting shapes, a jigsaw will be the easiest and most precise tool to use. 

Your typical household tools will not cut a metal pipe. To cut a metal pipe, you’d need more specialized tools like a pipe cutter or circular saw. Do not attempt to use these tools without taking proper safety precautions and wearing safety gear. It’s usually safer to let a pro cut a metal pipe, especially if you’re not confident in your skills with a heavy-duty saw.