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I-EEDU (02-21) 150492-A
CONTROLS—CONTINUED
Pilot and Ignition Systems—Continued
⚠ WARNING ⚠
Do not touch pilot spark wire and pilot electrode when energized due to high voltage.
• If no spark, check the following:
a . Voltage between terminals TH and 7 should be at least 20V and no higher than 32V . Refer to
section if no voltage is observed .
b . Short to ground in the high tension lead and/or ceramic insulator .
c . Pilot spark gap should be approximately 7/64 inch .
d . If the above conditions are normal and no spark occurs, replace the ignition controller .
NOTES:
• When checking for spark with the pilot burner removed from the burner rack, the pilot assembly
must be grounded to the heater for proper spark.
• If replacing an earlier model of ignition controller, order replacement kit (PN 257472 for a unit with
recycling gas control option AH2 or PN 257473 for option AH3 gas control with lockout). Option
codes are listed on the unit wiring diagram.
• Ignition Controller:
• As part of the intermittent safety pilot systems, the ignition controller provides the high voltage spark to ignite
the pilot gas and also acts as the flame safety device .
• After ignition of the pilot gas, the ignition controller electronically senses the pilot flame .
• A low voltage DC electrical signal is imposed on the separate metal probe in the pilot assembly . The metal probe
is electrically insulated from ground .
• The pilot flame acts as a conduction path to ground that completes the DC circuit and proving pilot flame . With
pilot flame proven, the ignition controller energizes the main gas valve .
• Ignition controller with lockout for option AH3 gas control (UTEC #1003-514, PN 257010) is shown in
, DETAIL A .
• Recycling ignition controller for option AH2 gas control (UTEC #1003-638A, PN 257009) is shown in
DETAIL B .
Figure 33. Ignition Controllers
DETAIL A
DETAIL B
