I am new to the home brewing game and am looking to get a little info before I start buying equipment. How large of a brew kettle do I need if I am brewing 10 gallon batches?
For a ten gallon batch, you'll probably want to have about 11 gallons of wort at the end of the boil to account for kettle losses (dead space, break material, hops). If you figure you'll boil off roughly a gallon per hour and you might want to be able to do a 90 minute boil sometimes, your kettle will need to hold an additional 1.5 gallons. That puts you at up to 12.5 gallons of wort at the start of the boil. You'll need some extra space to prevent a boilover. Given these assumptions, a 15 gallon kettle is sufficient.
These are the numbers I used when selecting my new kettle. They worked well for me. Your mileage may vary.