Greenheck IG Installation, Operation And Maintenance Manual page 32

Start-Up - Economizer (optional)
To prevent premature heat exchanger failure, do not
locate units where chlorinated, halogenated, or acid
vapors are present.
Units with an economizer are designed for either
0-30% outside air (HV-1), 31-75% outside air
(HV-2) or 100% return air (HV-3). Refer to the CAPS
submittal for the unit's ventilation type.
HV-1 and HV-2 use economizer controls (EC) or
(MB).
Economizer control may use outside air temperature
reference (EC-1), outside enthalpy reference
(EC-2), differential temperature reference (EC-3) or
differential temperature reference (EC-4).
Economizer control may use a potentiometer
(MB-1), 2-10 VDC signal (MB-2), 4-20mA signal
(MB-3) or a manual quadrant (MB-4).
1. Verify Sensor Installation
All economizer options (EC) require an outdoor air
temperature or enthalpy sensor to be field-installed
inside of the weatherhood and field-wired to terminals
SO+ and SO- on the economizer.
Economizer options EC-3 and EC-4 require an outdoor
air temperature or enthalpy sensor to be field-installed
in the return air duct and field-wired to terminals SR+
and SR- on the economizer.
Verify that all economizer sensors needed for your
application are properly installed and wired.
2. Set Minimum Outside Air
Set the minimum outside air position. HV-1 is
designed for 0-30% outside air and HV-2 is designed
for 31-75% outside air.
All economizer options, EC-1, EC-2, EC-3 and
EC-4 and option MB-1 use a potentiometer to
set the minimum outside air damper position.
The potentiometer is located on the economizer
for options EC-1, EC-2, EC-3 and EC-4. The
potentiometer may be factory-mounted in the unit
control center or field-mounted in the space for option
MB-1.
MB-2 and MB-3 use an external signal from a building
management system to position the dampers.
MB-4 uses a manual quadrant located on the inlet
damper to position the dampers.
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Model IG / IGX Make-Up Air
NOTE
NOTE
NOTE
NOTE
NOTE
IMPORTANT
The outside air volume must be measured and
compared to the total air volume when setting
the minimum outside air. The minimum outside air
should never be set based on the inlet damper or
potentiometer position.
3. Set the Enthalpy Changeover Set
Point (optional)
If using an economizer, the enthalpy changeover
setting must be set. If differential temperature or
differential enthalpy control is used, set the enthalpy
changeover set point to D. If outside air temperature
or enthalpy reference is used, set the enthalpy
changeover set point to the desired setting from the
following table.
Enthalpy Changeover Setting
Setting
A
B
C
D
*Temperature at 50% relative humidity, see the
Honeywell W7212 Economizer instructions for set
points at other humidities
For options EC-3 and EC-4 the enthalpy changeover set
point is the temperature at which the economizer will
send the dampers to the minimum outside air position.
4. Program Optional Room Stat
Program the optional room stat. Separate detailed
instructions for programming the room stat ship with
the optional room stat.
Changeover
Temperature* (°F)
73
70
67
63
NOTE
®