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5.4
HIGH and LOW GAS PRESSURE
SWITCHES (Optional)
High and low gas pressure switches are available as an
option and are wired in series with the air flow switch. The
high gas pressure switch is used to monitor the differential
gas pressure between the outlet of the control valve and
the fan inlet. If differential gas pressure exceeds the
maximum setting of the pressure switch, the appliance will
shut down and a low air condition will be indicated on the
display panel. The low gas pressure switch is to monitor the
minimum incoming gas supply pressure supplied to the gas
train. If gas pressure falls below the minimum setting of the
pressure switch, the appliance will shut down and a low air
condition will be displayed on the display panel.
5.5
HIGH LIMIT
A High Limit aqua-stat control is located at the back of the
appliance and the control bulb is installed in a dry well in
the heat exchanger header outlet. The setting of this control
limits maximum discharge water temperature. A manual
reset high limit will have a red reset button which must be
pushed whenever water temperature has exceeded the set
point of the manual reset limit. The temperature of the
water in the heat exchanger must drop a minimum of 15° F
(8.3° C) below the setting of the high limit control before the
reset function can be activated. Whenever an appliance is
supplied with both an auto reset and manual reset high limit
always set the auto reset limit
manual reset limit. This will prevent nuisance tripping of the
manual reset.
5.6
IGNITION CONTROL MODULE
This appliance uses a proven hot surface ignition control
system. The operation of the electronic control module for
the hot surface igniter proves the presence of an ignition
source much like a proven standing pilot before the gas
valves are energized. The ignition control proves the
presence of the proper ignition temperatures from the hot
surface igniter using a proof current (3.2A +/- 0.2),
energizes the main gas valves, proves the presence of
main burner flame, and provides for lockouts. A status point
alarm of Flame Fail will be displayed on the main panel and
also by 3 flashes from the ignition module diagnostic red
LED
Figure 20: Ignition Module
Manual Reset
23
10ºF
(5.5° C) below the
Automatic Reset
5.6.1
SERVICE PARTS
This appliance uses a proved electronic ignition control
module and a hot surface igniter. The electronic ignition
module is not repairable. Any modification or repairs will
invalidate the warranty and may create hazardous
conditions that result in property damage, personal injury,
fire, explosion and/or toxic gases. A faulty hot surface
igniter or ignition module MUST BE replaced with a new
factory approved unit only. A factory approved igniter,
ignition control module and flame sensor for this specific
unit is available from your local distributor. DO NOT use
general purpose field replacement ignition modules, igniters
or sensors. Each appliance has one ignition module, one
hot surface igniter and one flame sensor.
5.6.2
IGNITION MODULE LOCKOUT FUNCTIONS
The ignition module may lockout in either a hard lockout
condition requiring pushing of the reset button to recycle
the control for a CSD1 requirement or a soft lockout
condition which may be reset by momentarily cycling the
main power on and off. A typical hard lockout fault for the 7
seconds one try CSD1 module is a flame failure condition.
Pushing the reset button on the ignition control is the only
way to reset an ignition module that is in a hard lockout
condition. The reset button is located on the front control
panel. The reset button is active after the post purge cycle
when there is a hard lockout condition as indicated by the
Status LED (3 flashes). Turning the main power "OFF" and
then "ON" or cycling the thermostat will not reset a hard
lockout condition. Wait five seconds after turning on the
main power before pushing the reset button when the
ignition module is in a hard lockout. Wait for the status LED
to glow solid red (or green) indicating that the ignition
module is ready before releasing the reset button.
The ignition module will go into a soft lockout with the
standard 5 seconds module after three sequential trials for
ignition separated by 15 seconds between trials. A soft
lockout condition will operate the combustion air fan for the
post purge cycle (maximum 10 minutes) and then go into
lockout and stay in this mode with the air flow light "OFF".
The flame failure and all other lights up to the air flow light
will remain "ON". If the control sensed fault is not corrected,
the ignition module will continue in the soft lockout
condition. A soft lockout condition may be reset by
manually cycling the electronic thermostat or turning the
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