Carrier 48/50AJ Heating Configuration, Occupied Heating Enable OC.EN This configuration

Table 65 — Heating Configuration

ITEM	EXPANSION	RANGE		UNITS	CCN POINT	DEFAULT
HEAT	HEATING CONFIGURATION
HT.CF	Heating Control Type	0	- 3		HEATTYPE	0*
HT.SP	Heating Supply Air Setpt	80 - 120		dF	SASPHEAT	85
OC.EN	Occupied Heating Enabled	Yes/No			HTOCCENA	No
LAT.M	MBB Sensor Heat Relocate	Yes/No			HTLATMON	No
G.FOD	Fan Off Delay, Gas Heat	45 - 600		sec	GAS_FOD	45
E.FOD	Fan Off Delay, Elec Heat	10 - 600		sec	ELEC_FOD	30
SG.CF	STAGED GAS CONFIGS
HT.ST	Staged Gas Heat Type	0	- 4		HTSTGTYP	0*
CAP.M	Max Cap Change per Cycle	5	- 45		HTCAPMAX	45*
M.R.DB	S.Gas DB min.dF/PID Rate	0	- 5		HT_MR_DB	0.5
S.G.DB	St.Gas Temp. Dead Band	0	- 5	^F	HT_SG_DB	2
RISE	Heat Rise dF/sec Clamp	0.05 - 0.2			HTSGRISE	0.06
LAT.L	LAT Limit Config	0	- 20	^F	HTLATLIM	10
LIM.M	Limit Switch Monitoring?	Yes/No			HTLIMMON	Yes
SW.H.T	Limit Switch High Temp	110 - 180		dF	HT_LIMHI	170*
SW.L.T	Limit Switch Low Temp	100 - 170		dF	HT_LIMLO	160*
HT.P	Heat Control Prop. Gain	0	- 1.5		HT_PGAIN	1
HT.D	Heat Control Derv. Gain	0	- 1.5		HT_DGAIN	1
HT.TM	Heat PID Rate Config	60 - 300		sec	HTSGPIDR	90

*Some defaults are model number dependent.

Occupied Heating Enable (OC.EN) — This configuration

only applies when the unit’s control type (Configuration →UNIT→C.TYP) is configured for 1 (VAV-RAT) or 2 (VAV- SPT). If the user wants to have the capability of performing heating throughout the entire occupied period, then this config- uration needs to be set to “YES”. Most installations do not re- quire this capability, and if heating is installed, it is used to heat the building in the morning. In this case set OC.EN to “NO”.

NOTE: This unit does not support simultaneous heating and cooling. If significant simultaneous heating and cooling demand is expected, it may be necessary to provide additional heating or cooling equipment and a control system to provide occupants with proper comfort.

MBB Sensor Heat Relocate (LAT.M) — This option allows the user additional performance benefit when under CCN Linkage for the 2-stage electric and gas heating types. As two- stage heating types do not “modulate” to a supply air set point, no leaving air thermistor is required and none is provided. The evaporator discharge thermistor, which is initially installed up- stream of the heater, can be repositioned downstream and the control can expect to sense this heat. While the control does not need this to energize stages of heat, the control can wait for a sufficient temperature rise before announcing a heating mode to a CCN linkage system (ComfortID™).

If the sensor is relocated, the user will now have the capability to view the leaving-air temperature at all times at Temperatures→AIR.T→CTRL→LAT.

NOTE: If the user does not relocate this sensor for the 2-stage electric or gas heating types and is under CCN Linkage, then the control will send a heating mode (if present) uncondition- ally to the linkage coordinator in the CCN zoning system regardless of the leaving-air temperature.

Fan-Off Delay, Gas Heat (G.FOD) — This configuration is the delay in seconds, after a gas heat mode has ended (HT.CF=2,3) that the control will continue to energize the supply fan.

Fan-Off Delay, Elec Heat (E.FOD) — This configuration is the delay in seconds, after an electric heat mode has ended (HT.CF=1) that the control will continue to energize the supply fan.

HEAT MODE SELECTION PROCESS — There are two possible heat modes that the control will call out for heating control: HVAC Mode = LOW HEAT and HVAC Mode = HIGH HEAT. These modes will be called out based on control type (C.TYP).

VAV-RAT (C.TYP = 1) and VAV-SPT (C.TYP = 2) — There is no difference in the selection of a heating mode for either

VAV-RAT or VAV-SPT, except that for VAV-SPT, space tem- perature is used in the unoccupied period to turn on the supply fan for 10 minutes before checking return-air temperature. The actual selection of a heat mode, LOW or HIGH for both control types, will be based upon the controlling return-air temperature.

With sufficient heating demand, there are still conditions that will prevent the unit from selecting a heat mode. First, the unit must be configured for a heat type (Configuration→ HEAT→HT.CF not equal to “NONE”). Second, the unit has a configuration which can enable or disable heating in the occupied period except for a standard morning warmup cycle (Configuration→HEAT→OC.EN). See descriptions above in the Setting Up the System section for more information.

If the unit is allowed to select a heat mode, then the next step is an evaluation of demand versus set point. At this point, the logic is the same as for control types SPT Multi-Stage and SPT-2 Stage, (C.TYP = 5,6) except for the actual temperature compared against set point. See Temperature Driven Heat Mode Evaluation section.

Tstat-Multi-Stage (C.TYP = 3) and Tstat-2 Stage (C.TYP = 4) — There is no difference in the selection of a heat mode be- tween the control types TSTAT 2-stage or TSTAT multi-stage. These selections only refer to how cooling will be handled. With thermostat control the W1 and W2 inputs determine whether the HVAC Mode is LOW or HIGH HEAT.

W1 = ON, W2 = OFF: HVAC MODE = LOW HEAT*

W2 = ON, W2 = ON: HVAC MODE = HIGH HEAT

*If the heating type is either 2-stage electric or 2-stage gas, the unit may promote a low heat mode to a high heat mode.

NOTE: If W2 = ON and W1 is OFF, a “HIGH HEAT” HVAC Mode will be called out but an alert (T422) will be generated. See Alarms and Alerts section on page 93.

SPT Multi-Stage (C.TYP = 5) and SPT 2 Stage (C.TYP = 6)

—There is no difference in the selection of a heat mode between the control types SPT 2-stage or SPT multi-stage. These selections only refer to how cooling will be handled. So, for a valid heating type selected (HT.CF not equal to zero) the unit is free to select a heating mode based on space temperature (SPT).

If the unit is allowed to select a heat mode, then the next step is an evaluation of demand versus set point. At this point, the logic is the same as for control types VAV-RAT and VAV-SPT (C.TYP = 1,2), except for the actual temperature compared against set point. See Temperature Driven Heat Mode Evaluation section on page 52.

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