Fresh Outside Air is a
Good Thing - By Paul Burns, ASCS
We all know that providing fresh outside air/makeup
air is a code in commercial and industrial HVAC systems and a good
thing in residential. Unfortunately this air is very often not
filtered and can bring in pollutants, fungus, dirt and mold spores
that undo all of our good hard work. The main “evil doer” carried
in through the fresh air makeup is particulate matter. The EPA
defines particulate matter as “any substance that is light enough to
be suspended in the air”. Other pollutants such as Radon are
typically not a problem in the Houston metropolitan area and are
much more difficult to remove from the air.
No discussion of good fresh air makeup quality would
be worth reading without the mention that the location the fresh air
makeup intake is placed will play a very large role in the quality
of air brought into the HVAC system. A fresh air makeup intake
should not be placed in locations where carbon monoxide (from
parking garages, near commercial gas clothes dry vents, above
restaurant kitchen exhausts, etc.) and other noxious fumes, gases
and large quantities of particulate matter will be drawn into the
HVAC system.
Ideally the filter would be located at the fresh air
makeup intake and would consist of a prefilter to catch large
particles, birds, leaves, etc. and a primary filter with the highest
MERV rating the HVAC system can handle with a minimum of MERV 7.
In summary, some measures to consider when adding
fresh air to the ventilation system are:
-
Outside air should pass through a filter that has
as high a MERV value as possible within the HVAC system's design
capability
-
Install thin weather stripping around the return
duct housing to create a gasket at the duct housing/filter frame
interface to prevent bypass or blow-buy
-
Keep outside air intakes away from any type of
exhaust system
-
Use prefilters
to capture coarse dusts and allow the final filter to be exposed
to smaller concentrations of finer dusts
-
Change filters when they become dirty and
impacted to prevent damage or overloading of the blower motors.
Performing these tasks when adding outside or fresh
air into the HVAC system provides your customers with the best
possible indoor air quality and helps prevent potential customer
complaints.
Commercial
Air Duct Cleaning in Texas
