Johnson Controls GG8S*MP Adjustment Of Temperature Rise, Adjustment Of Fan Control Settings

356485-UIM-G-1211

MANIFOLD PRESSURE “U” TUBE CONNECTION

	OUTLET
	PRESSURE TAP
GAS VALVE		1/4” TUBING
FLAME			MAINIFOLD
			PIPE
SENSOR
			3.5 IN
			WATER
			COLUMN
GAS			GAS
		U-TUBE	PRESSURE
BURNERS
		MANOMETER	SHOWN

FIGURE 26: Reading Gas Pressure

ADJUSTMENT OF TEMPERATURE RISE

DANGER

The temperature rise, or temperature difference between the return air and the supply (heated) air from the furnace, must be within the range shown on the furnace rating plate and within the application limitations shown in SECTION 6.

The supply air temperature cannot exceed the “Maximum Supply Air Temperature” specified in these instructions and on the fur- nace rating plate. Under NO circumstances can the furnace be allowed to operate above the Maximum Supply Air Temperature. Operating the furnace above the Maximum Supply Air Temperature will cause premature heat exchanger failure, high levels of Carbon Monoxide, a fire hazard, personal injury, property damage, and/or death.

After about 5 minutes of operation, determine the furnace temperature rise. Take readings of both the return air and the heated air in the ducts, about six feet (1.83 m) from the furnace where they will not be affected by radiant heat. Increase the blower speed to decrease the temperature rise; decrease the blower speed to increase the rise.

All direct-drive blowers have multi-speed motors. The blower motor speed taps are located on the furnace control board in the blower com- partment. Refer to Figure 27, and the unit-wiring label to change the blower speed. To use the same speed tap for heating and cooling, the heat terminal and cool terminal must be connected using a jumper wire and connected to the desired motor lead. Place all unused motor leads on park terminals. Two park terminals are provided.

Do not energize more than one motor speed at a time or damage to the motor will result.

ADJUSTMENT OF FAN CONTROL SETTINGS

This furnace is equipped with a time-on/time-off heating fan control. The fan on delay is fixed at 30 seconds. The fan off delay has 4 settings (60, 90, 120 and 180 seconds). The fan off delay is factory set to 120 sec- onds. The fan-off setting must be long enough to adequately cool the furnace, but not so long that cold air is blown into the heated space. The fan-off timing may be adjusted by positioning the jumper on two of the four pins as shown in Figure 27.

Blower Off Delay Timer (In seconds)

TWIN
			PARK	PARK
180	120	90	60	HI COOL
	DELAY	BLOWER OFF
Y/Y2				HEAT
W				EAC-H
R
G				L1
C				XFMR
				NEUTRALS
			HUM

FIGURE 27: Furnace Control Board

Johnson Controls Unitary Products 23