Bryant IX. Ð Install ALL Accessories, Motormaster I Control Installation 559F180

NOTE: For maximum bene®t of outdoor air, set the enthalpy control to the ``A'' setting. At this setting, when the relative humidity is 50% and the outdoor air is below 74 F, the relay contacts on the sensor will be closed.

9. Reinstall economizer hoods if removed.

IMPORTANT: Be sure all seal strips and RTV sealant are in- tact. A watertight seal to inside of unit must be maintained.

Fig. 20 Ð Outdoor-Air and Return-Air

Enthalpy Sensor

CONTROL CONTROL POINT

CURVE (Approx Deg)

AT 50% RH

A73

B68

C63

D58

RH Ð Relative Humidity

Fig. 21 Ð Psychrometric Chart for Solid-State

Enthalpy Control

B. Differential Enthalpy Control

NOTE: The accessory outdoor-air enthalpy sensor must be installed BEFORE the economizer hoods are installed on the unit or hoods will have to be removed.

1.Remove and discard the factory-installed jumper as- sembly containing the 800-ohm resistor on the econo-

mizer control module (between terminals SR and +. See Fig. 15.

2.Disconnect black wire from economizer control module

terminal SO and blue wire from the OAT (outdoor-air thermostat).

3.Remove OAT and black wire assembly containing the 620-ohm resistor from the outside of the economizer (see Fig. 14).

4.Mount the outdoor-air enthalpy sensor (®rst sensor) to the economizer on the outside of the unit (in the same location from which the OAT was removed) using the 2 screws provided. See Fig. 14.

5.Reconnect the blue wire removed in Step 2 to the en- thalpy sensor terminal +.

6.Cut the violet wire provided to desired length and ter- minate with quick-connect terminal provided. Route the violet wire from the enthalpy sensor terminal S, through the snap bushing, and to the economizer control mod- ule terminal SO.

7.Mount the second enthalpy sensor in the return-air duct (return-air sensor).

8.Route the blue wire (provided) from terminal + on the return-air enthalpy sensor to the economizer control module terminal +.

9.Route the violet wire (provided) from terminal S on the return-air enthalpy sensor to the economizer control module terminal SR.

10.Turn changeover set point dial clockwise past the ``D'' setting, or the control will not operate on a differen- tial. See Fig. 15.

11.Reinstall economizer hood if removed.

IMPORTANT: Be sure all seal strips and RTV sealant are in- tact. A watertight seal to inside of unit must be maintained.

IX. STEP 9 Ð INSTALL ALL ACCESSORIES

After all the factory-installed options have been adjusted, in- stall all ®eld-installed accessories. Refer to the accessory in- stallation instructions included with each accessory.

A. Motormaster I Control Installation (559F180 and 216)

Install Field-Fabricated Wind Baffles

Wind baffles must be ®eld-fabricated for all units to ensure proper cooling cycle operation at low ambient temperatures. See Fig. 22 for baffle details. Use 20-gage, galvanized sheet metal, or similar corrosion-resistant metal for baffles. Use ®eld- supplied screws to attach baffles to unit. Screws should be 1¤4-in. diameter and 5¤8-in. long. Drill required screw holes for mounting baffles.

CAUTION: To avoid damage to the refrigerant coils and electrical components, use recommended screw sizes only. Use care when drilling holes.

Install Motormaster I Controls

Only one Motormaster I control is required per unit. The Motor- master I control must be used in conjunction with the Acces- sory 0° F Low Ambient Kit (purchased separately). The Motormaster I device controls outdoor fan no. 1 while out- door fans no. 2 and 3 are sequenced off by the Accessory 0° F Low Ambient Kit.

Accessory 0° F Low Ambient Kit Ð Install the Accessory 0° F Low Ambient Kit per instruction supplied with accessory.

Motor Mount Ð To ensure proper fan height, replace the ex- isting motor mount with the new motor mount provided with accessory.

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