Carrier 48EJ, EW, EK, EY024-048 installation instructions User Dened Set Points

Table 18 Ð User De®ned Set Points

	SET POINT	FORMAT	DESCRIPTION	LIMITS	DEFAULT
	NAME
	OHSP	xx.xF	Occupied Heat Set Point	55 to 80 F	68 F
	OCSP	xx.xF	Occupied Cool Set Point	55 to 80 F	78 F
	UHSP	xx.xF	Unoccupied Heat Set Point	40 to 80 F	55 F
	UCSP	xx.xF	Unoccupied Cool Set Point	75 to 95 F	90 F
	SASP	xx.xF	Supply Air Set Point	45 to 70 F	55 F
	OATL	xx.xF	Hi OAT Lockout Temperature	55 to 75 F	65 F
	NTLO	xx.xF	Unoccupied OAT Lockout Temperature	40 to 70 F	50 F
	RTIO	xx.x	Reset Ratio	0 to 10	3
	LIMT	xx.xF	Reset Limit	0 to 20° F	10%
	MDP	xxx%	Minimum Damper Position	0 to 100%	20%
	LOWMDP	xxx%	Low Temperature Minimum	0 to 100%	100%
			Damper Position Override
	IAQS	xxxx	IAQ Set Point	1 to 5000 PPM	650 PPM
	UHDB	xx.xF	Unoccupied Heating Deadband	0 to 10° F	1° F
	UCDB	xx.xF	Unoccupied Cooling Deadband	0 to 10° F	1° F
	LTMP	xxx%	Low Temp. Min. Position	0 to 100%	10%
	HTMP	xxx%	High Temp. Min. Position	0 to 100%	35%
	PES1	xxx%	CV Power Exhaust Stage 1 Point	0 to 100%	25%
	PES2	xxx%	CV Power Exhaust Stage 2 Point	0 to 100%	75%
	LEGEND
CV	Ð Constant Volume
IAQ	Ð Indoor Air Quality

OAT Ð Outdoor-Air Temperature

If thermostats are used to deenergize the G input, the con- trol board will turn off indoor fan without any delay and close economizer dampers.

When cooling, G must be energized before cooling can operate. The control board determines if outdoor conditions are suitable for economizer cooling using the standard out- door air thermistor. For economizer to function for free cool- ing, the enthalpy must be low, the outdoor air must equal to or less than the High Outdoor Air Temperature Lockout (de- fault is 65 F), the SAT (supply-air temperature) thermistor is NOT in alarm, and outdoor air reading is available. When these conditions are satis®ed, the control board will use econo- mizer as the ®rst stage of cooling.

When Y1 input is energized, the economizer will be modu- lated to maintain SAT at the de®ned set point. The default is 55 F. When SAT is above the set point, the economizer will be 100% open. When SAT is below the set point, the econo- mizer will modulate between minimum and 100% open po- sition. When Y2 is energized, the control will turn on com- pressor no. 1 and continue to modulate economizer as described above. If the Y2 remains energized and the SAT reading re- mains above the set point for 15 minutes, compressor no. 2 will turn on. If Y2 is deenergized at any time, only the last stage of compression that was energized will be turned off. If outdoor conditions are not suitable for economizer cool- ing, the economizer will go to minimum position and cycle compressor no. 1 and 2 based on demand from Y1 and Y2 respectively. The compressors will be locked out when the SAT temperature is too low (less than 40 F for compressor no. 1 and less than 45 F for compressor no. 2.) After a com- pressor is locked out, it can restart after normal time guard period.

The Time Guard function maintains a minimum off time of 5 minutes, a minimum ON time of 10 seconds, and a minimum delay before starting the second compressor of 10 seconds.

When heating, the heat stages respond to the demand from W1 and W2 of the thermostat input. Heating and cooling will be mutually locked out on demand on a ®rst call basis. The heating and the cooling functions cannot be operating simultaneously.

COOLING, VARIABLE VOLUME UNITS Ð On power up, the control module will activate the initialization software

of the control board. The initialization software then reads DIP switch no. 1 position to determine CV or VAV opera- tion. Initialization clears all alarms and alerts, re-maps the input/output database for VAV operation, sets maximum heat stages to 1 and sets maximum cool stages to 6. The control reads DIP switch no. 3 and if open, then it sets the internal ¯ag for expansion mode operation.

The control board will determine if an interface (linkage) is active and if the unit will operate in a Digital Air Volume (DAV) mode. In a DAV system, the room terminals are equipped with microprocessor controls that give commands to the base unit module. If an interface is active, the control will replace local comfort set points, space and return air temperatures and occupancy status with the linkage data supplied.

The control board will determine occupancy status from Time Schedules (if programmed), Remote Occupied/ Unoccupied input, global occupancy, or DAV. If tempera- ture compensated start is active, the unit will be controlled as in the Occupied mode.

NOTE: The temperature compensated start is a period of time calculated to bring the unit on while unoccupied to reach the occupied set point when occupancy occurs.

The control board will set the appropriate operating mode and fan control. The control board will turn VFD on if Oc- cupied mode is evident.

For units equipped with a start/stop switch only (no space temperature sensor), if unoccupied and valid return-air tem- perature reading is available (either from a sensor or DAV), the control will monitor return-air temperature against Un- occupied Heat and Cool set points.

For units with a start-stop switch and a space temperature sensor, the control board will start the VFD whenever SPT is outside of the set points (Unoccupied Heat or Unoccupied Cool). The VFD may also be started by nighttime thermostat via remote Occupied/Unoccupied input or by a temperature compensated start algorithm. When VFD is running in a nor- mal mode, the control will start heating or cooling as re- quired to maintain supply-air temperature at the supply air set point plus the reset (when enabled). The reset value is determined by SAT (supply-air temperature) reset and/or space temperature reset algorithms. The space temperature reset is only available when enabled through software.

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