Supply-Air Sensor Placement; Changeover Set Points; Default Potentiometer Settings; Ventilation Air (Minimum Position Set Up) - Carrier 48HJD005-007 Installation, Start-Up And Service Instructions Manual

SUPPLY AIR
TEMPERATURE
SENSOR
MOUNTING
LOCATION
SUPPLY AIR
TEMPERATURE
SENSOR
Fig. 34 — Supply-Air Sensor Placement
CO Control Setup — If a CO
2
ceed to the next section. If a CO
the following:
1. Determine the value at which you want the minimum po-
sition 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
2
desired set point. See Fig. 35.
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
temperature is below this value. See Fig. 35.
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. 35. When the OAT is above this
set point, the damper is limited to minimum position setting.
Table 3 — Changeover Set Points
SETTINGS
Dry Bulb (°F)
Single Enthalpy* (Btu/lb)
Differential Temperature* (°F, Not Adjustable)
Differential Enthalpy* (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
CO SP (PPM)
2
MECH CLG LOCKOUT
ECON SP
MIN POS (%)
sensor is not being used, pro-
2
sensor is being used, perform
2
A B C D
73 69 66 63
27 25 24 22
2 2 2 2
1 1 1 1
DEFAULT SETTING
1,000
47°
D
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 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. 35.
3. Replace the filter access panel. See Fig. 24. 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 =
b. Divide total CFM by percentage outdoor air, this
gives outdoor air volume in CFM.
5. Turn on base unit power.
NOTE: The EconoMi$er begins operation three minutes after
power up.
Personal Injury Hazard. Avoid possible injury by keep-
ing fingers away from damper blades.
6. See Fig. 36 for barometric relief damper characteristics.
Fig. 35 — EconoMi$er Control Adjustment
Potentiometers (Factory Settings)
0.5
0.4
0.3
0.2
0.1
0
0 400
FLOW (CUBIC FEET/MINUTE)
Fig. 36 — Barometric Relief Capacity
18
Mixture Temp –
Return Air Temp
Outdoor Temp –
Return Air Temp
800 1200 1600 2000 2400