Reznor LDAP Unit Installation Manual - Manual (Page 30)

Form I-LDAP, P/N 207733R6, Page 30
venter motor through post purge, and run the fan motor on heat speed for the
selected delay off time.
Abnormal Heat Cycle Functions (cont’d)
Ignition Retry - If flame is not established on the first trial for ignition period,
the control de-energizes the gas valve and the heat section venter motor and
main venter motor remain energized for an inter-purge period of 10 seconds.
The spark and gas valve are then re-energized, and the control initiates another
trial for ignition.
If flame is not established on the second trial for ignition, the control de-ener-
gizes the gas valve, energizes the fan motor on heat speed, and the heat sec-
tion venter motor and main venter motor remain energized. The fan motor is
shut off after 120 seconds. When the fan motor de-energizes, the spark and
gas valve are re-energized and the control initiates another trial for ignition.
(This fan delay is a self-healing feature for an open auxiliary limit switch).
If flame is not established on the third trial for ignition period, the control de-
energizes the gas valve, and the heat section venter motor and main venter
motor remain energized for an inter-purge period of 10 seconds. The control
then re-energizes the gas valve and spark and initiates another trial for igni-
tion.
If flame is not established on the fourth trial for ignition (initial try plus 3 re-tries),
the control de-energizes the gas valve and goes into lockout. The control goes
to one flash on the green LED to indicate ignition failure lockout.
Limit and High Limit Switch Operation - The high limit and limit switch are
ignored unless a call for heat is present (W energized). If the high limit or limit
switch are open and a call for heat is present, the control de-energizes the gas
valve and turns the fan motor on heat speed and runs the heat section venter
motor and the main venter motor.
When the switch re-closes or the call for heat is lost, the control runs the heat
section venter motor and main venter motor through post purge and runs the
fan motor through the selected fan off delay. The control will return to normal
operation after fan off delay is completed.
Heat Section Pressure Switch (all sizes) and Main Combustion Air Pres-
sure Switch (Sizes 800 and 1200) - If the heat section pressure switch or
main combustion air pressure switch opens before the trial for ignition period,
the heat section venter motor and main venter motor will run through the heat
section pressure switch and main combustion air pressure switch recognition
delay (2 seconds), the gas valve will be de-energized, and the heat section
venter motor and main venter motor will run through the postpurge time. The
control will re-start the heat cycle at the heat section pressure switch and main
combustion air pressure switch proving state if the call for heat still exists.
Heat section pressure switch or main combustion air pressure switch opening
for less than 2 seconds during the trial for ignition period shall not interrupt the
heat cycle. (Gas valve will de-energize while the heat section pressure switch
and main combustion air pressure switch is open.)
If the heat section pressure switch or main combustion air pressure switch
opens after a successful ignition, the control will de-energize the gas valve. If
flame is lost before the end of the 2 second pressure switch recognition delay,
the control will respond to the loss of flame. If the heat section pressure switch
and main combustion air pressure switch remains open for 2 seconds and the
flame remains, the control de-energizes the gas valve, the heat section venter
motor and main venter motor runs through postpurge, and the fan motor runs
on heat speed through the selected fan off delay. When the fan off delay is
8.0 Controls and
Operation
(cont’d)
8.5 Ignition System
(cont’d)