036-21540-001-A-0503
18
Unitary Products Group
LOW AMBIENT DAMPER INSTALLATION
If unit operation is required at outdoor ambient below
60
°
F, the optional Low Ambient Damper kit should be
installed to maintain acceptable condensing pressure.
The damper is installed directly onto the discharge duct
connection as illustrated. The damper is controlled via
a refrigerant pressure actuator. Two different actuator
mounting arrangements are used, depending on the
size of the damper. Appropriate mounting hardware for
the actuator is provided with each kit. The pressure
actuator is connected to the liquid line access fitting
through a 1/4 in. copper tube. Attach the tubing using
flare nuts at each end. A routing hole is provided in the
condenser corner panel near the actuator mounting
position. Purge the 1/4-in. sensing line by loosening the
flare nut at the actuator until liquid refrigerant is
observed leaking from the fitting. Tighten the flare nuts
securely.
NOTE:
On dual and triple compressor units, the actuator
MUST be connected to the #1 circuit liquid line fit-
ting. Connection to the second or third stage refrig-
erant circuit will result in system malfunction.
A solid-state timer(s) is provided with the damper kit.
The timer will bypass the low-pressure switch during
compressor start-up. The time delay allows the con-
densing pressure to rise sufficiently for refrigerant flow
through the evaporator to be established. The 8-25 ton
units require a timer to be installed on each compres-
sor circuit.
Mount the timer(s) in the condenser electrical panel.
Mounting holes are provided near the lockout relays
(R1, R2). Connect the timers into the compressor con-
trol circuit as shown. The wire splice between the LPC
and HPC switches is accessible inside the electrical
panel, in the low voltage section of the enclosure.
Test run the unit, and confirm proper operation. The
damper should be fully closed when condensing pres-
sure is below 165 psig, and should be fully open at con-
densing pressures of 250 psig and above.
FIGURE 9 - LOW AMBIENT DAMPER INSTALLATION
