Sequence Of Operation - Honeywell RM7800L1087 Installation Instructions Manual

RELAY MODULES WITH VALVE PROVING
4. PREPURGE Period:
a. Pre-Ignition Interlock opens anytime during
PREPURGE period (except during VP test). (L
model only)
b. Flame signal is detected after first ten seconds
during PREPURGE (RM7800L/40L, EC7840L).
c. High Fire Switch fails to close within four min-
utes and fifteen seconds after the firing rate
motor is commanded to drive to the high fire
position at the start of PREPURGE
(RM7800L/40L, EC7840L).
d. Low Fire Switch fails to close within four minutes
and fifteen seconds after the firing rate motor is
commanded to drive to the low fire position at
the end of PREPURGE.
e. Running Interlock does not close within 30 sec-
onds (RM7840G).
f. Lockout Interlock does not close within 10 sec-
onds (RM7800L/40L, EC7840L).
g. Lockout Interlock opens during PREPURGE
(RM7800L/40L, EC7840L).
h. Ignition/pilot valve/intermittent pilot valve ter-
minal is energized.
i. Main valve terminal is energized (except during
Valve Proving testing).
j. Internal system fault occurred.
5. PILOT FLAME ESTABLISHING Period (PFEP):
a. Low Fire Switch opens.
b. Lockout Interlock opens (RM7800L/40L,
EC7840L).
c. Ignition/pilot valve/intermittent pilot valve ter-
minal is not energized.
d. Early spark termination terminal is energized
after five seconds.
e. No flame is present at the end of PFEP.
f. Main valve terminal is energized (RM7840G).
6. MAIN FLAME ESTABLISHING Period (MFEP):
a. Low Fire Switch opens.
b. Lockout Interlock opens (RM7800L/40L,
EC7840L).
c. Ignition/pilot valve/intermittent pilot valve ter-
minal is not energized.
d. Main valve terminal is not energized.
e. No flame is present at the end of MFEP.
7. RUN Period:
a. No flame is present.
b. Lockout Interlock opens (RM7800L/40L,
EC7840L).
c. Interrupted pilot valve terminal is energized.
d. Main valve terminal is not energized.
8. POSTPURGE Period:
a. Pre-Ignition Interlock does not close in five sec-
onds OR opens after five-seconds during POST-
PURGE period (except during VP testing).
b. Ignition/pilot valve/intermittent pilot valve ter-
minal is energized.
c. Main valve terminal is energized (except during
VP testing).
32-00142—01
OPERATION

Sequence of Operation

The RM7800L/40G,L, EC7840L has the following
operating sequences, see Fig. 4, 5, 7, and 8. The
RM7800L/40L, EC7840L LED provide positive visual
indication of the program sequence: POWER, PILOT,
FLAME, MAIN and ALARM.
Initiate
The RM7800L/40G,L, EC7840L enters the INITIATE
sequence when the Relay Module is powered. The
RM7800L/40G,L, EC7840L can also enter the INITIATE
sequence if the Relay Module verifies voltage fluctuations
of +10/-15 percent or frequency fluctuations of +/-10
percent during any part of the operating sequence. The
INITIATE sequence lasts for ten seconds unless the
voltage or frequency tolerances are not met. When the
tolerances are not met, a hold condition is initiated and
displayed for at least five seconds. When the tolerances
are met, the INITIATE sequence restarts. If the condition is
not corrected and the hold condition exists for four
minutes, the RM7800L/40G,L, EC7840L locks out.
Causes for hold conditions in the INITIATE sequence:
a. AC line dropout is detected.
b. AC line noise prevents a sufficient reading of the
line voltage inputs.
c. Low line voltage brownouts occur.
The INITIATE sequence also delays the burner motor
starter from being energized and de-energized from an
intermittent AC line input or control input.
Standby
The RM7800L/40G,L, EC7840L is ready to start an
operating sequence when the operating control
determines a call for heat is present. (Terminal 6, or
Terminal 17 if Valve Proving is required.) The burner
switch, limits, operating control and all microcomputer
monitored circuits must be in the correct state for the
RM7800L/40G,L, EC7840L to continue into the
PREPURGE sequence.
Prepurge
The ST7800 purge timers provide 15 Pre-Purge timings
selectable from 2 seconds to 30 minutes:
a. The operating control (terminal 6, or terminal 17
for valve proving), Running Interlocks, Pre-Igni-
tion Interlocks, Burner Switch, Run/Test Switch,
Lockout Interlocks and all microcomputer moni-
tored circuits must be in the correct operating
state.
b. The blower motor output, terminal 5, is powered
to start the PREPURGE sequence. The firing rate
motor is driven to the high fire position
(RM7800L/40L, EC7840L). The PREPURGE
timing does not begin until the Lockout Interlock
String and High Fire Switch are both closed.
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