Guardian 2.0 LP or Natural Gas Heater
Owner’s Manual • Guardian 2.0
23
Refer to the system operation sequence in this section to
gain an understanding as to how the equipment oper-
ates during a call for heat. Understanding the operation
sequence of the ignition module and related components is
essential as it will relate directly to problem solving provided
by the flow charts.
The ignition control module has a self diagnostic feature.
If the heater has a problem, the control module will flash a
specific pattern.
To effectively use the flow charts, you must first identify
what the problem is by the flashing pattern of the red diag
-
nostic light. If the light is flashing, the flash pattern will be
followed by a pause and then a repeat of the flash pattern
until the problem is corrected.
Refer to the tables below to identify what page to refer to
when troubleshooting any problems.
Page
Diagnostic light is NOT ON during a call for heat .......24
Diagnostic light is ON during a call for heat ................25
L.E.D. diagnostic light flashing:
A. Rapid Flash (AW model)
........................................25
B. One Time................................................................25
C. Two Times ..............................................................26
D. Three Times ...........................................................27
E. Four Times .............................................................28
F. Five Times ..............................................................28
G. Smart Sense Troubleshooting ...............................28
Components should be replaced only after each step has
been completed and replacement is suggested in the flow
chart.
SEQUENCES OF OPERATION:
-- The RED LED will not be ON during normal
operation.
-- Line voltage is sent to transformer
-- Transformer terminal branches off line voltage to ignition
control terminal 120VAC.
-- (Smart Sense) 0-10 VDC, 0-20 mA, or 4-20 mA signal is
sent to signal conditioner from building controller.
-- (Smart Sense) Signal conditioner changes the building
controller input signal to 0-15 VDC which is sent to the
variable rate gas control valve.
-- Transformer reduces line voltage to 24 VAC.
-- If applicable, 24 VAC is sent to the thermostat.
-- Thermostat closes and returns the 24 VAC to the
ignition control terminal 24 VAC.
-- Ignition control sends flame sense current to the flame
sensor rod on terminal FS.
-- Ignition control module performs self safety check.
-- Air pressure circuit is tested
-- Control sends 24 VAC from terminal PSI to air pressure
switch.
-- Ignition control module begins ignition trial sequence.
-- Ignition control sends 120 volts from terminal
MOTOR to the heater motor. (Model AW325: Ignition control
sends 120 volts to motor relay coil. The relay contact closes
and sends 120 volts to start the motor.
-- Motor starts.
-- Air pressure switch closes and 24 VAC is
returned to terminal PSO of ignition control.
(AW models)
-- Motor stops
-- Ignition control module sends 120 volts to hot surface igniter
-- Igniter reaches ignition temperature in 17 seconds.
-- Ignition control restarts the motor.
(AD models)
-- Ignition control powers the igniter and igniter sparks.
(Both)
-- Ignition control sends 24 VAC from terminal GV to high limit
switch.
-- If limit switch contact is closed, limit sends 24 VAC to gas
control valve
-- Gas control valve opens
-- Ignition occurs.
-- Flame sense current is passed through burner flame back to
ignition control.
-- Igniter stays powered until ignition control proves flame
sense
-- Igniter then shuts down.
-- Gas control valve stays open
-- Room warms to desired temperature.
-- Thermostat is satisfied.
-- Heater shuts down.
-- Process starts again on a call for heat.
THERE ARE 3 IGNITION TRIALS:
AW Models:
-- 3 ignition trials occur within 90 seconds
AD Models:
-- 3 ignition trials occur within 45 seconds
Both:
-- If no ignition, the control board goes into a lock-out with a
3-flash code.
-- To retry, turn heater off and on.
DIAGNOSTICE LED IS ON DURING A CALL
FOR HEAT:
-- Either the air pressure switch circuit is closed or remains
open during a call for HEAT.
-- One minute soft lockout interval, 2 more ignition attempts.
-- If the problem persist after the 3rd attempts, a 1-flash or
2-flash code will be display by the LED. See page 24 & 25
for flash code.
