My current kettle will hold 3.5 - 4 gallons (safely), so I fill it, steep my grains, and then add some of the extract. In the mean time, I also put another 1.5 gallons in a second pot, and keep it just off a boil. As the main kettle volume drops from steam loss, I top it off with the hot water, and then refill the hot water pot to keep it full. During the last fifteen minutes, I divide the remaining extract between the two kettles, topping them both back up, so that I have a complete five gallons. I whirlpool the main main kettle, and begin running it through my CF chiller. When it is about halfway down, I top it off from the second kettle, whirlpool again, and then start the flow to the CF back. So far this method has worked very well for me.