White Rodgers TYPE 151 installation instructions Wiring, Setting the Dial

INSTALLATION CONT.

IMPORTANT

When control is located where ambient temperature is below freezing, choose a control location far enough away from doors and windows so that moisture will not condense on control.

If the thermostat is used with unit coolers, the following suggestions may help. (See Fig. 2).

1.Position “A” is good if it is sufficiently close to the unit cooler so that the return air to the cooler flows over the thermostat.

2.Position “B” is good if it is not necessary to make frequent adjustments of the dial setting.

3.Position “C” is all right if it is sufficiently far from the cooler that air flowing over the thermostat is not much above the average room temperature.

4.In general, position “D” is not advisable because the post may prevent air from circulating over the thermo- stat.

WIRING

	CEILING
	POST	PARTITION
		WALL OR POST
	UNIT	DIRECTLY
		BEHIND UNIT
		B
D	C	A
	RETURN AIR

FLOOR

Figure 2

All wiring should be done in accordance with local and national electrical codes and ordinances.

If the manufacturer of the cooling equipment has supplied a wiring diagram, follow the manufacturer’s recommenda- tions. The following diagrams show the general use of these controls.

TEMPERATURE

CONTROL

TO LINE SWITCH	HOT
AND POWER SUPPLY	GND

HIGH SIDE

PRESSURE CONTROL

(IF USED)

Circuit showing temperature control con- trolling compressor directly.

TO LINE SWITCH

AND POWER SUPPLYTEMPERATURE CONTROL

Circuit showing temperature control to open and close refrigerant valve. Suction pressure control starts and stops compressor through motor starter.

MOTOR

STARTER

HIGH SIDE	SUCTION	SOLENOID
		REFRIGERANT
PRESSURE	PRESSURE
CONTROL	CONTROL	VALVE

SETTING THE DIAL

To set the dial, simply move it so that the indicating line on the case points to the temperature at which the contacts are to open as the temperature drops.

INDICATING

LINE

70

60

80

2