Professional Member
Originally Posted by leeannwc
I have just about every piece of equipment you would need, including an infrared camera. If you are willing to send me an email (from my profile) we might be able to work something out.
Professional Member*
Have you checked to see if there is a Comfort Institute member contractor in your area?
www.comfortinstitute.org
Try the "Find a CI contractor" link.
All comfort institute members have the equipment to do the testing you need.
Regular Guest
I would almost bet my life that the dust is cellulose. after just a few hours you can run you finger across a surface and come away with enough dust to roll into a ball. then you can crumble it into a paper-like consistency. at least two HVAC professionals have seen it too (one under a microscope) and agree.
today i turned off all the HVAC at about 8:30 am, waited a few hours to let things settle, then began cleaning around noon. i finished up about 4:30 and left the house. I just returned at 8 pm and the surfaces are covered again! is this enough time to validate that it is not coming from the ductwork or could the dust still be suspended in the air and just dropping? interestingly the house maintained its temperature....even now it is still 70 degrees in here which would make me think that infiltrations are negligible....is that correct thinking? nothing makes sense anymore. a good tornado to take it all away would be a blessing.
Professional Member*
Did you try closing all the doors during that test?
Professional Member*
Another thread just made me think, what is the humidity in your house?
Regular Guest
Wish you the best of luck, I know this must be driving you crazy. I will be following also so please keep us updated.
Regular Guest
i did not close doors. we have a very open floor plan, so the only thing i could isolate really would be 3 bedrooms upstairs.
we are maintaining a RH of about 43%. last winter we could not get it to reach 40, but we discovered some significant infiltrations and sealed those. now it stays steady pretty close to what i have it set at (44 or 45 i think).
i still have the air handlers off, but it will probably be in the 30's tonight. i'm thinking of moving us all to the basement for the night, cleaning some surfaces again and seeing what i have in the morning. i thought perhaps there was still a lot of dust suspended and that i should give it some more time to rule out the ducts as a source. i have left the units off for a few days at a time before, but i can't remember for sure if i tried both upstairs and downstairs and maybe i cleaned before the air had a chance to settle. thought i'd try it again today. if i seem like i'm rambling, its because i'm going mad! any advice? should i turn the heat back on or move the family to the basement for the night?
Professional Member*
Closing them may not help but would still try it. Can you post some pictures?
Regular Guest
what would you like to see pictures of?
Professional Member*
Mechanical systems, attic, interior, exterior. Someone may see something that was overlooked. I can look at a house going down the road and come up with some pretty accurate guesses about problem areas in the building envelope. It's real easy if we just got an inch of snow. A picture is worth a thousand words.
Last edited by stvc; 11-29-2007 at 12:04 AM. Reason: sp
Regular Guest
you had said your ductwork was cleaned and inspected.i was just remembering something i came across a while ago.went back to a job the next day and found that the jamoke doing the popcorn cieling thought it was a blast to shoot his cieling gunk into our ductwork probably not relivant to your problem but though i would throw oit out there
Regular Guest
no popcorn here
i will try to post some pics. in the meantime, the house plan is the "Montaigne" at frankbetz.com.
notice the gable vents. tomorrow i am going to try covering them with plastic. we are on a hill and and have a tall home. we get lots of wind hitting the front of the home and it rips through those gable wents. the one on the right of the elevation is over our master closet and yesterday when i opened the attic access in that closet it was like a hurricane up there. the other attic also stays quite breezy. My thoughts are that perhaps there is too much ventilation up there and that is creating a positive pressure in the attic. we also have soffit vents but they may not be able to handle such an influx. that's my target for tomorrow. i don't know where in the world the air could be entering on the finished side as much sealing as I've done, but it's worth a try. of note the master suite is batted fiberglass but the main attic has about a ten foot drop to it and i can see blown insulation has fallen over.
i left the heat off for the night so i'll check dust levels again in the am, too.
Professional Member
It does sound like you have a significant pressure buildup in the attic. If the pressure difference between the attic and the interior is high, dust will find every little hole that you can't find and get to the inside. Being able to take the attic to a negative pressure with some sort of fan would either diagnose or eliminate this as a contributing cause, with the holes in the envelope the root cause of the problem.
If you have soffit vents, and you cover the gable vents, the pressure may not change or could go up unless you have a ridge vent or turbines for exhaust.
