White Rodgers 21D28-6 Installation Instructions

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FAILURE TO READ AND FOLLOW ALL INSTRUCTIONS CAREFULLY BEFORE INSTALLING OR OPERATING THIS CONTROL COULD CAUSE PERSONAL INJURY AND/OR PROPERTY DAMAGE.

DESCRIPTION

This Evaporative Cooler Control has a rain-proof enclosure and can be used with either 120 VAC or 240 VAC systems. It was designed for use with White-Rodgers 1F51-619, 1F51W-619, or 1D51W-632 Thermostats to provide automatic temperature and ventilation control and remote fan speed selection of an evaporative cooler with 2-speed fan. The pump relay is automatically operated to allow wetting of cooler pads before starting fan.

8A18Z-2

Evaporative Cooler Control

INSTALLATION INSTRUCTIONS

PRECAUTIONS

If in doubt about whether your wiring is millivolt, line, or low voltage, have it inspected by a qualified heating and air conditioning contractor, electrician, or someone familiar with basic electricity and wiring.

Do not exceed the specification ratings. All wiring must conform to local and national electrical

codes and ordinances. This control is a precision instrument, and should be

handled carefully. Rough handling or distorting components could cause the control to malfunction.

CAUTION

To prevent electrical shock and/or equipment damage, disconnect electric power to system, at main fuse or circuit breaker box, until installation is complete.

WARNING

Do not use on circuits exceeding specified voltage. Higher voltage will damage control and could cause shock or fire hazard.

www.white-rodgers.com

PART NO. 37-5918C

Replaces 37-5918B

0720

SPECIFICATIONS

Case

Panel

Cover

Flat washers

Bolts

Mounting holes

for four bolts and washers

Panel mounting

screws

Cover screw

Figure 2. Installing control

Electrical Ratings:

Input Voltage: 120 or 240 VAC, 60 Hz.

Operating Ambient Temperature Range:

40 to 150°F (5 to 65°C)

Power Consumption:

6 Watts nominal with all three relays energized

Fan Rating:

12 FLA., 72 LRA; 120 VAC 6 FLA., 36 LRA; 240 VAC

Pump Rating:

10 FLA., 60 LRA: 120 VAC 5 FLA., 30 LRA; 240 VAC

The 8A18Z-2 Evaporative Cooler Control consists of three relays and a low voltage transformer with dual voltage primary. The pump relay is automatically operated, which allows the cooler pads to become wet before the fan starts. This will eliminate the fan from blowing dust, warm air, and odor on initial start-up. The fan relay controls operation of the fan without the pump when the thermostat subbase is in the vent position, and controls operation of both fan and pump when the thermostat subbase is in the cool position.

Combined Total Connected Load:

16 FLA., 120 VAC 8 FLA., 240 VAC

Mounting:

Four 9¦32” Dia. holes (2 1¦2” x 5” center line to center line)

Dimensions:

6” wide x 8” high x 3” deep

Line

connections

120V

240V

Fan timer

relay

Pump

connections

Fan

connections

Figure 1. Panel assembly

8A18Z-2

Low voltage transformer

Pump relay

Low voltage thermostat connections

Fan speed relay

INSTALLATION

1. Remove cover screw. To remove cover, pull cover outward at the top, then lift cover off the locating tabs at the bottom of the case.

2. Remove panel assembly from case and discard packing material.

NOTE

Place panel assembly in a safe location to prevent damage to the panel while installing the case.

3. Determine which knockouts will be used for electrical conduits, then remove electrical knockouts from case before mounting.

If the larger knockout is to be removed, remove the smaller knockout before removing the larger one.

4. To remove the knockouts, place a screwdriver on the knockout at the location indicated by the arrow (see fig. 3). Tap the screwdriver to pop the knockout out of the case. If the knockout is not completely removed, carefully use pliers to twist the knockout until it comes out.

NOTE

Figure 3. Electrical knockouts

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