38 | February 2019
Preparing for Occupancy: Before new occupants move
in, an HVAC system should be professionally cleaned, in-
cluding the ducts, blower cabinet, blower, and cooling coils.
Radiators and baseboard heating convectors should also
be HEPA vacuumed and if necessary, treated with steam
from a steam-vapor machine.
Final words: Good practices while installing mechanical
systems can help prevent many IAQ problems down the line.
I have found in my many investigations of sick build-
ings that mechanical systems are often the culprits due
to poor design, inadequate filtration and sloppy main-
tenance.
Founder and Principal Scientist of May Indoor Air Investiga-
tions LLC in Tyngsborough, MA (www.mayindoorair.com), Jef-
frey C. May combines his education as an organic chemist and
his over twenty-five years of experience investigating building
problems to specialize in indoor air quality (IAQ). He is a former
Adjunct Faculty Member in the Department of Work Environ-
ment at University of Massachusetts Lowell, and is author or
co-author of four books on indoor air quality (published by The
Johns Hopkins University Press), including My House is Killing
Me: The Home Guide for Families with Allergies and Asthma.
Jeff is a nationally recognized speaker at annual conferences
for the IAQ Association and the Maine IAQ Council, among
others. He is a Council-Certified Microbial Consultant (ACAC)
and a Certified IAQ Professional (AEE), and is licensed in the
NH and FL as a mold inspector/assessor. Jeff holds a B.A.
from Columbia College (chemistry) and an M.A. from Harvard
University (organic chemistry).
See http://www.mayindoorair.com for details about Jeff's
company's services, and www.myhouseiskillingme.com for
more information about Jeff's publications and work. You can
contact Jeff at jeff@mayindoorair.com or call 978-649-1055.
Winter condensation in an attic A/C trunk duct due to bedroom
humidifier use May Indoor Air Investigations LLC
ERVs and HRVs
New homes are tight homes, so many of them have ERVs
or HRVs. Such units collect biodegradable dust and usually
lack adequate filtration and maintenance.
Moldy, filthy outside-air filter in ERV
May Indoor Air Investigations LLC
Most of the ERVs and HRVs that I have opened up
had mold problems. Filtration must be upgraded on both
the outside-air intake duct and the house-air intake duct of
the unit. I recommend removing the interior filters and us-
ing in-line Fantech FB6 filters but with MERV-8 rather than
MERV-12 filters. Since any ERV/HRV may run continuous-
ly, frequent filter changes and regular maintenance will be
needed. Such units should also have drainage to accom-
modate condensation.
Our book The Mold Survival
Guide: For Your Home and
for Your Health contains
guidance for both home
occupants and building
professionals. Part III
focuses on mold removal
and remediation.
Available on amazon.com
