York YPAL 061, YPAL 050, YPAL 051, YPAL 060 Furnace Status Input, CO2 Sensor Output, PPM CO2 Output

Service

CO2 Sensor

Two CO2 sensors are used in conjunction with the “DEMAND VENTILATION” option. In “DEMAND VENTILATION” the Unit Control monitors the CO2 level of the outdoor air and the CO2 level in the conditioned space and varies the amount of ventilation air based on the relationship between these two values. Table 8-7 gives the volts DC output for a given CO2 level.

TABLE 8-7 – CO2 SENSOR OUTPUT

PPM CO2	OUTPUT	PPM CO2	OUTPUT
	VOLTAGE		VOLTAGE
	VDC		VDC
80	0.20	1120	2.80
160	0.40	1200	3.00
240	0.60	1280	3.20
320	0.80	1360	3.40
400	1.00	1440	3.60
480	1.20	1520	3.80
560	1.40	1600	4.00
640	1.60	1680	4.20
720	1.80	1760	4.40
800	2.00	1840	4.60
880	2.20	1920	4.80
960	2.40	2000	5.00
1040	2.60

FORM 100.50-NOM6 (1207)

Furnace Status Input

The Unit Controller monitors the operation of the Staged and Modulating Gas Heat sections and displays the status through the STATUS screen of the User Interface. The operation of each of the gas heat sections is monitored by a multiplexer installed in the gas heat section. When a gas heat section is energized, it sends a 24-volt signal to the multiplexer. The multiplexer takes the five “ON”/”OFF” inputs and converts them into a 0 to 5 volt DC signal that is sent to the Unit Controller. The Unit Controller then decodes this analog input and displays the furnace section status. Tables 8-9 and 8-10 show the relationship between the DC voltage and the furnace operation status.

156 JOHNSON CONTROLS