" I change the a/c and heat filter every month with the cheapest filter since I was told they don't block as much airflow and trap more dust."

The cheapest filter is either going to allow more airflow and also allow more dust thru, or contrict the airflow and clean more dust.

Ony the expensive ones will do both effectively.

You may need a professional to come in and clean your ducts. We change our filters every three weeks. The house is only 2 years old (barely), but it sits in the country in an agricultural area, so there is lots of dirt in the air. I also have indoor pets, but even when the are kenneled, we have amazing dust issues.

When you were gone for two weeks, there was (very little) air moving about, no doors being opened (pulling in that "fine dust" that gets on your car), no one stirring up that dust, and the CHEAP air filters that are allowing airborne particles to pass right thuru it. No one opening and closing blinds/shades, no clothes being folded, beds being slept in and made. IOW, dust is on EVERYthing and it's EVERYwhere and it doesn't just come from outside dirt. You live in an dry and dusty area. It's gonna happen. Do you have carpet in your house. That's another culprit. Not only does it "hold it", it creates it. In addition, your AC vents probably need cleaned. Your single paned windows are likely to be leaky. Have someone (on the inside) hold a candle at the edges of your windows. Using a hairdryer, someone on the outside run the dryer around the edges of the window and see if it affects the flame of the candle. If so, you need to caulk (or new windows). We built our little starter home in 81 and had double paned windows. This summer we just upgraded to double hung Low e2 vinyl windows.
Monica

The cheapest air filters do NOT do your furnace or A/C system any favors! They do NOT trap more dust. Like fotostat says, you would be better off with a more expensive filter. When we replaced our heating system, the contractor told us that worst mistake we could make was to use a cheaper filter. May save us money up front but would cost us more in the long run. After changing to a pleated, more expensive filter, I couldn't believe the difference in our house. I don't dust nearly as often as I used to! It has made a remarkable difference.

Not running your AC for 2 weeks and ending up with less dust should be a big clue to you that your AC filter is NOT trapping the dust. By being gone and not going in and out of your house, less dust is being moved around. When you are home and you are going in and out, doing laundry, blah blah blah, you are making dust and most generally, a good filter will help control this!

We haven't ever cleaned our ducts and neither did the PO(we have lived here 12 years and they lived here 13) and our house is over 110 yrs old so I am not sure that dirty ducts are your problem as much as not using the correct filter.

Duct cleaning is a waste of money. Any loose dust in the ducts is going to get blown out into the room on the airstream whenever the furance fan comes on. That which is stuck to the air piping is just that, stuck and not going anywhere. If you were using a proper furnace air filter you would have less dust. I'd suggest the 3M Filtrete Micro Allergen and they're on sale right now at Target for $8.99 each. And they have a good rep for not restricting airflow per CR. Bite the bullet and go buy 4 of them to do you the year.

Happs,
I find myself in the same situation as you do. The dust in my home is unbearable. When I originally put my heating/air conditioning unit in, I was told to use special pleated air filter that would be good for 90 days and cost approximately $45 each. I found myself replacing them every 1-2 weeks and at that price it was ridiculous. So I started using the less expensive filters and of course the dust hasn't gotten better but it hasn't gotten worse either. I was just recently told by a commercial A/C and heating specialist, that it is very possible the return in my attic may have been put in backwards which would mean that dust is being blown into the house instead of sucked out by the return. He said it is an easy mistake to make and easy to fix -- so that will be my next attempt at fixing this problem. In addition, I will be having my attic completely cleaned out to get rid of all the very old insulation and replaced by new. I'll keep you posted.
Having the ducts cleaned is a waste of time and money. Replacing the expensive filters 1-3 times a week is a waste also. Unless we can get to the actual root of the problem,I really don't imagine being able to fix it completely.

We use the 3M Filtrete filters also. They don't cost anywhere near $45 each!! I am not sure what store my DH now gets them at but he buys them in pkgs of 3... and they are very reasonable for the job they do!

If you are replacing your filter 1-3 times a week, you definitely have a bigger issue going on than dust. Like I said, we have a house over 110 years and have years and years of dust and dirt in the ducts, walls, etc and we don't have enough dirt to even consider changing ours more than every couple of months.

skyned said; I was just recently told by a commercial A/C and heating specialist, that it is very possible the return in my attic may have been put in backwards which would mean that dust is being blown into the house instead of sucked out by the return.

Should be easy to tell by looking at which side of a dirty filter the dust is on.

I started using the $15 3m UltaAllergen filters about every 3 months and those work well combined with a couple of the larger sears hepa filters I picked up off ebay, which their pleated filters can be washed/rinsed easily,(even thought they dont tell you that) and have almost zero dust. But it does cost me some extra on the power bill.

Plan on making an adapter to use the 3m 4" deep media filters on the a/c which cost about $35 each and supposedly are good for about a year.

Right now with nice weather and open windows, no filtering going on and my laptop is getting dusty pretty quick. Dust free computing is important ;) Plus sure do sleep better!