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35. Power is applied to the optional equipment inter-
lock connection (normally jumpered).
36. The 24 VAC signal is then sent to the 24 VAC safe-
ty connector.
37. 24 VAC is now sent to the pressure switch (P.S.)
terminal on the ignition modules.
38. Once the pressure switch signal is received at
ignition module 1, hot surface igniter 1 is ener-
gized by a 120 VAC signal from S-1 on ignition
module 1. (The hot surface igniter must draw
greater than 3.1 amps while being energized or
ignition lockout will occur after three tries.)
39. Once ignition module 1 determines that hot sur-
face igniter 1 has heated up and operating proper-
ly, a 24 VAC signal is output from pin GV on mod-
ule 1.
40. 24 VAC signal is received to gas valve 1 thus ener-
gizing it.
41. The stage 1 LED on the diagnostics display board
is now illuminated.
42. The coil of relay K-2 (N.O.) is now energized with
the (K-2) contacts closing downstream of the
stage 2 connections and upstream of the stage 3
connections.
43. The gas coming through the burners should ignite
from the heat of hot surface igniter 1 and the flame
should carry over from one burner to the other
burners of stage 1. The remote sensor is now try-
ing to sense the flame. If the flame is not sensed
within 4 seconds, the ignition module will shut
down the gas valve and retry the hot surface ignit-
er. During ignition retry the heater must perform a
15-second pre-purge and an approximately 30-
second igniter warm-up before opening gas valve
1 again. The standard ignition module will attempt
ignition a maximum of three times prior to ignition
lockout.
44. After gas valve 1 opens and flame rectification is
received, time delay relay 1 (TD1) starts a 5-sec-
ond countdown.
45. After the 5 second countdown from TD-1, time
delay relay 2 receives 24 VAC.
46. Gas valve 1a is energized allowing the remainder
of stage 1 to fire.
47. After the 5-second countdown from TD-2 the inter-
nal contacts close allowing 24 VAC to sit at pin 3
of the stage 2 connection on the CPW board.
48. The temperature controller closes the stage 2 con-
tacts and gas valve 2 in energized.
49. The stage 2 LED on the diagnostics display board
is now illuminated.
50. The temperature controller closes the stage 3 con-
tacts at J-3 on the CPW board.
51. Power is applied to the “TH” terminal of ignition
module 2.
52. Once the “TH” signal is received at ignition module
2, hot surface igniter 2 is energized by a 120 VAC
signal from S-1 on ignition module 2. (The hot sur-
face igniter must draw greater than 3.1 amps while
being energized or ignition lockout will occur after
three tries.)
53. Once the ignition module determines that the hot
surface igniter has heated up and operating prop-
erly, a 24 VAC signal is output from pin GV on the
module.
54. 24 VAC signal is received at gas valve 3 thus ener-
gizing it.
55. The stage 3 LED on the diagnostics display board
is now illuminated.
56. The coil of relay K-5 (N.O.) is now energized with
the (K-5) contacts closing downstream of the
stage 4 connections.
57. Remote flame sensor 2 is trying to rectify flame.
58. Power is now applied to time delay relay 3 and the
contacts of TD-3 located upstream of the stage 4
connection close after 5 seconds.
59. The stage 4 controller contacts close.
60. Power is applied to gas valve 4.
61. The stage 4 LED on the diagnostics display board
is now illuminated.
62. The heater is now operating at full fire.