Heavenly View = Hellish Mold Problem

January 6, 2008

In coastal Florida if your doors and windows are weathered and leak excessive amounts of humid air, a heavenly ocean view can allow for conditions that result in a hellish AC mold problem.

The information in this blog give a text book example of how warm tropical ocean breezes infiltrating into an AC system can result in humidity, condensation, and mold in and around your AC ducts and registers.

This information is from a Broward county Ft Lauderdale mold inspection that took place on 11-8-07.

Client moved in as a renter 7 days prior to this inspection. Client reported that his fiancee moved into the property with him and enjoyed the property, but because of severe allergic reactions that occurred while in the property she moved out after just one day.

Client requested this investigation to help determine if mold or other similar bio-allergen may be at the property that may account for her complaints.

The inspector observed that mold was a problem in the AC unit and in the AC ducts at the property, this mold requires food and moisture to live.

As is almost always the case in moldy AC units the mold in the AC and ducts received it’s moisture from elevated humidity and from condensation in the AC and ducts. It recieves it’s food from dust that bypasses the filter.

Humidity entered the AC and ducts by first entering from outside.

The view outside the unit is excellent, it is this high ocean front vantage point combined with leaky sliding glass doors that provided the moist breezes that allowed this mold problem to occur.

In addition the master bathroom is not vented to the exterior, whenever someone takes a shower that shower steam can enter the AC unit and form condensation as well. Either the non vented bathroom, or the leaky sliding glass doors overlooking the ocean alone would have been enough to cause a problem.

The sliding glass doors did not fit air tight, in fact the inspector could feel a strong ocean breeze blowing through the sliding glass doors from 2 foot away even though the doors were closed as tight as possible. Humidity blowing indoors from outdoors often results in mold and humidity problems, this is sometimes called the paston effect.

Gaps in these old doors allow much moist ocean air in.

Mold requires not just moisture but also food. The mold in the AC system and ducts at this property received it’s food from dust as does most AC mold.

In the above photo you can see a hole where dusty air can bypass the AC filters and enter the AC unit.

Dust can also by pass the filters because they are very low quality and do not fit properly, dust goes around the filters.

AC mold and condinsation problems

During the mold inspection the inspector observed that condensation sometimes forms on the AC registers.

The inspector observed the water stains left behind by condensation dripping off the AC registers. Note that condensation forming on AC registers is not normal, this condition indicates that so much humidity was present in the property that it condensed out on cold metal & glass registers that typically reach around 60F or so when in operation. The natural progression of this condition is for mold and condensation and water damage to form on the drywall around the register if the humidity problem is not corrected.

Elevated humidity and condensation inside ducts and AC units causes mold to grow in ducts and AC units just as it developed on the visible sections of the outside of registers. It is common for homes with mold on registers to have much more mold inside the ducts and AC unit because the interior of the ducts and AC is much colder thus much wetter than the surfaces of the registers, also the interior is duster thus has more food for mold growth.

Because mold in the AC unit has better growth conditions than mold on the registers it exhibits dimorphism. In other words these mold look different in different environments. Most of the mold in the AC unit is the exact same type that formed on the registers but being in a more healthy environment with more food and water inside the AC unit it grows more thick and lush and sometimes takes on a fluffy grey velvety appearance. In each case the mold is cladosporium sphearisperium.

Mold inside AC units does not produce many spores but instead grows and reproduce more vegetatively. This is significant because mold in AC units do not produce many spores but will grow profusely feeding off condensation and dust. AC mold by products are not lots of spores but are Mvoc’s, these Mvoc’s are foul smelling moldy odors that are released by the molds and this is why the clients fiancee got sick.

It is a well accepted fact that Mvoc’s or mold odors produced by AC type molds and other molds can and very often do result in strong allergy like reactions and irritations.

In this inspectors experience AC units that grow mold in the amounts seen at this property very often produce health complaints in building occupants.

In conclusion the AC unit’s ducts, registers, blower fan, evaporator coil, condensation pan, wires, and most of all interior fiberglass insulation are infested with more than normal amounts of mold growth, and the grow is extremely consistent with conditions that this inspector has observed to result in both odors and health complaints.

Because the AC unit is extremely contaminated with mold and produces strong foul odors it is recommended that the unit be professionally cleaned in accordance with NADCA standards, or the unit should simply be replaced because cleaning the unit will likely result in damage to the very rusty pan and coils.

Because of the amount of contamination in the ducts it is recommended that the ducts be replaced. Cleaning fiberglass ducts is not recommended they are supposed to be replaced if contaminated. Note that the interior of all sections of the ducts will not be visibly moldy but expect mold contamination to have spread to many different duct sections.

The following photos are of mold on AC registers, in the AC ducts, and in the AC unit at this property. Note that the ducts should all be bright yellow and resemble a tennis ball in color and texture.

AC duct mold

Typical cladosporium mold colonies on an AC register. Nearly all registers at the property were visibly moldy.

black air conditioner mold spots

Close up of cladosporium mold colonies on the AC register.

HVAC mold

Close up of mold in the duct, this duct used to be yellow.

Mold in the AC unit. The white mold is likely pen asp and the grey mold is cladosporium sphearisperium, it is the same type of mold observed as black spots on the register, but it looks different inside the AC because of different environmental conditions inside the AC.

Mold on the AC unit panel insulation.

Fluffy grey cladosporium sphearisperium mold on the blower fan inside the AC, this is very common.

About the Author:
Daryl Watters is a certified indoor environmentalist CIE # 1952 who provides mold testing and IAQ consultation services in South East Florida.


One Response to “Heavenly View = Hellish Mold Problem”

  1. Bob Grimes said

    Dear Mr.Watters,
    I found your report while searching the net for information on a specific model Air Handler.Let me say thank you for your report. I am working on my sisters home here in NW Florida. I am not an AC Guy. I have been in construction both new and remodeling for over 30 years. I had planned to replace the Flexible ductwork but had not thought about the plenum. The fan motor on the air handler looked almost exactly the same as your picture. I could go on, BUT, THANKS.
    Best Regards,
    Bob Grimes

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