I've read about problems with blowing smoke into duct systems to find leaks. One article said that the smoke product left some bad residue inside the system.


Does anyone have a good product/system/technique to recommend to find elusive duct leaks while "doing no harm?"


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I would call or email the Energy Conservatory. They have some very knowledgeable folks there would will know what's current on this. Let us know what you find out.

I bought a theatrical fogging machine.  I was really jazzed about using the fogger from everything I read about it was pretty cool, non toxic, fog evaporates relatively quickly, no odor and leaves little residue by the machine.  Well opening the order I discovered the machine did not include the fogging solution!  Big bummer, I had to order the fogging solution.  I will let you know how it works  and if I wasted my money or not.  If any one of these machines  can you let me know any experiences, good or bad!



I have not found it to be very helpful and have tried on a number of occasions with a  theatrical fog machine.  If it is a big leak or at the air handler, then you can see some smoke.  If the leaks are at fittings and connections, by the time the air moves through the insulation layer, it is scrubbed of smoke.  Limited lighting in attics and crawlspaces just adds to the difficulty.  If you were working in with uninsulated metal ducts, I can see where it might be helpful.  For the ductboard and flex ducts I typically see it has been more wasted effort than helpful.


I have found the hand held Wizard Stick smoke wand to much more helpful.

   Theatrical fog is the same stuff you put in kids' electric trains to make the steam engine "steam."  It's also the same "juice" we put in our Wizard Sticks (another kids' toy, and a much better choice than the titanium tetrachloride in smoke sticks if testing is being done in an occupied house).

    Two lessons about theatrical fog:  (1) put plastic bags over any activated smoke detectors  and (2) buying the fog juice online gets expensive because of the shipping.  Check local music stores.  If they sell electric guitars and amplifiers the odds are good that the sell fog juice.

I will use the fog on occasions to either impress homeowners and contractors on leaky systems. It has helped find the really big airholes. I have to admit I was stumped last time, I used the fogger on a duct system that I could not get any pressure on. I had guys in crawlspace and house, very little fog made it to registers. Did some more investigating... when the original hvac was installed, the contractor built a closet for the return where the old gas furnace had been, using existing walls, etc. HE INCLUDED THE PREEXISTING CHIMNEY, UNSEALED, into the return cabinet!  The fog was going up and out the abandoned chimney! ARRRRGH. Gotta go and find some more airholes!


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