Mechanical Installation; Duct Collars & Backflow Damper; Ductwork Recommendations - Aprilaire 1750A Installation Instructions Manual

MECHANICAl INSTAllATION

DUCT COllARS & bACKflOW DAMPER
The backflow damper installs on the outlet side of the dehumidifier, using features molded
into the duct collar .
1 . Remove the duct collars and backflow damper from the inner pack .
2 . Place the backflow damper in the collar with the damper pivot shaft resting in the slot in
the collar (see figure 3) .
3 . Position the collar and damper with damper pivot shaft up and install on the outlet panel
using four #8 x 1" field supplied sheet metal screws (see figure 4) . The collar should sit
flush on the outlet panel and secure the backflow damper .
4 . Verify that the damper swings freely by lifting up on the damper and allowing it to
swing closed .
5 . Make sure there are no bends in the ductwork coming off the outlet for a minimum of 4" .
This will ensure that the ductwork will not interfere with backflow damper function
(see figure 5) .
fIGURE 4 – Install Collar with Damper on Outlet

DUCTWORK RECOMMENDATIONS

TAblE 2 – Design Airflows
CFM
External Static Pressure
Amount of 8" Ducting
Notes:
1 . Duct length totals include both inlet and outlet sides .
2 . Elbows, turns, and the static pressure of the HVAC equipment
will affect the airflow through the dehumidifier .
3 . Static Pressure Maximums: 1750A – 0 .8"w .c .
4 . Ductwork to be installed in accordance with SMACNA Standards .
CAUTION
Only install
damper on outlet.
Dehumidifier will
not function if
damper is installed
on inlet.
90-1503
1750A 1770A
275 500
0 .6"w .c . 0 .9"w .c .
70 ft . 100 ft .
1770A – 1 .5"w .c .
fIGURE 3 – Install Damper in Collar
fIGURE 5 – Minimum Ductwork bend Distance
INLET
• W hen ducted to the HVAC supply, the outlet from the dehumidifier
must be located at least 6" downstream of the cooling coil to
prevent outlet air from pulling moisture from the coil .
• T o minimize sound from air movement and vibration, install 5 feet
minimum of flex duct on the inlet and outlet of the dehumidifier .
• U se the least amount of ductwork possible. UL approved, insulated
duct is recommended for all connections .
• I f ventilating, use insulated duct on the dehumidifier inlet duct.
90-1503
4" MIN.
OUTLET
BACKFLOW
DAMPER
90-1503
5