TAB Journal Fall 2020 - 16

It should also be noted that the flooding
of HVAC air handling equipment,
cooling coil condensate drain pans can
lead to stopped-up condensate drains,
which in turn leads to the pooling of
water within the equipment. Pooled
condensate drain water will become
stagnant and ultimately result in
ideal petri dish conditions within the
equipment for cultivating potentially
dangerous organic growth such as
Legionella. 1
6.	Greatly increased potential for
organic growth in HVAC air handling
equipment cooling coil sections, as
well as all sections located downstream
of the cooling coil such as the supply
air fan section and the discharge air
plenum section.
1

The Occupational Safety and Health
Administration website Legionnaires'
Disease page indicates that " improperly
draining condensate pans may produce
the ideal tepid conditions that can
encourage microbial and fungal
growth. "

Wintertime Operation
1.	Lower HVAC air handling equipment
discharge air conditions, and lower
(i.e. dryer) space relative humidity
levels in the areas served by this
equipment.

2.	Increased complaints from facility
occupants concerning cold space
temperatures and very dry air resulting
in space static electricity issues.
3.	Greatly increased potential for freezing
the HVAC air handling equipment
cooling and/or heating coils due to
the significantly lower mixed air
temperatures entering the equipment.
Typical Scenario Example
By way of example, a typical
commercial 20-ton HVAC air
conditioning unit (floor-mounted,
ceiling-suspended or rooftopmounted equipment) sized for a typical
minimum outdoor airflow of 20 percent
of the equipment's total airflow, has the
following typical operating parameters:
1.	Unit cooling capacity = 20 tons or
240,000 British thermal units per hour
(BTUH) (Note: 1000 BTUH = 1 MBH).
2.	Unit heating capacity = 521 MBH.
3.	Unit nominal rated airflow = 8,000
CFM.
4.	Unit outdoor airflow = 1,600 CFM (i.e.
20 percent).
5.	Typical HVAC equipment OA entering
temperature & humidity conditions
during the cooling season: 80°F dry
bulb (DB)/67°F wet bulb (WB)/50

percent relative humidity. (Note:
temperature units = °F = degrees
Fahrenheit, humidity units = percent).
6.	Typical HVAC equipment OA entering
conditions during the heating season:
10°F DB.
7.	 Typical indoor space conditions in an
area served by HVAC equipment: 75°F
DB/50 percent relative humidity.
8.	Typical cooling coil discharge
air conditions during the cooling
season: 55°F DB/53.75°F WB.
9.	 Typical heating coil discharge air
conditions during the heating season:
122°F DB.
The percent of this HVAC unit's 20-ton
cooling capacity represented by the
minimum OA airflow load component is
approximately 5.42 tons, or approximately
27.1 percent of the unit's total cooling
capacity. Every incremental increase of
100 CFM in the amount of OA handled by
this unit adds approximately 4,000 BTUH
of additional cooling load or roughly a
third of a ton.
If service personnel were to simply
increase the amount of OA ventilation
airflow on this typical HVAC air
conditioning unit to say, 50 percent of
total unit airflow (i.e. increasing OA
airflow from 1,600 CFM to 4,000 CFM),

Need a Better

Test & Balance Spec?
AABC CAN HELP!
■	 Specify for Independence

■	 Recommended, achievable tolerances

■	 Detailed contractor
responsibilities to ensure
readiness for T&B

■	 Detailed procedural requirements
■	 AIA format, MasterSpec approved

For more information: www.aabc.com/specifications
Email headquarters@aabc.com, or call 202-737-0202
16