Regular Guest
I think this is a very valid point and should not be overlooked. As previously pointed out, "over" filtration will cause reduced airflow, which in turn will cause reduced performance of ANY filtering method. Inducing outside air will not only provide 'new' air to the space but will also provide make up for any exhaust that you may have.
Oh, and even a closed chimney will vent, especially in windy conditions (stack effect).
Regular Guest
Yes, I thought that all through. My husband actually offered to go up in the attic this weekend and cover the gable vents, but I told him that would only be treating the symptoms and not the root problem. I cannot for the life of me see where we could have bypasses from the attic to finished space...I sit and just look around every day for something else to seal up. I'm to the point now, though, that I just want a break from the symptoms. We need some respite. It would also help rule-out ducts wouldn't it? I still have the heat off but I can't really tell any difference. It is hard to determine if the dust settling might have already been in the air and we have accumulated so much that one good cleaning is not enough to get it all...I'm sure it will still be around a while once we do resolve the cause.
I thought of the venting too and we do not have ridge vents or turbines?? I'm not sure what the contractor was thinking because he only had soffit vents planned...I had him add the gable vents for cosmetics having no idea at that time how it could impact anything else. It seems to me that there is really nowhere for the air to get out.
Professional Member
Without turbine or ridge vents I would guess the gable vents do not have enough area to relieve the pressure from the soffit vents. So if that is the case, then at least you know the pressure difference exists to be the driving force for the dust. But if there are no holes in the envelope or the ducts, it won't really matter. So there still has to be a path, which is the root cause of the problem. Your blower door test should have identified a composite hole size in the envelope. Do you know what that was? And if I remember correctly, there have been numerous corrections made since that test so was there much difference in the dust after the corrections?
Professional Member*
You may be onto something regarding the air movement in the attic. Soffit and gable end vents are mainly for natural convection ventilation, with cooler air entering the soffit vents and exiting the gable end vents. Wind can change this pattern, and if a gable end vent is facing the prevailing wind, it can introduce a considerable amount of air into the attic, pressurizing it to the point where the soffit vents do not have sufficient free area to relieve the pressure. Air goes wherever it can find a path, just like water.
You may have done an extraordinary amount of sealing between your living space and attic, but if you have wiring in the attic that goes down into the structure through the top plates of the walls, and those top plate penetrations are not sealed, that's yet another point of entry for air and dust.
However, it would now seem your focus should be changing the air dynamics of your attic. You might wish to go ahead and have your husband tape up some plastic over the gable end vents temporarily, just to see if that makes a difference regarding dust accumulation levels in your home. IIRC, only 10% of all airborne dust will settle out or is large enough for the average home a/c filter to catch. Since you have not been running your system and are still accumulating dust at a good clip, it strikes me you have more dust coming in, replacing what is settling out of the air. If I were at your house, knowing now what you've said about the attic conditions, I'd be looking hard at that aspect and seeking change.
Regular Guest
I know some great professional minds have been working on this problem for awhile now but please fill me in... has a blower door test been done to identify the overall amount of house leakage? Would our pros agree or disagree on the value of this?
Best of luck -- Pstu
Regular Guest
Wow.....
It appears you have done your homework and tried to do what the Pros have suggested. Time to quit until you find the source.
Now, why don't you get a couple boxes of a good quality filter. Change all the filters in your returns ( don't know how many you have). Set the system to fan on all the time. (This will keep the dust suspended)
Change the filters every 2 days until you see a significant decrease in dust. (checking the filters for dust accumulation)
I would think this will help until the source is found.....
Good Luck!
Professional Member*
There is no reasonable way to provide adequate whole house filtration to the degree leannwc needs to mitigate her dust problem. Most of the dust will settle out before it reaches the filter...her post history supports this...she is continually cleaning up dust from surfaces all over the house. To provide the amount of filtration and air circulation to keep these particles in suspension until they reached the filter would make the house unlivable.
The cause of the dust intrusion must be found, and from my vantage point I think she's closing in on it. I think she should go ahead and temporarily block the gable end vents to see if that makes a difference in dust accumulation levels. She will always have dust. But her complaint has consistently been the rate of dust gain is intolerable...I don't think she's asking for her home to be impeccably dust free, just reasonably clean.
One other thing to look at is the attic access itself. The pressurized attic can force a lot of dust into the home from this access area if it is leaky, and if the attic is breezy, you can be sure it is stirring up dust in the attic.
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