AC Return Placement And Humidity Entrainment Can Cause Mold Odor In Your AC Ducts

A Accredited Inspection Service, Inc.
6742 Forest Hill Blvd # 271, West Palm Beach, Florida 33413
888-381-6651

www.floridamoldinspectors.us  www.florida-mold-inspection.com

The following info is from two different mold inspections conducted withen three weeks of each other.

The findings on these mold inspections and many other similar mold inspections conducted by us show how proper placement of your AC return is important in detering mold growth and mold odor in your AC ducts.

The inspector inspected the master bathroom as well as the nearby closets where past leakage occurred through a glass block window.The inspector detected two mild distinct odors in the master bathroom that appeared to be related to microbial growth.One of the odors was the result of mold growing in the duct work that services the master bedroom and master bathroom area.In this inspectors experience the specific moldy odor detected in the bathroom AC ducts is almost always created primarily by a type of mold called Cladosporium spherisperium. This is not a toxic mold and does not produce many spores but it creates musty odors that can cause health complaints. This mold like all AC mold needs two things to survive:1)   food2)   moisture.Food is from dust in your ducts so use a good filter in your AC.Moisture is from humidity drawn in through the AC return so control humidity intake.Your AC return is near the bathroom and as a result this return will allow the AC to pull much humidity in from the bathroom after showers and baths, this is called entrainment and this inspector has seen many AC mold problems resulting from of AC returns near humid bathrooms or in other areas where

excessive humidity is drawn in the AC system. Once in the cold ducts the humid air becomes even more humid this causes mold to grow in ducts.We recommend that the AC ducts be cleaned or replaced. If the humidity entrainment problem is not corrected then the mold will return so the AC return will have to be relocated to an area away from the bathroom, consult with your AC contractor about moving it to the master bedroom or master bedroom closet.In addition the bathroom would benefit from additional bathroom ceiling vents to vent humidity out of the bathroom after showers and baths.Above is a photo of your return just a few foot from your bathroom.SPECIFIC AREA FINDINGSAnother odor was detected in the bathroom, this odor was a sewer type odor and likely came from the tubs drain. Typically a P trap in your drain keeps these odors from backing out of the sewer and into our homes, but for some reason stronger than typical odors were coming up from your tubs drain or from the spa jet holes.Start by sanitizing your drain and spa jet pipes with a sanitizer but do not mix chemicals, also keep the drain stopper down when the drain is not in use, hopefully this is all that is needed, if this does not work contact a plumber.Have a plumber review and make any required repairs. This may not be a condition that every plumber is qualified to deal with as it is not the common problem of water simply evaporating from your trap, this may be something different, it may be very simple such as a dirty pipe drain. It may be complex like a missing trap.

SPECIFIC AREA FINDINGS The above mold inspection was conducted in Boca Raton Florida on 1-22-08. The same type of mold odor problem was found 3 weeks later during a mold investigation at a similar luxury home in Wellington Florida near West Palm Beach.   2-12-08 mold inspection  Musty odors were detected, musty or mold odor detection is an important part of any mold investigation because it lets us know that a little mold is present even if it cannot be visually detected. In addition, even when spore levels are low. Minor mold odors were in the following area(s) in the master bedroom when the AC unit was on. The odor detected was typical of that from AC ducts and is not like the odor produced by the many molds that grow in walls. It was detected near the ducts and only when the AC was on.  This was occurring because the AC return is near the master bathroom, this allows the AC to pull humidity into the AC after showers and baths. This humidity condenses in the AC and ducts and allows small amounts of mold to grow in the AC and ducts. This mold inspector has seen this exact same problem in similar homes, and the inspector has seen many mold problems caused under various similar circumstances when AC units pull humidity in, this is called entrainment.  To correct the condition the AC and ducts and main supply plenum for the master bedroom AC will have to be cleaned by a professional who follows NADCA standards and the AC return will have to be moved to a different location in the same zone, a location not so close to the humid bathroom.  Please be aware that this was not a serious mold problem and this does not mean that this is a moldy house, it is a nice house and did not have evidence of a serious mold probelm. This was just your typical minor musty or moldy duct odor and it may not be detected by all persons. Only sensitive persons with allergy or asthma would be affected by such a condition but based on this inspectors experience with this degree of odor some persons can be effects by such odors.

