Bryant XI. Install ALL Accessories, Motormaster I Control Installation 581A155 and 180 Only

	CONTROL
CONTROL	POINT
CURVE	(Approx Deg)
	AT 50% RH
A	73
B	68
C	63
D	58

RH — Relative Humidity

Fig. 24 — 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 assembly containing the 800-ohm resistor on the

economizer control module (between terminals SR and +). See Fig. 18.

2.Disconnect black wire from economizer control mod-

ule 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. 17).

4.Mount the outdoor-air enthalpy sensor (first 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. 17.

5.Reconnect the blue wire removed in Step 2 to the enthalpy sensor terminal +.

6.Cut the violet wire provided to desired length and terminate with quick-connect terminal provided. Route the violet wire from the enthalpy sensor termi- nal S, through the snap bushing, and to the econo- mizer control module 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 con- trol 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. 18.

11. Reinstall economizer hood if removed.

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

XI. STEP 11 — INSTALL ALL ACCESSORIES

After all the factory-installed options have been adjusted, install all field-installed accessories. Refer to the accessory installation instructions included with each accessory.

A.Motormaster® I Control Installation (581A155 and 180 Only)

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. 25 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 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 Motormaster I control must be used in conjunction with the Accessory 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 — Install the Accessory 0° F Low Ambient Kit per instruction supplied with accessory.

NOTE: Dimensions in ( ) are in mm.

Fig. 25 — Wind Baffle Details

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