Okay, got it. The 3500 Watt unit will bring 8 gallons of water to a boil here in Denver (6,000', or 201 degrees F) in just over an hour. It's a nice, rolling boil. I'm looking forward to doing a 5 gallon batch on the new "system." Here are all the relevant time-temp curves - the 5-gallon curves are on the 1800 Watt unit, the 10-gallon on the 3500 Watt unit, 4 gallons and 8 gallons.