Carrier JK034-074, 50FK, 48FK specifications Ð Space Temperature Sensor Averaging

				RED	RED
				BLK	BLK
SIZES 034-048
TB3	RED			RED	RED
12
					BLK
15	BLK			BLK
TO ACCESSORY SPACE
TEMPERATURE RESET
CONTROL BOARD
SIZES 054-104
TB4
12
15		SENSOR 1		SENSOR 2	SENSOR 3
		SPACE TEMPERATURE RESET Ð 4 SENSOR AVERAGING APPLICATION
SIZES 034-048
TB3	RED			RED	RED
12
	BLK			BLK	BLK
15
TO ACCESSORY SPACE
TEMPERATURE RESET
CONTROL BOARD				SENSOR 1	SENSOR 2
SIZES 054-104			BLK	RED
TB4
12				RED	RED
15
				BLK	BLK
			BLK	SENSOR 4	SENSOR 5
NOTE: Sensor part number is HH79NZ014.				RED
				RED	RED
				BLK	BLK
				SENSOR 7	SENSOR 8

SPACE TEMPERATURE RESET Ð 9 SENSOR AVERAGING APPLICATION

Fig. 26 Ð Space Temperature Sensor Averaging

SENSOR 4

SENSOR 3

SENSOR 6

SENSOR 9

Demand Limit Ð The demand limit function provides a means to limit the cooling capacity of the VAV unit using an external discrete switch function. When enabled by the closure of the external switch, the control will limit the avail- able compressor staging capacity according to user set points established at demand limit potentiometer(s).

The unit controls support two types of demand limit: single- step and 2-step control.

SINGLE-STEP DEMAND LIMIT Ð This function will limit the total compressor staging based on the ratio of the set point potentiometer's wiper arm position to the full scale resis- tance of the potentiometer. The exact percentage of capacity reduction differs depending on the number of capacity steps.

A ®eld-supplied potentiometer and control switch are re- quired for this function. See installation section for speci- ®cation on potentiometer and ®eld wiring.

TWO-STEP DEMAND LIMIT Ð Two-step demand limit is provided with the installation of the accessory Demand Limit

Control Module kit plus installation of 2 ®eld-supplied con- trol switches (SPST-NO each). This accessory control pro- vides for a ®rst step reduction of 50% to 100% of the maxi- mum compressor staging; the second step provides for reduction between 0% and 49%. The exact percentage of capacity re- duction differs depending on the number of capacity steps.

When demand limit is active, the LED display will show

code 22 .

INSTALLATION

Single-Step Demand Limit Ð A 3-wire 5 to 20 K-ohm po- tentiometer must be ®eld-supplied and installed. A single- pole normally open switch is also required (®eld-supplied and -installed). Locate the potentiometer (designated P4) and the switch in a suitable location (external from the unit or in the unit control box).

18