I thought I'd share my 2 Kettles Technique that I've had great success with:
I technique I use that seems to work well is to use 2 kettles liquid extract, some dry extract and steeping grains. This is what I do.
put 2 gallons of filtered tap water in one kettle and heat to 155 F. Steep grains for 30-60 min. I usually use a pound of base grains (I like to use a Belgian Pilsner malt) along with any specialty malts. If I use the Pilsner I steep for an hour if not 30 minutes is enough.
While the grains are steeping, in the second kettle heat about 2.5 gallons of distilled water to 170 F. After the grains are finished steeping in the first kettle transfer the grain bag into the second kettle for 10 minutes to rinse all the sugars. This will give you a first running (kettle 1) and a second running (kettle 2) so to speak.
After 10 min. remove the grain bag from kettle 2 and bring both kettles to a boil.
When both kettles are boiling add most of the 2nd kettle to the first leaving about a half gallon of the distilled second runnings behind. You are going to use this to rehydrate your Liquid extract.
Now you have about 4 gallons of wert boiling. Add 1 or 2 lbs of Dried Malt Extract. I find you get the best results when you use a combination of Liquid and Dried Malt Extract. Usually about 1/4 is DME. For instance if I use 6 lbs of LME I'll use 2 lbs DME. This gives me a SG around 1.060 - 1.070.
You're also going to get better hop utilization this way with the lower gravity wert. Make hop additions as you normally would. Maybe scale back the bittering addition just a bit.
With about 30 minutes left in the boil begin heating the half gallon in kettle 2 at low/med and bring a suace pan half filled with tap water to a boil. When the suace pan comes to a boil place it in the sink and place the Liquid Extract Bag into the pan. This will heat the LME, thin it a bit and get it ready to rehydrate it in kettle 2.
When the second runnings in kettle 2 begin to boil. Turn of the heat and stir in The LME (that's been soaking in the sauce pan). Make sure you stir it good so that the LME and Second runnings are completely mixed together. The enzymes and sugars from the second runnings help rehydrate the LME and make it more fermentable. Once it's good and mixed, turn the heat on to low/med and sitr the LME constantly, making sure not to scortch it. Bring the temperature up so that's it's a nice liquidy consistency. This will help when you add it to wert with about 15 minutes to go in the boil. 1) it will be a thinner consistency and mix easier and 2) it will be a higher temp and help bring kettle 1 back to the boil faster.
With 15 minutes to go. Turn off the heat on both burners. Add the LME in Kettle 2 to the wert in Kettle 1. Stir in well. Turn heat to Kettle 1 on and bring back to a boil. This usually takes 5 or ten minutes depending on your burner. When it comes back to a boil finish the last 15 minutes of the boil.
This should give you about 4 gallons of wert. Chill down your Wert. Add 1 gallon and half of ice cold filtered tap water to bring up to 5.5 gallons. Pitch your yeast and enjoy your beer and peoples faces when you tell them it's an extract beer!
