User`s manual

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20
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M e c h anica l Coo lin g L o c ko ut
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. 43.
Dry Bulb Changeover Set Up
Determine the dry bulb changeover set point from Table 4.
The settings are A, B, C and D. Locate the ECON SP potenti-
ometer and set the dry bulb changeover set point. See
Fig. 43. When the OAT is above this set point, the damper is
limited to minimum position setting.
Tabl e 4 — Changeover Set Points
*Field-installed accessory.
If a potentiometer fails, its setting will default to the values
in Table 5.
Table 5 — 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. 43.
3. Replace the filter access panel. See Fig. 32. 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$er begins operation three minutes after
power up.
See Fig. 44 for barometric relief damper characteristics.
PRE-START-UP
SETTINGS ABCD
Dry Bulb (°F)
73 69 66 63
Single Enthalpy* (Btu/lb)
27 25 24 22
Differential Temperature*
(°F, Not Adjustable)
2222
Differential Enthalpy*
(Btu/lb, Not Adjustable)
1111
POTENTIOMETER DEFAULT SETTING
CO
2
SP (PPM)
1,000
MECH CLG LOCKOUT
47°
ECON SP
D
MIN POS (%)
20
% Outdoor air =
Mixture Temp –
Return Air Temp
Outdoor Temp –
Return Air Temp
WARNING:
Personal Injury Hazard.
Avoid possible
injury by keeping fingers away from damper blades.
WARNING: Failure to observe the following warn-
ings could result in serious personal injury:
1. Follow recognized safety practices and wear
protective goggles when checking or servicing
refrigerant system.
2. Do not operate compressor or provide any elec-
tric power to unit unless compressor terminal
cover is in place and secured.
3. Do not remove compressor terminal cover until
all electrical sources have been disconnected
and lockout tags installed.
4. Relieve all pressure from system before touch-
ing or disturbing anything inside terminal box
if refrigerant leak is suspected around compres-
sor terminals.
5. Never attempt to repair soldered connection
while refrigerant system is under pressure.
6. Do not use torch to remove any component. Sys-
tem contains oil and refrigerant under pres-
sure. To remove a component, wear protective
goggles and proceed as follows:
a. Shut off gas supply and then electrical power
to unit.
b. Relieve all pressure from system.
c. Cut component-connecting tubing with tub-
ing cutter and remove component from unit.
d. Carefully unsweat remaining tubing stubs
when necessary. Oil can ignite when exposed
to torch flame.
0
400
800
1200
1600
2000
2400
FLOW (CUBIC FEET/MINUTE)
0.5
0.4
0.3
0.2
0.1
0
STATIC PRESSURE (IN.WG)
Fig. 43 — EconoMi$er Control Adjustment
Potentiometers (Factory Settings)
Fig. 44 — Barometric Relief Capacity