Product data

9
FURNACE AIRFLOWS
0.4
0
840
CFM
1050 1300
EXAMPLE AIRFLOW (CFM versus ESP)
EXTERNAL STATIC PRESSURE (IWC)
FURNACE-DUCT SYSTEMS
GAS HEATING
COOLING
A
B
The airflow performance charts for the
model 58UHV and 58UXV Furnaces
provide nominal airflow in cubic ft per
minute (CFM) versus external static
pressure (ESP) in in. water column
(IWC) for gas heating, cooling, and
heat pump operating modes. Each
model has 2 chart pages: gas heating
and single-speed cooling on the first
page, and 2-speed cooling on the
second page. Gas heating airflow is
shown with dashed lines for HIGH-
GAS HEAT and with dot-dash lines
for LOW-GAS HEAT for all 3 air tem-
perature rise selections. Single-speed
cooling airflow is shown with solid
lines for all 4 size selections. Two-
speed airflow is shown with solid lines
for HIGH-COOLING and with
dot-dash for lines LOW-COOLING
for all 4 size selections.
The curved, dotted lines are furnace-
duct system characteristic curves. Sys-
tem curves can be used to predict the
ESP imposed by a building’s supply-
and return-air duct system at any air-
flow, if a single actual airflow CFM
versus ESP is known.
Example: If CFM and ESP at point A
in example below are known, the CFM
and ESP at point B can be determined
by following the system curve from A
to B. If a point falls between 2 system
curves, follow an imaginary system
curve parallel to and between the
2 system curves.
A96033