Carrier 48TF004-007 Chan geover Set Points, Default Potentiometer Settin gs, Settings

SUPPLY AIR

TEMPERATURE

SENSOR

MOUNTING

LOCATION

SUPPLY AIR

TEMPERATURE

SENSOR

Fig. 36 — Supply-Air Sensor Placement

CO2 Control Setup — If a CO 2 sensor is not being used, pro-

ceed to the next section. If a CO2 sensor is being used, perform the following:

1.Determine the value at which you want the minimum position of the dampers to begin opening to allow a greater amount of outdoor air to enter. The range is 800 to 1,400 ppm.

2.Locate the CO2 SP (PPM) potentiometer and adjust to the desired set point. See Fig. 37.

Mechanical Cooling Lockout — Determine the outdoor-air temperature at which you want the mechanical cooling (com- pressors) to be disabled. Locate the mechanical cooling lockout (MECH CLG LOCKOUT) potentiometer. To disable this fea- ture, turn the potentiometer counterclockwise (CCW) to the OFF position. Otherwise, set the value between 10 and 60 F. Mechanical cooling will not operate when the outdoor air tem- perature is below this value. See Fig. 37.

Dry Bulb Changeover Set Up — Determine the dry bulb changeover set point from Table 3. The settings are A, B, C and D. Locate the ECON SP potentiometer and set the dry bulb changeover set point. See Fig. 37. When the OAT is above this set point, the damper is limited to minimum position setting.

Table 3 — Chan geover Set Points

SETTINGS	A	B	C	D
Dry Bulb (°F)	73	69	66	63
Single Enthalpy* (Btu/lb)	27	25	24	22
Differential Temperature*	2	2	2	2
(°F, Not Adjustable)
Differential Enthalpy*	1	1	1	1
(Btu/lb, Not Adjustable)
*Field-installed accessory.

If a potentiometer fails, its setting will default to the values in Table 4.

Table 4 — Default Potentiometer Settin gs

POTENTIOMETER	DEFAULT SETTING
CO2 SP (PPM)	1,000
MECH CLG LOCKOUT	47°
ECON SP	D
MIN POS (%)	20

Ventilation Air (Minimum Position Set Up) — If ventilation air is not required, proceed to Step 5. If ventilation air is re- quired, perform the following:

1.The indoor fan must be on to set the ventilation air. Either put the thermostat in the continuous fan mode or jumper the R and G terminals at the rooftop unit con- nection board.

2.Locate the minimum position (MIN POS) potentiome- ter. Turn the potentiometer full CCW to fully close the outdoor air dampers. Turn the potentiometer gradually clockwise (CW) to the desired position. See Fig. 37.

3.Replace the filter access panel. See Fig. 26. Ensure the filter access panel slides along the tracks and is securely engaged.

4.Calculate the minimum airflow across the EconoMi$er.

a.Calculate % of outside air using the following formula.

%Outdoor air through EconoMi$er

%Outdoor air = Mixture Temp – Return Air Temp Outdoor Temp – Return Air Temp

b.Divide total CFM by percentage outdoor air, this gives outdoor air volume in CFM.

5.Turn on base unit power.

NOTE: The EconoMi$er begins operation three min- utes after power up.

Personal Injury Hazard. Avoid possible injury by keep- ing fingers away from damper blades.

6. See Fig. 38 for barometric relief damper characteristics.

Fig. 37 — EconoMi$er Control Adjustment Potentiometers (Factory Settings)

WG)	0.5
	0.4
(IN.
PRESSURE	0.3
	0.2
STATIC	0.1
	0
		200	400	600	800	1000	1200	1400	1600
	0
			FLOW (CUBIC FEET/MINUTE)

Fig. 38 — Barometric Relief Capacity

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