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View Full Version : Amazing self-dirtying, dirt-sucking house


fixitnewbie
June 30th, 2008, 06:59 PM
My house is driving me crazy: the central HVAC blows out dirt, and lots of it. It's really bad near the outlets where the heated or cooled air blows into the room, so it's definitely the HVAC system that's the culprit. I've gotten several explanations for this over the years from various HVAC companies, and have gone as far as having the entire system replaced - more than once! Yet it continues to get worse.

I have an "air cleaner" (or whatever it's called) that's supposed to take all the extra crud out before it even reaches the regular AC - the kind that needs an annual filter change. Mine needs a new filter every couple of months. The last time we replaced the system, the salesman swore that I wouldn't need a filter on the intake vent because of the air cleaner, but when the dirt problem was obviously worsened after installation of the latest system and new ducting, I was told that yes, the intake vent DOES require a filter. It didn't help.

Right now I have it licked: I'm using window ACs, which are easier on the electric bill, anyway. But I'd really like to get the central unit working properly - and running clean.

The ducts themselves are supposedly sealed, though the "testing" for this was completed by the company that sold me the new, supposedly sealed ductwork. They also tried to explain the increased dirt around the vents as being caused by "static electricity." Sure, and if I blow on a pile of sand, it will end up sticking to my face, right?

The house is an old one and I'm certain needs many patches and plugs throughout. But why would a supposedly sealed HVAC system, including a special air cleaner, be blowing out dirt with the cooled or heated air, regardless of how many holes may be in my house?

I can't afford to replace the whole thing again. I can't afford to do much of anything right now. I'm hoping that someone can walk me through some diagnostic steps (what do I check first, etc.) so that maybe I can isolate the real problem - and maybe even FIX it. I have a son with asthma whose health has suffered because of this, and I have replaced far too many computers and peripherals because their life expectancies are shortened in this environment.

The dust is SO bad that when I recently moved my refrigerator from the spot it had been in for about 3 years, it looked like there was a 5-inch thick later of gray felt behind it - halfway up the height of the fridge. I looked underneath, and there was the same "felt" completely encasing everything I could see. Thank goodness I caught it before the fridge died, too.

Sorry for such a long query, and thanks in advance to anyone who can help me figure this one out!

bobl
September 9th, 2008, 08:29 PM
This is a really interesting problem.

I remember seeing a great photo essay of how a new house blew inches of dust around all the registers. The owner was going crazy trying to get builder to fix it.

The problem turned out to be a section of duct work with a large leak. It was pressurizing the interior cavities of the house and attic and forcing the blown insulation, dirt and other stuff through any cracks in the wall and around registers.

I'm starting to think about replacing our 20 yr old HVAC system (Trane unit still seems ok, though) and while hunting around for info I found a web site with this problem and great pictures, but now I can't find it again.

I am also aware of mostly anecdotal accounts of duct cleaning services tearing up the flex-duct in attics, creating similar dust issues in the house - big streaks of dirt around registers is the main clue. Another worse case is leak in sealed crawl space forcing dust into house through cracks and crevices.

I have read are ways to test for leaking ducts but I don't have any experience with them - they seem like they must be done carefully or you will get misleading results.

Also services calim to be able to inject some sort of sealant but that seems really far fetched.

Still, you might try this duct leakage approach because your symptoms sound very much like many accounts that I read a while back.

This is link dated but still interesting.

http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/98/980109.html

This doesn't sound like your problem but it explains positive and negative pressure in the house better than I can.