Just looking for some advice. I purchased a 15 gallon kettle to brew 10 gallon batches. The one I purchased is about 20" diameter. So lots of surface area. I brewed my first batch last week with it. Ended up boiling off almost 3 gallons in 60 min boil! I know that the flame can be reduced so the wort is just at a low boil. But was wondering if I could do anything else to reduce the boil off amount?