Carrier 50EJQ Installation, Start-Up And Service Instructions Manual page 22

The default offset set points for modulating power ex-
haust are shown in Table 8.
Table 8 — Power Exhaust Default Set Points
STAGE OFF- DIFFER-
SET ENTIAL VOLTAGE
1 50% 3%
2 55% 3%
3 60% 3%
4 64% 3%
The differential set point is the difference between the
turn off point and the turn on point for each module. It also
is calibrated in terms of percent of input signal, and has a
range of 1% to 7%. The differential potentiometer is cali-
brated in 1% increments, and is factory set at approximately
3%. It is recommended to leave the set point at 3%, to mini-
mize cycling of the fans.
The offset and differential potentiometers have been
factory set for atmospheric pressure. Do not change these
settings until there is some experience with the building. In
most cases the factory settings will be satisfactory. How-
ever, if the building pressure is not being maintained as
desired, then some minor adjusting on a trial and error basis
can be made.
Direct Digital Controls DIP Switch Configura-
tion —
The Direct Digital Control (DDC) board must be
SETTING 1 2
CCN or Sensors
OPEN —
Used
CLOSED CV Thermostat
LEGEND
CCN — Carrier Comfort Network
CV — Constant Volume
UNIT 1
50EJQ,EWQ Closed
OFF
OFF ON STATIC
VOLTAGE PRESSURE
(in. wg)
6.0 6.3 0.00
6.5 6.8 0.06
7.0 7.3 0.12
7.4 7.7 0.18
Table 9 — DIP Switch Configuration
3
Expansion Field Test
Board ON
Base Control Field Test
Board Only OFF
Table 10 — DIP Switch Factory Settings
2 3
Closed Closed
configured for each application. The DDC board is config-
ured through the DIP switches located on the board. There
are 8 DIP switches which configure 8 different applications
of the DDC. See Table 9. DIP switch 1 is on the left of the
block. DIP switch 8 is on the right of the block. To open a
DIP switch, push the switch toward the side marked ''OPEN''
on the rocker switch with a suitable tool (small-blade screw-
driver). To close a DIP switch, push the switch away from
the side marked OPEN on the rocker switch. Factory set-
tings are shown in Table 10.
The DIP switch configurations of the unit control soft-
ware are as follows:
• Set DIP switch 1 to closed to configure the unit to operate
as a CV (constant volume) unit
• DIP switch 2 configures the unit to use a space sensor or
a thermostat
• DIP switch 3 configures the DDC for use with an elec-
tronic expansion board
• DIP switch 4 is used to field test the unit
• DIP switch 5 is used to specify the type of power exhaust
• DIP switch 6 configures the Time Guard override and,
when used with the field test function, sets the minimum
damper position
• Set DIP switch 7 to closed to configure the unit indoor fan
for use with electric heat
• Set DIP switch 8 to open to configure the unit for heat
pump operation
4 5
Time Guard Override
Modulated
IN CONJUNCTION
Power
WITH FIELD TEST
Exhaust
— Set Minimum
Damper Position
Constant
Volume Time Guard Override
Power
Exhaust
NOTES:
1. The OPEN side of the DIP switch is marked ''OPEN.'' When the
rocker switch is on the ''OPEN'' side of the switch, the switch is
OPEN.
2. DIP switch no. 7 is used for indoor fan control during heat opera-
tion. It should be set to closed.
3. When the unit is field-tested (DIP switch 4 to OPEN), the function
of DIP switch 6 changes and it is used to set the minimum damper
position.
4 5
Closed Closed
22
6 7
ON
Gas Heat
Electric Heat
OFF
6 7
Closed Closed
8
Heat Pump
Operation
Air Conditioner
Operation
8
Open