Carrier 50TFF008-014 - Changeover Set Points; Default Potentiometer Settings; Mechanical Cooling Lockout; Dry Bulb Changeover Set up

19
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. 40.
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. 40. 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 Settin
g
s
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. 40.
3. Replace the filter access panel. See Fig. 30. 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$er begins operation 15 minutes
after power up.
6. See Fig. 41 for enthalpy changeover set point.
7. See Fig. 42 for barometric relief damper characteristics.
SETTINGS A B C D
Dry Bulb (°F)
73 69 66 63
Single Enthalpy* (Btu/lb)
27 25 24 22
Differential Temperature*
(°F, Not Adjustable)
2222
Differential Enthalpy*
(Btu/lb, Not Adjustable)
1111
POTENTIOMETER DEFAULT SETTING
CO
2
SP (PPM)
1,000
MECH CLG LOCKOUT
47°
ECON SP
D
MIN POS (%)
20
% Outdoor air =
Mixture Temp – Return Air Temp
Outdoor Temp – Return Air Temp
Personal Injury Hazard. Avoid possible injury by keep-
ing fingers away from damper blades.
Fig. 41 — Enthalpy Settings for
EconoMi$er Economizer
CONTROL
CURVE
CONTROL POINT
F (C) APPROX
AT 50% RH
A 73 [23]
B 70 [21]
C 57 [19]
D 53 [17]
0
200
400
600 800 1000
1200
1400 1600
FLOW (CUBIC FEET/MINUTE)
0.5
0.4
0.3
0.2
0.1
0
STATIC PRESSURE (IN. WG)
Fig. 42 — Barometric Relief Capacity
Fig. 40 — EconoMi$er Control Adjustment
Potentiometers (Factory Settings)