The best way to keep the dust out of the ducts is to keep your system off during construction. Without the return air pulling air into the system.
One of the best ways to know if your ducts or vents need to be cleaned is to just check them. Your eyes will be able to check for indications of mold, dust or pollen buildup in the ducts and vents. You might also be able to smell the presence of mold, which would be a clear indicator there is some in the ducts or vents. Ductwork will have some buildup of dust, since the return registrars pull air back in. If a company tells you that you have mold in your air ducts, that could be a red flag. I recommend sending that company on its way before any work is done and having a qualified mold testing firm out to your home to verify if in fact mold is present.  Cleaning air ducts makes a lot of sense, at least in theory. Because dust gradually accumulates on virtually every surface, doesn’t it stand to reason that it would build up to an intolerable degree in the mostly untended HVAC ductwork that runs throughout your home? Yes, air ducts get dusty. Your furnace or air conditioning filters trap a high percentage of particles in the air, preventing them from entering the ductwork. Surely, that’s a reason to clean or replace your HVAC filters on a regular basis, but it’s not a strong argument for taking any further action. 2. The air coming out of the supply vents will be cleaned air. If you have a specific area in a room that you want extra air cleaning then utilize a good portable unit with a powerful enough fan to circulate some air in that area, if you can put up with the noise. . If your filter is in a grille going into the cavity under your unit in a closet and the cavity is not sealed then you can be drawing air from the attic. This is not a good thing. It will get your system dirty fast and will cost you a lot on your cooling bills. The picture here is of an unsealed return air cavity. When a professional cleaner comes into your home to clean air ducts and vents, that means they will clean all the different elements in the HVAC system, including the supply and return air ducts, grilles, diffusers, exchangers, heating & cooling coils, drip pans, fans and the air handling unit. You might also be able to smell the presence of mold, which would be a clear indicator there is some in the ducts or vents. Ductwork will have some buildup of dust, since the return registrars pull air back in. This will permit you slide the vent off of the air duct. Fill your kitchen sink with warm water and add enough liquid dish soap or detergent to make the water sudsy. Immerse the air vent into the soapy water and scrub it from top to bottom with a soft brush or sponge. Be sure to get between the slats of the air vent. If necessary, use cotton swabs to clean the slats. Rinse the air vent and allow it to air dry. As the air vent is drying, take your vacuum back to the air duct and vacuum it out with the brush or crevice attachment, reaching as far into the duct as you can. Replace the air vent once it has dried. If the unit turns on while you’re cleaning the vents, it may cause more dust to spread throughout the house. Vacuum the air vent using a brush and/or crevice attachment on the end of the vacuum hose. If necessary, use a stepladder or chair in order to reach the air vent. Examine the air vent. Professional duct cleaning services use specialized blowers, vacuums, and brushes to clean out the supply, intake, and return ducts throughout your home. Duct cleaning should also involve a thorough cleaning of the air handler, registers, grilles, fans, motors, housings, and coils of the HVAC system. There’s no research at present proving that routine duct cleaning improves the air quality or reduces dust in your home. The best way to keep the dust out of the ducts is to keep your system off during construction. Without the return air pulling air into the system, you don't have to worry about the supply side. Shut off the central heat and air unit if it is warm enough. Uncovered vents will draw the sanding dust through the duct work, and spread it throughout the entire house. Utilize Available Tools. Attach a drywall vacuum sander to a shop vacuum to eliminate the majority of airborne dust. by HowStuffWorks.com Contributors. One of the best ways to ensure that the air in your home is clean is to clean your air vents. The air ducts in your house contain millions of particles of dust, hair, dirt, pollen, spider webs and other allergens [source: Alpine Air Duct ]. Here's what to do: 1  Turn off the power connected to the heating and air conditioning system [source: Reliable Remodeler 2  ]. Unscrew the air duct covers or grilles from the walls. 3  Use your brush to clean the grates thoroughly. 4  If they're very dusty and grimy, you may want to use soap and water to make them gleam.
http://www.homeadvisor.com/cost/cleaning-services/clean-ducts-and-vents/ http://articles.courant.com/2013-03-29/business/hc-ls-air-duct-cleaning-20130323_1_duct-mold-equipment http://www.bobvila.com/articles/cleaning-air-ducts/ http://www.ccacac.com/equipment-2/filters/dust-problems/ http://www.homeadvisor.com/cost/cleaning-services/clean-ducts-and-vents/ http://www.ehow.com/how_7733923_clean-dust-out-air-vents.html http://www.todayshomeowner.com/hvac-duct-cleaning-scam-or-worth-it/ http://answers.angieslist.com/How-I-drywall-dust-air-ducts-q23761.aspx http://home.howstuffworks.com/home-improvement/household-hints-tips/cleaning-organizing/how-to-clean-air-vents-in-your-house.htm
how to get dust out of air ducts