I have a weirder problem, when I first got me real Glowforge after the PRU days, I had installed a 4” Louvered outlet onto my deck (people freak out that I am venting “laser exhaust” where people might be seated, but somehow the 3 fire pits are just fine?? Anyways the way our house is built the opening is only a few inches above the deck to get a clear space to the basement room where the laser lives. I noticed the first few times that I ran it the house would smell of exhaust, and since this was right after PRU days none of us had much experience. So I ran through the usual exchanging hoses, hose clamps and all the usual tricks for exhaust leaks. I then at someone’s suggestion put an anemometer onto the exhaust and it was putting out 95% of the expected flow (presumably some losses in the pipe, louvres and elbows). We finally traced the problem back to the inlet for the hood on our stove which sits about a foot away to the side. What we realized is the cold air is siphoned into the un-louvered hood hose and pulled into the house that way, as it only happened when it was cold outside. So the solution is to put the hood on 1, where it it barely audible and barely moving air, but just enough that the air movement is to the outdoors. Problem solved.
Oh and I’m the idiot who didn’t think about mounting the exhaust 3” above the deck in a place that routinely gets 6-12” of snow at a time (nor did the contractor either)… 
, so that’s on my snowstorm mental checklist to shovel a square foot around the exhausts (it actually does OK if the snow isn’t super wet, and since it is pumping the heat from our basement it does slowly melt a hole for itself.