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23. When a CFH occurs, a 24 VAC signal is sent to the
CFH light on the status panel located on the lower
left front of the control compartment.
24. Power is also sent from pin 2 of the stage 1 con-
nection to pin P1-3 of the universal diagnostic
board.
25. Power is now sent to terminal TP4 of the
Economaster II to energize the relay and close the
contacts.
26. Power is waiting at the common terminal of the
flow switch waiting for closure and sufficient water
flow.
27. The heater pump is energized upon relay closure
of the Economaster II.
28. Upon sufficient flow from the heater pump, the
flow switch contacts will close.
29. If there is insufficient flow and the flow switch does
not close, a 24 VAC signal is sent to the Universal
Diagnostics Board to indicate the fault.
30. The flow light is energized; located on the front
status panel.
31. A 24 VAC signal is also sent to the “TH” terminal
located on ignition module one.
32. Once the 24 VAC “TH” signal is received at ignition
module one, the internal contacts between F1 and
F2 close sending a 120 VAC signal to the 120 VAC
pilot duty terminals, located at J14 on the circuit
board.
33. The 120 VAC signal continues to the coil of the
blower relay K-4 (N.O.).
34. The 120 VAC signal continues to the 120 VAC
safety terminals located at J13 on the circuit
board.
35. When the coil on relay K-4 is powered, the N.O.
relay contacts close and energize the blowers
from the J8 connections on the CPW board.
36. After proper air pressure is received in the air
plenum, the air pressure switches will close.
37. If there is insufficient air pressure and the air pres-
sure switch does not close, a 24 VAC signal is sent
to the Universal Diagnostics Board to indicate the
fault.
38. A 24 VAC signal is now sent to the blower LED’s
on the status board.
39. Power is applied to the optional equipment inter-
lock connection (normally jumpered).
40. The 24 VAC signal is then sent to the 24 VAC safe-
ty connector.
41. 24 VAC is now sent to the pressure switch (P.S.)
terminal on the ignition modules.
42. Once the pressure switch signal is received at
ignition module one, the heater performs a 15-sec-
ond pre-purge, then hot surface igniter one is
energized by a 120 VAC signal from S-1 on igni-
tion module one for approximately 30 seconds.
(The hot surface igniter must draw greater than
3.1 amps while being energized or ignition lockout
will occur after three tries.)
43. Once ignition module one determines that hot sur-
face igniter one has heated up and operating
properly, a 24 VAC signal is output from pin GV on
module one.
44. 24 VAC signal is received at gas valve 1 thus ener-
gizing it.
45. The stage 1 LED on the status display board is
now illuminated.
46. The coil of relay K-2 is now energized with the
N.O. contacts closing downstream of the stage 2
and upstream of the stage 3 connections.
47. The gas coming through the burners should ignite
from the heat of hot surface igniter one and the
flame should carry over from one burner to the
other burners of stage 1. Remote flame sensor
one is now trying to sense the flame. If the flame
is not sensed within 4 seconds, the ignition mod-
ule will shut down gas valve 1 and retry hot
surface igniter one. During ignition retry the heater
must perform a 15-second pre-purge and approx-
imately a 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.
48. If ignition module one locks out, a signal will be
sent to the Universal Diagnostics Board and to the
status display board to indicate an ignition fault.