How long after a leak before mold growth starts?

A lot of people ask us how long it takes mold to grow after a recent water
incident; this is the most common question that arises in a persons mind
after a leak.

I am preparing this information for home owners, realtors, and future potential clients 
who are looking for a mold specialist to answer such questions.

If you have the water extracted and the moisture properly dried out by 
professional remediators or carpet drying specialists in the first 24 to 
48 hours after a leak you may likely be ok. It takes mold a 24 to 48 
hours to start to grow under ideal conditions. As you know carpets get 
moldy very quick, many older carpets with dirt as a food source start 
smelling moldy after being wet just a short time. The above refers to small amounts of mold growth, and the mold may only be at the microscopic levels after a few days. It may be a week or two 
before it grows to the extent that it is visible to the naked eye as spots 
on drywall or carpet pads. Of course, mold being a living organism with it’s own agenda
is not going to follow what I say in this bolg and thus their will be exceptions.

Proper drying is important.
What is most important is how fast and how well the flooded areas are 
dried. Many times a person will think that moisture was removed when in 
fact enough moisture was left behind to allow mold to start growing.
If a minor amount of moisture is lingering inside the wall cavities, behind the baseboards, in 
the carpet, or under the carpet padding it will likely be weeks before it 
all dries up, by that time the mold starts forming as visible sports on your walls.
Many mold remediators and carpet cleaning companies will focus efforts on drying the room that flooded and neglect nearby rooms where water flowed hidden inside wall cavities and under carpet or even tile.
Before you realize that dry out was not done properly you may have white, green, or black mold spots showing
up; you may also detect mold odors and  you will likely have mold
capable of causing allergy or asthma reactions in persons who are prone to 
such reactions.

How to properly dry out a property.
Proper drying often involves discarding wet carpets and carpet pads 
because
they trap moisture and hamper drying. If
the flood was extensive, it may be helpful to remove the baseboards 
because these baseboards can trap water and prevent proper drying; in more 
extreme case a few holes can be cut in the walls to allow wet air to 
escape and dry air to enter the wall cavities.
The use of wet vacs to remove standing water, fans to move air, and 
dehumidifiers to dry the air are helpful. Without dehumidifiers to dry the air you are
simply moving wet air with fans
and this is of little or no benefit. If you can dry your air with 
dehumidifiers and maintain humidity levels between 30%RH and 50%RH it will 
help everything else in the area dry faster. Please be advised that I am not a remediator, we at A Accredited Mold Inspection Service, Inc. provide inspections and written reports on mold and moisture problems for you, your attorney, your buyer, or your insurance adjuster. For more info on proper drying consult with a specialist in remediation or carpet drying etc. 

About mold inspections.
It is best to have a mold inspection done by a mold specialist prior to 
doing any work like removing moldy drywall. A mold 
specialist can try and determine the extent of possible mold spread and 
what needs to be done prior to remediation. If more that a very small problem exists it is recommended that a mold removal specialist be called.
We have no conflict of interest and inspect only. We do not do mold 
removal nor do we provide drying services. The fee is $300.00 to $1000.00 
for a mold inspection in the Miami Ft Lauderdale, and West Palm Beach areas. Prices are likely similar in other areas of the nation. An inspection will also include moisture testing, and a detailed 
inspection and written report. In cases where mold may be hidden behind walls it is almost always very 
important to have some samples taken from inside walls to determine if 
hidden mold is in your walls.  If an inspector tells you they will take 
one or two indoor samples from the center of a few rooms your best course 
of action may be to keep calling inspectors until you find one who knows 
to take samples from inside walls when hidden mold from water intrusion is suspected. 

Daryl Watters is president of A Accredited Mold Inspection Service, Inc. He provides home, mold, and indoor air quality investigations in South Florida. He is also the creator of MIR forms designed to aid inspectors in the production of computer generated indoor air quality and mold inspection reports.

For more inspection information visit http://www.floridamoldinspectors.us/ http://www.florida-mold-inspection.com/
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