I've watched a few videos of brew day on YouTube and I understand some of it but I just don't understand a few things, like if I do BIAB, do I need to sparge or fly sparge, do I need to convert an ice chest to a lauter tun, do I still need to mash if I do BIAB? I've read how to brew, the AG section like 4 times and I don't know if all the technicalities psych me out or if my mind isnt concentrating on what I'm reading...
I moved to brewing BIAB a few months ago, and I don't think I'll need to move to a three-tier setup for quite some time, if ever (I just don't have the room). Here's my equipment and process:
7GA turkey fryer I bought at Walmart - many will say it's too small for doing any big beers, but I've managed 15lbs of grain in it once or twice, so I don't think it's limiting me too much; if I need extra gravity, I'll sub out some of my base malts for DME to get where I need to be. However, get a larger kettle if you feel so inclined and don't want the constant risk of boilovers.
3-4GA stockpot - I heat my sparge water on the stove in this. Works great for me, and the volume is just about perfect for my sparges.
Fermentation bucket - I batch sparge in this (dunk the bag in), and once the boil gets going, I clean/sanitize for wort later.
Process:
Since you don't have to worry about stuck sparges and all the efficiency hassle that full fledged AG brewers have to worry about, double crush your grain! Get as much of that starchy goodness exposed to the water as possible. I'm usually getting around 75-80% efficiency with my process, so I'm pretty happy.
Heat strike water (what you're going to put your grains in for the mash) to the desired temp in your kettle with your mesh bag. My water usually drops about 10 degrees (f) after adding the grain, so I'll heat mine to about 160 or just above to achieve 150-155 for a mash temp. For the amount of water, you will mash at the same ratio as other AG brewers, 1.25-1.33qt/lb of grain. So, for example, say you've got 10lb of grain, you need around 13qts of water, just over three gallons. Once the strike water is to your desired temp, dump the grain in and stir like crazy until everything is mixed well. Cover, remove from the burner, and wrap it in a blanket or two to maintain temp.
Once your mash is complete, stir it up again to free up as much of the converted sugars as possible from the grain. Then, pull the bag up to drain it out. Don't worry about the nay-sayers who'll tell you to never squeeze, squeeze the piss out of that bag. It's got sugars in it that you want!
Then, I take my preheated sparge water (from the stockpot on the stove), and dump it in my fermentation bucket. Put the grain bag in, stir up the grains more to expose them to the water, and let it sit for a few minutes. Then, repeat the drain and squeeze process, and you've successfully sparged!
Dump it all in your boil kettle, and you're off like you were when you were extract brewing (boil, hops, chill, sanitize, yeast ... beer).
That's it. I love the simplicity, so that's why I do it. I know others can think otherwise, but the process works wonderfully for my setup and location, and I make great beer.
Hope that helps...