Welders use a variety of methods in their trade. Different types of welding are better suited for different purposes and contexts. For example, stick welding is a versatile form suitable for most metals and alloys. The most common types of welding include:

• Stick welding: $100–$1,000

• Metal Inert Gas (MIG) welding: $250 and up

• Tungsten Inert Gas (TIG) welding: $250 and up

• Gas welding: $150 and up

• Forge welding: $15–$25 per hour

Cutting rectangular ductwork requires careful measurements and the right technique. Use a measuring tape and pencil to mark the cutting lines accurately. Tin snips are excellent for straight cuts on smaller ducts. For more extensive or thicker rectangular ducts, a reciprocating saw with a metal-cutting blade is effective. 

Ensure the duct is well-supported and secure while cutting to prevent wobbling and maintain precision. After cutting, use a metal file to smooth any sharp edges, ensuring safety during installation. 

You should not do your own welding unless you have the proper training and experience. Most home electrical systems can only handle MIG welding, which creates weaker bonds than TIG welding and won’t work on certain metals or metal thicknesses. Both welding forms usually require the use of shielding gas, which can be dangerous to store at home. Additionally, welding machines create temperatures of over 3,000 degrees, and the sparks can blind you if you don’t have the proper equipment. As such, it’s usually better to hire a professional welder for your welding projects.

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.