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27
Low Ambient Control (Factory Option)
If the unit comes with Electro-Mechanical (EM) control,
then no adjustment is necessary.
If the unit comes with PremierLink™ or RTU Open con-
trol option, then refer to its installation control manual for de-
tails on adjusting “Cooling Lock-Out” setting and configure
for the specific job requirements.
Integrated Gas Controller
This unit contains an Integrated Gas Controller (IGC)
board. The IGC control board uses a flue gas pressure switch
that senses pressure drop in the heat exchanger due to the
combustion inducer. See Fig. 45.
Fig. 45 — Flue Gas Pressure Switch and Pressure
Sense Tube (Typical Location)
When the thermostat calls for heating, power is sent to W
on the Integrated Gas Controller (IGC) board. An LED (light
emitting diode) on the IGC board turns on and remains on
during normal operation. A check is made to ensure that the
rollout switch and limit switch are closed, and that the pres-
sure switch is open. If the check was successful, the induced
draft motor is energized. When the pressure in the heat ex-
changer is low enough to close the pressure switch, the igni-
tion activation period begins. Once ignition occurs, the IGC
board will continue to monitor the condition of the rollout
switch, the limit switches, the pressure switch, and the flame
sensor. Assuming the unit is controlled through a room ther-
mostat set for “fan auto,” 45 seconds after ignition occurs, the
indoor fan motor will energize, and the outdoor air dampers
will open to their minimum position. If the “over temperature
limit” opens prior to the start of the indoor fan blower, the
IGC will shut down the burners, and the control will shorten
the 45 second delay to 5 seconds less than the time to tip the
limit. For example, if the limit trips at 37 seconds, the control
will change the “fan on delay” from 45 seconds to 32 sec-
onds. Once the “fan on delay” has been modified, it will not
change back to 45 seconds unless power is reset to the con-
trol. On units with 2 stages of heat, W2 closes and initiates
power to the second stage of the main gas valve when addi-
tional heat is required.
When the thermostat is satisfied, W1 and W2 open and the
gas valve closes, interrupting the flow of gas to the main
burners. If the call for W1 lasted less than 1 minute, the heat-
ing cycle will not terminate until 1 minute after W1 became
active. If the unit is controlled through a room thermostat set
for fan auto, the indoor fan motor will continue to operate for
an additional 45 seconds, then stop. An LED indicator is pro-
vided on the IGC to monitor operation.
See Fig. 46 for IGC board component layout. Figure 47 is
a typical IGC control wiring diagram.
FLUE GA
S
PRE
SS
URE
S
WITCH
FLUE GA
S
PRE
SS
URE
S
EN
S
E TUBE
Summary of Contents for WeatherMaker 48KC Series
Page 4: ...4 Fig 2 Unit Dimensional Drawing ...
Page 5: ...5 Fig 2 Unit Dimensional Drawing cont ...
Page 23: ...23 Fig 41 Typical Humidi MiZer Adaptive Dehumidification System Humidistat Wiring ...
Page 25: ...25 Fig 43 Typical Control Wiring Diagram Electro Mechanical with W7212 ...
Page 26: ...26 Fig 44 Typical 48KC 04 06 Power Wiring Diagram 208 230 3 60 Unit Shown ...