Demand Control Ventilation - Lennox Core Unit Controller Setup Manual

Damper Travel: % of Maximum Open
Measure A7 Current in Series
Temp. °F (°C) Size Resistor
30 (-1) 34,566
40 ( 4) 26,106
c. Check all connections and wiring between RT17 and the
CORE Unit Controller, and between RT16 and the CORE
Unit Controller.
STEP 6. GLObAL MODULATING (GLO) MODE OF
OPERATION
In the GLO (modulating) mode, dampers modulate open for
free cooling when the global input is energized; dampers
will try to modulate discharge air temperature (RT6) to
(Parameter 159 - FREE COOL SUPPLY SP) which has a
default setting of 55.0°F (13°C).
NOTE: The global input turns on the blower.
a. Set global mode using the Configuration ID 1, position 2,
and set to character G.
b. Connect a jumper between A55_P297-1 (24VAC) and
A55_P297-9 (global). The blower is energized and the
damper will slowly open if discharge air temperature (RT6)
is greater than (Parameter 159 - FREE COOL SUPPLY
SP) which has a default setting of 55.0°F (13°C).
c. Disconnect 24VAC to A55_P297-9. The blower will turn
off and the damper will close.
d. If the damper does not actuate then check all connections
and wiring between P262A and B.
STEP 7. ENTHALPY SENSOR OPERATION (A7 AND
A62)
If enthalpy sensors are configured, current sensor reading
by CORE Unit Controller can be verified through the user
interface:
a. Connect a direct current ammeter as shown in figure 4 to
measure current output of A7 or A62.
b. The reading will be between (4 and 20 ma.) and depends
on outdoor temperature and humidity. Refer to figure 3 to
approximate reading.
DISCONNECT J/P104
PLACE JUMPER WIRE HERE
READ
CURRENT
HERE
-
+
DC AMMETER
Figure 32. Measure A7 and A62 Current in Series
Table 8.
Temp. °F (°C)
50 (10)
60 (16)
Measure A62 Current in Series
TMP Mode Resistor Values
Size Resistor Temp. °F (°C)
19,904 70 (21)
15,313 80 (27)
Go to DATA > SYSTEM DATA / SENSORS / OUTPUTS > LOCAL
(scroll down to INDOOR AND OUTDOOR ENTHALPY)
c. If the meter reads zero, check sensor wiring harness for
continuity and/or check polarity of sensor wiring.

10.5. Demand Control Ventilation

A field-provided and installed indoor air quality (IAQ) sensor
can be used with the modulating economizer or OADM to
control carbon dioxide levels in the conditioned space. The
carbon dioxide level in a space is an indicator of the number
of people occupying a room. As the carbon dioxide level
rises (indicating the occupancy of a room has increased),
dampers modulate open - regardless of outdoor air suitability.
Likewise, as the carbon dioxide level falls (indicating the
occupancy has decreased), dampers modulate further
closed.
Standard economizer installations have a minimum fresh air
ventilation requirement based on maximum room occupancy.
With standard economizer use, the amount of air required
for maximum room occupancy is heated or cooled with each
heating or cooling cycle. IAQ installations use the maximum
amount of required ventilation air only with maximum room
occupancy; less outdoor air needs to be heated or cooled
when fewer people are in the conditioned space.
If the economizer is operating in the free cooling mode and
the indoor air quality control requires the damper to open
further, the indoor air quality demand will override the free
cooling demand.
The IAQ function is not energized during the unoccupied or
night time period.
NOTE:
The IAQ sensor may also be used with systems
containing a motorized outdoor air damper.
32
DISCONNECT J/P105
PLACE JUMPER WIRE HERE
READ
CURRENT
HERE
-
+
DC AMMETER
Size Resistor Temp. °F (°C)
11,884 90 (32)
9,298 100 (38)
INPUTS > SENSORS > LOCAL
Size Resistor
7,332
5,826