Air Quality Question By Jeffrey Dach
The previous occupants of the apt unit apparently did not change the
air conditioning filter after an extensive dry wall build out. We
went ahead and replaced the old AC filter which was caked with dry
wall dust .
In addition, fine particles of dry wall dust are visible coming out of
the air vents when the air is on. These are most visible on reflective
metal surfaces which show the fine particles that have accumulated
when viewed at an angle. Options here are 1) place additional filters
on the A/C vents to stop the particles from coming out
2) Some type of duct cleaning and sealing procedure.to remove the
debris which spilled out into the duct work after the dry wall build
Any suggestions would be apreciated. regards jeffrey dach
Did you replace the filter with a good one, like a 3M? If not, get
a couple good ones.
Run the A/C unit is "Fan Mode", do a surface clean up with barely damp
cloths throughout the entire apt.
Vacuum carpets, sweep & damp mop hard floors.
If the apt is small, you can probably take off the duct registers
and do a passable job of duct cleaning with your shop vac faster
than it takes to research a duct cleaning service & wait for them to
After a day or two take a look at the filter for dust build up.
Also check for continued dust accumulation on flat surfaces
I've done demolition where I didn't put up enough (or any plastic),
made a dusty mess in the adjacent rooms. :(
Damp wipe down, vacuuming carpet, moping floors and new furnace filter
had the place cleaned up before my wife got home (a day or two).
I've never done a duct cleaning and once the place is clean, dust
accumulation is back to "normal".
If it's that bad, I'd go with a duct cleaning and inspection of the
IF the coils are covered in it, which would seem likely, especially if
the AC was
in use, making them wet, then it will reduce the performance of the
Also, consider the filter possibilities. The choices will be limited
by the existing
filter holder, ie you can't put a 5" filter if all you have is a 1"
space. If you have
someone check the coils, ask them about options for either a media air
or electronic. When considering filters, don';t just look at MERV
rating, which is
a mistake many people do. MERV tells you how small a particle it can
The other critical factor is how much resistance the
filter presents to air flow. A high MERV filter without enough
surface area can
significantly restrict the air flow.
Epilogue to our drywall dust problem in the A/C system:
After researching all the options and consulting with 5 different A/C
companies who gave five differing opinions, we decided to clean the
entire system, the A/C ducts, air handler unit, coils and blower. We
decided not to dismantle the coils or blower. Instead we opted for
Duct Doctor which did not require dismantling the unit. In my
opinion, Duct Doctor has the most advanced equipment, best training
and best procedure technique which is described here:
They certainly have the largest truck. The Duct Doctor truck is
unique to the franchise, and is actually a massive vacuum cleaner.
The tech cuts a circular hole in the duct work near the air handler
unit and places a large bore (10-12 inch diameter) vacuum hose
creating reverse air flow from the A/C register to the vacuum hose.
At the register end, a tech uses a unique spaghetti like oscillating
rubber device driven by compressed air which gently knocks the dust
and dirt off the walls of the ducts captured by the reverse air flow,
and sucked back into the truck which has large filters to catch all
the debris. They came in last week with the truck and did a very
complete job cleaning of the entire A/C system from front to back
including the supply ducts, and the coils and blower. I would use
them again, and they are far preferable to the hundreds of smaller
companies that are essentially ineffective. Note: I have no financial
interest or financial relationship with the Duct Doctor Company.
Simple duct cleaning is good, but you may have problems beyond that,
as Stormy mentions. The gypsum in wall board (Ca SO4) could be
corrosive to aluminum under some conditions. Getting rid of all of it
might be best done by a company like ServPro that specializes in after
disaster cleanups. They (or a similar company) should have better
equipment, personnel, and know-how that should be most cost effective
in the long run.
Your air filter is there to protect the equipment, not your lungs.
(that's why it's on the return rather than supply)
If dry wall dust is coming out of the vents, the filter failed. There
must be dust all over the coils.
I wouldn't worry about cleaning the ducts. There can't be much there,
it does no harm, and will shortly blow out.
But the stuff on your coil is stuck there and harming the
performance. I think you need to get a good technician to take a look
and clean the coils as needed.
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