Bryant 548F User Manual download pdf (Page 19)

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10. Remove the indoor fan motor access panel. See

Fig. 29.

11. Mount the supply air temperature sensor to the lower

left portion of the indoor blower housing with the two

(2) screws provided (see Fig. 30). Connect the violet

and pink wires to the corresponding connections on

the supply air temperature sensor. Replace the indoor

fan motor access panel.

Control Set Up

If a CO

sensor is not being used, proceed to the next section.

If a CO

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 CO

SP (PPM) potentiometer and adjust

to the desired set point. See Fig. 31.

Mechanical Cooling Lockout

Determine the outdoor-air temperature at which you want

the mechanical cooling (compressors) to be disabled. Locate

the mechanical cooling lockout (MECH CLG LOCKOUT)

potentiometer. To disable this feature, turn the potentiome-

ter counterclockwise (CCW) to the OFF position. Otherwise,

set the value between 10 and 60 F. Mechanical cooling will

not operate when the outdoor-air temperature is below this

value. See Fig. 31.

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 potenti-

ometer and set the dry bulb changeover set point. See

Fig. 31. When the OAT is above this set point, the damper is

limited to minimum position setting.

Table 3 — Changeover Set Points

*Field-installed accessory.

If a potentiometer fails, its setting will default to the values

in Table 4.

Table 4 — Default Potentiometer Settings

Ventilation Air (Minimum Position Set Up)

If ventilation air is not required, proceed to Step 5. If ventila-

tion 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) 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. 31.

3. Replace the filter access panel. See Fig. 20. 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

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 minutes after

power up.

6. See Fig. 32 for barometric relief damper characteristics.

SETTINGS ABCD

Dry Bulb (°F)

73 69 66 63

Single Enthalpy* (Btu/lb)

27 25 24 22

Differential Temperature*

(°F, Not Adjustable)

2222

Differential Enthalpy*

(Btu/lb, Not Adjustable)

1111

POTENTIOMETER DEFAULT SETTING

SP (PPM)

1,000

MECH CLG LOCKOUT

47°

ECON SP

MIN POS (%)

% Outdoor air =

Mixture Temp – Return Air Temp

Outdoor Temp – Return Air Temp

WARNING: Personal Injury Hazard. Avoid pos-

sible injury by keeping fingers away from damper

blades.

CONTROL BOX

ACCESS PANEL

INDOOR FAN MOTOR

ACCESS PANEL

SUPPLY AIR

TEMPERATURE

SENSOR

MOUNTING

LOCATION

SUPPLY AIR

TEMPERATURE

SENSOR

Fig. 29 — Typical Access Panel Locations

(Standard Efficiency Unit Shown)

Fig. 30 — Supply Air Sensor Placement

Fig. 31 — EconoMi$er Control Adjustment

Potentiometers (Factory Settings)

1 2 ... 14 15 16 17 18 19 20 21 22 23 24 ... 47 48

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Bryant 548F User Manual Page 19

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