CAUSE & ORIGIN INVESTIGATIONS:
COMMERCIAL AND RESIDENTIAL HEATING, COOLING AND AIR CONDITIONING SYSTEMS
https://sites.google.com/site/metropolitanforensics/cause-origin-investigations-commercial-and-residential-heating-cooling-and-air-conditioning-systems
This
time of the year we see a number of cause and origin (C&O) cases regarding
property damages caused by heating, ventilation and air conditioning (HVAC)
systems. Investigation and evaluation of these systems determines the
cause of failure and damage, including whether or not there are sudden and
accidental related causes or long term maintenance and age related conditions
or some other cause. This blog addresses the results of some of the C&O
investigations of these property damage claims.
The
most common HVAC damage claims include: mold growth, water damage and air
quality claims; carbon monoxide damage claims; theft or vandalism; lightning or
power surge damage; improper installation or maintenance;
hail/flood/fire/mechanical failure and other miscellaneous damage claims. This
blog addresses the water damage/mold growth claims.
Mold Growth and
Water Damage Claims
As the air
conditioning system cools a building it produces a large amount of
condensation. Without proper routine maintenance that condensation can
lead to extensive water damage and mold growth. See Figure 1 for what
can grow in the HVAC condensation pan, unless it is regularly maintained by the
insured.
Figure 1.
Mold growth collected from an HVAC drip pan. The insured complained about
odor problems and stained or clogged air registers, but he never inspected the
HVAC unit because it was located in the attic.
Depending on the
humidity level, a central home air conditioner can produce from 5 to 20 gallons
of water day. When the system is working correctly, this condensation drains
off of the coil into a drip pan and is carried by a condensate drain hose into
the sewer system.
Regardless of which
system an AC system uses, almost all blockages occur in the small bend, called
a trap. The trap system always holds a small amount of water that is there to
keep fumes and other objects from backing in to the system. Over time, algae or
gum builds up, the trap becomes clogged, resulting in a plugged condensate
drain line. At other times, we see a kink in the hose, leading into water
damage. Humidifiers can also add too much moisture to a house, leading to
dampness and mold.
If for any reason
(typically because of lack of maintenance or lack of proper operation or
improper installation) the drain or the hoses become clogged, or the system is
producing more water than the drain can handle, the result can be water damage
and mold growth. The HVAC system then becomes a mold supper highway
by recirculating air contaminated with mold spores and other contaminants
throughout the building.
Depending on where
the air handler is located, i.e. a basement, a closet or attic, if the water
over flows it could go unnoticed for a period of time leading to extensive
water damage and mold growth. See Figure 2 for a rusted air handler
located in the crawl space. Lack of accessibility led to lack of
maintenance, corrosion and water damage.
Figure 2.
Rusted and leaked air handler located in the crawl space of this building.
Clogged drain lines
are not the only cause of damage. There are other problems that can contribute
to water damage such as excessive condensation and evaporator coils that are
dirty or over worked. An overworked coil may freeze up and defrost over and over
causing more water than the systems main drain can handle.
Many times, we have
discovered that the HVAC ducts are leaking cold air that mixes with humid air
in the attic or other non-conditioned area of the building; this causes
condensation with subsequent water damage and/or mold growth. At other
times, our inspections have discovered that the air leaks exist on the return
side where the HVAC unit is drawing humid, un-filtered air into the blower and
ducting, resulting in buildup of water and mold growth that in turn is released
into the home. We oftentimes see mold growth on the ceilings around the
air register. What is happening is that the builder often cuts the
drywall opening too large and forgets or not properly seals the gap. The
result is that humid and hot attic air enters the building through these
openings and condenses, providing the moisture needed for mold growth.
Figure 3:
Condensation formed on the exterior of the duct due to system leaks.
In many high rise
constructions we have observed lack of return air ducting due to lack of
space. This led to overworked HVAC systems, resulting in freezing, water
leaks and mold growth. At other times we observed the ducts to be too bent,
causing excessive energy use; the building owner then turned down the
thermostat to compensate for the reduced system efficiency, causing duct
sweating and mold growth. The building tenants complained that they were
“breathing dust and mold”.
Figure 4. This
is an example of a common problem we have seen with air ducts: they are
bent by the installers too much trying to fit them in tight places. This
has led to excessive energy usage, water damage and mold growth.
By far the most
common area of mold growth in an HVAC system is associated with buildup of mold
and dust inside the return duct. The buildup of mold and dust there will
cause an accumulation of the same in the evaporator coils, leading to water
damage and health issues inside the home. Regular maintenance of the air
filters and the ducts will prevent such damage claims.
Figure 5 and
6: Dirty air filter and air duct (Fig. 5) due to lack of cleaning of the
air filters and ducts. This resulted in dirty HVAC coils (Fig. 6),
because there was lack of maintenance of the coils. The coils rusted,
froze up and end up causing water damage to the insured’s property.
Overall, the
overwhelming majority of the property claims could have been avoided with
proper maintenance or replacement/repair of the failing HVAC components.
Metropolitan Engineering, Consulting & Forensics
(MECF)
Providing
Competent, Expert and Objective Investigative Engineering and Consulting
Services
P.O. Box 520
Tenafly, NJ
07670-0520
Tel.: (973)
897-8162
Fax: (973) 810-0440
E-mail: metroforensics@gmail.com
Metropolitan
appreciates your business.
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Metropolitan has
extensive experience assisting in the evaluation of environmental factors. Our
Certified Industrial Hygienists and Registered Professional Engineers have
performed IAQ testing, mold testing, Chinese drywall corrosion investigations,
water source evaluation and remediation design and oversight.
We perform Property
Condition Assessments, Indoor Air Quality Evaluations and Environmental Site
Assessments, including Indoor Air Quality