Step 9 - Position Power Exhaust; Barometric Relief Damper Hood; Step 10 - Install Accessories - Carrier 50EJQ Installation, Start-Up And Service Instructions Manual

C 7 4 0 0
A 1 0 0 4
HH57AC078
ENTHALPY SENSOR
(USED WITH ENTHALPY
CONTROL FOR DIFFERENTIAL
ENTHALPY OPERATION)
Fig. 26 — Differential Enthalpy Control and Sensor
Fig. 27 — Wire Connections for Solid-State
Enthalpy Control (HH57AC077)
NOTE: Economizer operation can also be disabled by dis-
connecting the OAT. This is not recommended due to
the fact that Unoccupied Free Cooling, IAQ Purge, and Low
Ambient Fan Cycle Control are also disabled. An OAT fail-
ure alarm will also be issued.
Step 9 — Position Power Exhaust/Barometric
Relief Damper Hood —
been made and adjusted at the factory. The power exhaust
blowers and barometric relief dampers are shipped
assembled and tilted back into the unit for shipping. Brack-
ets and extra screws are shipped in shrink wrap around the
dampers. If ordered, each unit will have 4 power exhaust
blowers and motors or 4 barometric relief dampers.
1. Remove 9 screws holding each damper assembly in
place. See Fig. 30. Each damper assembly is secured with
3 screws on each side and 3 screws along the bottom.
Save screws.
2. Pivot each damper assembly outward until edges of damper
assembly rest against inside wall of unit.
Be careful when tilting blower assembly. Hoods
and blowers are heavy and can cause injury if
dropped.
HH57AC077
ENTHALPY
CONTROL
NOTE: Switches shown in high
enthalpy state. Terminals 2 and
3 close on enthalpy decrease.
All electrical connections have
CONTROL POINT
CONTROL
(APPROX. DEG.)
CURVE
AT 50% RH F (C)
A 73 (23)
B 70 (21)
C 67 (19)
D 63 (17)
RH — Relative Humidity
Fig. 28 — Psychrometric Chart for
Enthalpy Control
3. Secure each damper assembly to unit with 6 screws —
across top (3 screws provided) and bottom (3 screws from
Step 1) of damper.
4. With screws saved from Step 1, install brackets on each
side of damper assembly.
5. Remove tape from damper blades.
Step 10 — Install Accessories —
installed options have been adjusted, install all field-
installed accessories. Refer to the accessory installation
instructions included with each accessory.
MOTORMASTER III INSTALLATION
Install Field-Fabricated Wind Baffles — Wind baffles must
be field-fabricated for all units to ensure proper cooling cycle
operation at low-ambient temperatures. See Fig. 31 for baffle
details. Use 20-gage, galvanized sheet metal, or similar
corrosion-resistant metal for baffles. Use field-supplied screws
to attach baffles to unit. Screws should be
and 5 ⁄ -in. long. Holes for wind baffles are pre-punched in
8
the unit sheet metal.
To avoid damage to the refrigerant coils and electrical
components, use recommended screw sizes only.
The wind baffles attach to flanges formed on the outer sheet
metal of the unit where the condenser coil tube sheets
attach.
Install Controls — Only one Motormaster III control is re-
quired per unit.
Motor — The circuit no. 1 (lead compressor) outdoor-
fan motor (OFM) will need to be changed out in the field to
18
After all the factory-
⁄ -in. diameter
1
4