this information was provided by SOGGYSHOOTER! thanks!
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Although I too prefer charcoal over gas, I do use gas when I want things either sped up or I need better heat control without babysitting the smoker. My gas job is a Brinkman water smoker. The best way I have found to add smoke flavor is to soak chips, not sawdust in water until damp. Then you can put them directly on the coals or in a foil pan. Either way will work but directly on the lava rock works best for me.
What happens this way is you get a lot of smoke quickly and then its done and allyou have to do is finish cooking.
If your plan is to actually smoke for a long period of time rather than cooking dinner, go with a foilpan. When I do that on my Brinkman I put the chips (or sawdust) in this case in the water pan but put it directly on the lava rock rather than the place it normaly goes.
I had problems at first with mine since it would get to hot 235 deg. on its lowest setting. I ended up buying a second burner and screwed tiny sheet metal screws into some of the holes to cut down on the flame. A modification that I am sure Brinkman would not approve of! It works great. That burner will now regulate from 140 deg to 250 deg. Now it smokes like it is supposed to.
The one thing this setup we have really does good is chicken and ribs. The water pan keeps things moist so I really don't have to pop the top to check things out. I do have to open it up to switch the grills around since it is set up like a verticle tube with one grill above the other.
We have a dry rub we use for both pork and chicken that sits overnight and it is great. Very simple. You can ballance out the flavors but it is salt sugar paprika garlic powder onion powder cayenne pepper and black pepper. Just dont go over board with the paprika as it will give you a bitter flavor.
In the water pan we add to the water a little bit of apple juice or vinegar. Not much vinegar but it does something subtle to the flavor. more apple juice is better.
I hope this give you enough pointers to start out with. You will have to experiement a bit to get things right but well worth the effort.