First time getting heavy white smoke.

[HARRYSTOWN]

I smoke on a UDS. Did my first brisket Sunday. Had a mix of Blue K and Hasty Bake Lump burning hot about 325. Added 4 fist size hunks of Apple wood purchased from a overpriced BBQ specialty retail store. Smoke rolled out thick and white. Let it burn for a hour thinking if the wood got hot enough I would see the blue. After a hour no change. Popped the lid off and put on a heavy leather glove and hand fished the 4 burning wood chunks out. White smoked stopped immidiately and the thin blue was working the UDS. Just wanted to share experience. The wood did look a little knarley and old. Kinda reminded me of old pieces of drift wood. I dont know if they sold me crap wood or maybe chunks were too big. I had used only small chunks of hickory and cherry before and never had problem. The wood was actually on fire when I pulled it out, so I would have thought I was getting good combustion. My clothes smelled so smoky from messing with the UDS that I had to shower and change again. Smelled like I was in a house fire...

[Lake Dogs]

If the wood was dry, then the odds are high that you had too much wood on the
coals and choking the fire (thereby producing heavy white smoke). Add one chunk
at a time. That will most likely fix the problem.

[Bamabuzzard]

As Lake Dogs mentioned may have had too much wood on at one time.

[BobBrisket]

White smoke is normal with the drum. Sounds like you had the right amount of chunks. The white smoke with the drum is caused by the fat dripping onto the coals. If the smoke smells like Q(in other words, smells like greasy fat burning off on the coals) then you are okay. If it's black or has an acrid/strong smell then it's a coal issue. I freaked out the first few times I used the drum as well, cause of all the smoke it makes. But after a while, it should settle down to a nice plume of white smoke.

[HARRYSTOWN]

I had to be the wood because I hadnt put the meat on yet. White smoked stopped soon as I pulled the wood out.

[BobBrisket]

My bad. I assumed the meat had been on a while already. How do you set up your coal basket? How do you start it up? Minion/Weedburner? Embed the chunks in the coal so they go off at different times in the smoke. Some in the center and other at the far end of the basket. If the chunks were about fist size, then they should have been okay. That's about what I use. If they were on fire with the lid closed then it also sounds like it got too hot too fast since you were at 325 and since you had a mix of lump, that could be the reason why you had a hot smokey fire really quick.
A weed burner is great for the UDS. I hit the center coals with the burner for a minute or less until just the ends of each briquette are ash colored. I leave it alone for 15 minutes or less until the coals start catching then on goes the lid and intakes get opened up. I then start monitoring the therm and start closing vents as it reaches the target temp. It's much easier to catch the temp on the way up, then to try and bring it back down.