TAB Journal Fall 2020


http://www.aabc.com/specifications

TAB Journal Fall 2020

Table of Contents for the Digital Edition of TAB Journal Fall 2020

TAB Journal Fall 2020 - Cover1
TAB Journal Fall 2020 - Cover2
TAB Journal Fall 2020 - 1
TAB Journal Fall 2020 - 2
TAB Journal Fall 2020 - 3
TAB Journal Fall 2020 - 4
TAB Journal Fall 2020 - 5
TAB Journal Fall 2020 - 6
TAB Journal Fall 2020 - 7
TAB Journal Fall 2020 - 8
TAB Journal Fall 2020 - 9
TAB Journal Fall 2020 - 10
TAB Journal Fall 2020 - 11
TAB Journal Fall 2020 - 12
TAB Journal Fall 2020 - 13
TAB Journal Fall 2020 - 14
TAB Journal Fall 2020 - 15
TAB Journal Fall 2020 - 16
TAB Journal Fall 2020 - 17
TAB Journal Fall 2020 - 18
TAB Journal Fall 2020 - 19
TAB Journal Fall 2020 - 20
TAB Journal Fall 2020 - Cover3
TAB Journal Fall 2020 - Cover4
https://www.nxtbook.com/ygsreprints/AABC/tab-journal-winter-2021
https://www.nxtbook.com/ygsreprints/AABC/G122399AABC_Fall2020
https://www.nxtbook.com/ygsreprints/AABC/G120138AABC_Summer2020
https://www.nxtbook.com/ygsreprints/AABC/G118248AABC_Spring2020
https://www.nxtbook.com/ygsreprints/AABC/G116302AABC_Winter2020
https://www.nxtbook.com/ygsreprints/AABC/G114573_AABC_Fall2019
https://www.nxtbook.com/ygsreprints/AABC/G111085_tab_summer2019
https://www.nxtbook.com/ygsreprints/AABC/g108931_tab_spring2019
https://www.nxtbook.com/ygsreprints/AABC/g104992_tab_winter2019
https://www.nxtbook.com/ygsreprints/AABC/g100221_tab_fall2018
https://www.nxtbook.com/ygsreprints/AABC/g97743_tab_summer2018
https://www.nxtbook.com/ygsreprints/AABC/g94804_tab_spring2018
https://www.nxtbook.com/ygsreprints/AABC/g91043_tab_winter2018
https://www.nxtbook.com/ygsreprints/AABC/g86727_tab_fall2017
https://www.nxtbook.com/ygsreprints/AABC/g81312_tab_summer17
https://www.nxtbook.com/ygsreprints/AABC/g78003_tab_spring17
https://www.nxtbook.com/ygsreprints/AABC/g73432_tab_winter17
https://www.nxtbook.com/ygsreprints/AABC/g7002_tba_fall2016
https://www.nxtbook.com/ygsreprints/AABC/g65897_tab_summer2016
https://www.nxtbook.com/ygsreprints/AABC/g62758_tab_spring16
https://www.nxtbook.com/ygsreprints/AABC/tab_winter2016
https://www.nxtbook.com/ygsreprints/AABC/tab_fall2015
https://www.nxtbook.com/ygsreprints/AABC/tab_summer2015
https://www.nxtbook.com/ygsreprints/AABC/g50853_aabc_spring2015
https://www.nxtbook.com/ygsreprints/AABC/g48663_aabc_winter2015
https://www.nxtbook.com/ygsreprints/AABC/g46741_aabc_fall2014
https://www.nxtbook.com/ygsreprints/AABC/g43965_aabc_summer2014
https://www.nxtbook.com/ygsreprints/AABC/g42323_aabc_spring2014
https://www.nxtbook.com/ygsreprints/AABC/g40447_aabc_winter2014
https://www.nxtbook.com/ygsreprints/AABC/g38793_aabc_fall2013
https://www.nxtbook.com/ygsreprints/AABC/g36202_aabc_summer2013
https://www.nxtbook.com/ygsreprints/AABC/g34728_aabc_tabspring2013
https://www.nxtbook.com/ygsreprints/AABC/g32884_aabc_tab-winter2013
https://www.nxtbook.com/ygsreprints/AABC/g30873_aabc_tabjournal_fall2012
https://www.nxtbook.com/ygsreprints/AABC/g28877_aabc_tabjournal_summer2012_2
https://www.nxtbook.com/ygsreprints/AABC/g25452aabc_tabspring12
https://www.nxtbook.com/ygsreprints/AABC/g23327aabc_fall_2011
https://www.nxtbook.com/ygsreprints/AABC/g21694aabc_summer11_final
https://www.nxtbook.com/ygsreprints/AABC/g19912nxtbk
https://www.nxtbook.com/ygsreprints/AABC/g19105_aabc_tabjournalwinter11
https://www.nxtbook.com/ygsreprints/AABC/AABC/p17871_aabc_fall10
https://www.nxtbook.com/ygsreprints/AABC/g16041aabc_tabjournal
https://www.nxtbookmedia.com