SUPPLY AIR

TEMPERATURE

SENSOR

MOUNTING

LOCATION

SUPPLY AIR

TEMPERATURE

SENSOR

Fig. 37 — Supply-Air Sensor Placement

CO2 Control Set Up — If a CO2 sensor is not being used, proceed to the next section. If a CO2 sensor is being used, per- form 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. 38.

Mechanical Cooling Lockout — Determine the outdoor-air temperature at which you want the mechanical cooling (com- pressors) to be disabled. Locate the mechanical cooling lock- out (MECH CLG LOCKOUT) potentiometer. To disable this feature, 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. 38.

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. 38. When the OAT is above this set point, the damper is limited to minimum position setting.

Table 3 — Changeover 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 Settings

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 required, 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 connection board.

2.Locate the minimum position (MIN POS) potentiometer. Turn the potentiometer full CCW to fully close the out- door air dampers. Turn the potentiometer gradually clockwise (CW) to the desired position. See Fig. 38.

3.Replace the filter access panel. See Fig. 26. Ensure the fil- ter 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. 39 for barometric relief damper characteristics.

Fig. 38 — 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. 39 — Barometric Relief Capacity

 

 

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Carrier 48TJE, TJF004, TJF005-007, 48TJD specifications Changeover Set Points, Default Potentiometer Settings