I've only just started cooking in my RF and the one hog I cooked was in no need of humidity...and the ribs weren't too shabby either. I don't think it's necessary and I think that most folks here would agree based on some of the research I did when building mine.
In my experience the water pan puts monitor in the air but it doesn't go into the meat. It acts like an heat sync when full and doesn't help in the cooking process. If I was trying to reduce the amount of radiant heat coming from a baffle plate. I would rather use sand on the plate.
Jm2cw
Making memories.
Current Smokers: Backyard RF Offset and Hybrid RF Offset trailer rig with Cowboy cooker and fish fryer, always room for more........
I don't have any experience with a RF, but I agree with what Rodcrafter said.
I know my pit is hotter in the back, and I usually put a couple of loaf pans with water on that part of the grill. I do this both to block the radiant heat and to put some moisture into the air. But it's not critical to do on my pit, it doesn't make a huge advantage and I only worry about it on certain kinds of cooks when I'm particularly worried about uneven heat and potentially drying out the meat.
I don't believe that the moisture goes into the meat, but I believe a more humid environment slows moisture already in the meat from evaporating. I don't have any proof of that though, it just makes sense to me logically.
I also think a high humidity environment will probably cook a little faster too, as the moisture helps conduct the heat. Again, this is just my supposition, but it makes sense to me in the same way that a humid day feels hotter than a dry day.
I'd bet that the type of pit you're cooking on makes a huge difference in the usefulness of having a water pan too. If you have a lot of direct heat I'd bet a water pan is really important. With an offset cooker, less so, and with a reverse flow or anything with a good baffle system, probably even less so.
This has ben a subject that I've wondered about too. Someone should do a big government funded scientific study of different kinds of pits with and without a water pan. I love a good scientific study, and it would be great to see one that involved BBQ!
I agree CaliSmoke. The type of cooker really drives the use of a water pan.
I think a water pan helps with hot n fast cooks (ie...Myron Mixon). He cooks hot n fast and uses a water pan.
I know backwoods smokers preform way better if you use the water pan. I tried not to and it was a pain to control temps.
Altho I think a RF or OF prolly do not need water pans.
I believe the water pan dies what was already stated it keeps the moisture environment in check allowing the meat to stay moist. I do not believe a water pan puts moisture in the meat. I believe it keeps it from drying out.
Jm2w