Carrier Air Conditioner specifications Required Hardware for Additional Unloaders

ADDING ADDITIONAL UNLOADERS — See Table 6 below for required hardware.

Follow accessory instructions for installation. Connect un- loader coil leads to PINK wires in compressor A1/B1 junction box. Configuration items CA.UN and CB.UN in the OPT1 sub-mode of the configuration mode must be changed to match the new number of unloaders. Two unloaders cannot be used with hot gas bypass on a single circuit.

MINUTES LEFT FOR START — This value is displayed only in the network display tables (using Service Tool or ComfortWORKS® software) and represents the amount of time to elapse before the unit will start its initialization routine. This value can be zero without the machine running in many situations. This can include being unoccupied, ENABLE/OFF/ REMOTE CONTACT switch in the OFF position, CCN not allowing unit to start, Demand Limit in effect, no call for cool- ing due to no load, and alarm or alert conditions present. If the machine should be running and none of the above are true, a minimum off time (DELY, see below) may be in effect. The machine should start normally once the time limit has expired.

MINUTES OFF TIME (DELY, Configuration Mode under OPT2) — This user configurable time period is used by the control to determine how long unit operation is delayed after power is applied/restored to the unit. Typically, this time period is configured when multiple machines are located on a single site. For example, this gives the user the ability to prevent all the units from restarting at once after a power failure. A value of zero for this variable does not mean that the unit should be running.

LOADING SEQUENCE — The 30GTN,R and 30GUN,R compressor efficiency is greatest at partial load. Therefore, the following sequence list applies to capacity control.

The next compressor will be started with unloaders ener- gized on both lead compressors.

All valid capacity combinations using unloaders will be used as long as the total capacity is increasing.

LEAD/LAG DETERMINATION (LLCS, Configuration Mode under OPT2) — This is a configurable choice and is factory set to be automatic (for sizes 080-420) or Circuit A leading (for 040-070 sizes). For 040-070 sizes, the value can be changed to Automatic or Circuit B only if an accessory unload- er is added to compressor B1. For 080-420 sizes, the value can be changed to Circuit A or Circuit B leading, as desired. Set at automatic, the control will sum the current number of logged circuit starts and one-quarter of the current operating hours for each circuit. The circuit with the lowest sum is started first. Changes to which circuit is the lead circuit and which is the lag are also made when total machine capacity is at 100% or when

there is a change in the direction of capacity (increase or de- crease) and each circuit’s capacity is equal.

CAPACITY SEQUENCE DETERMINATION (LOAD, Configuration Mode under OPT2) — This is configurable as equal circuit loading or staged circuit loading with the default set at equal. The control determines the order in which the steps of capacity for each circuit are changed. This control choice does NOT have any impact on machines with only 2 compressors.

CAPACITY CONTROL OVERRIDES — The following overrides will modify the normal operation of the routine.

Deadband Multiplier — The user configurable Deadband Multiplier (Z.GN, Configuration Mode under SLCT) has a default value of 1.0. The range is from 1.0 to 4.0. When set to other than 1.0, this factor is applied to the capacity Load/Un- load Factor. The larger this value is set, the longer the control will delay between adding or removing stages of capacity. Figure 17 shows how compressor starts can be reduced over time if the leaving water temperature is allowed to drift a larger amount above and below the set point. This value should be set in the range of 3.0 to 4.0 for systems with small loop volumes.

First Stage Override — If the current capacity stage is zero, the control will modify the routine with a 1.2 factor on adding the first stage to reduce cycling. This factor is also applied when the control is attempting to remove the last stage of capacity.

Slow Change Override — The control prevents the capacity stages from being changed when the leaving fluid temperature is close to the set point (within an adjustable deadband) and moving towards the set point.

Ramp Loading (CRMP, Configuration Mode under SLCT) — Limits the rate of change of leaving fluid temperature. If the unit is in a Cooling mode and configured for Ramp Loading, the control makes 2 comparisons before deciding to change stages of capacity. The control calculates a temperature differ- ence between the control point and leaving fluid temperature. If the difference is greater than 4° F (2.2° C) and the rate of change (°F or °C per minute) is more than the configured Cool- ing Ramp Loading value (CRMP), the control does not allow any changes to the current stage of capacity.

Low Entering Fluid Temperature Unloading — When the entering fluid temperature is below the control point, the con- trol will attempt to remove 25% of the current stages being used. If exactly 25% cannot be removed, the control removes an amount greater than 25% but no more than necessary. The lowest stage will not be removed.

Table 6 — Required Hardware for Additional Unloaders

UNIT	COMP.	FACTORY	ADDITIONAL	UNLOADER	SOLENOID	CXB ACCESSORY†
30GTN,GTR,GUN,GUR		STANDARD	UNLOADERS	PACKAGE*	COIL
040 (60 Hz)	A1	1	0	N/A	N/A	Not Required
	B1	0	1	06EA-660---138	EF19ZE024
040 (50 Hz)	A1	1	0	N/A	N/A	Not Required
			1		EF19ZE024
045 (60 Hz)	B1	0		06EA-660---138
			2		Not Required	30GT-911---031
045 (50 Hz)	A1	1	1		EF19ZE024	Not Required
			1	06EA-660---138
050-070	B1	0
			2		Not Required	30GT-911---031
080-110**	A1	1	1	06EA-660---138	Not Required	30GT-911---031
130 (60 Hz)	B1	1	1
130 (50 Hz)	A1	1	1	06EA-660---138	EF19ZE024	Not Required
150-210**	B1	1	1
LEGEND				*Requires one per additional unloader.
CBX — Compressor Expansion Board				†2 solenoid coils are included in the CXB Accessory.
				**And associated modular units.

26