Honeywell 7800 Series Manual page 19

RUN
1. A ten second stabilization period occurs at the
beginning of the RUN period.
2. The firing rate motor releases to modulation
(RM7840E,G,L).
3. The RM7840 is now in RUN and will remain in
RUN until the controller input, terminal 6, opens, indicat-
ing that the demand is satisfied or a limit has opened.
POSTPURGE
The RM7840 provides a fifteen second POSTPURGE
following the completion of the RUN period. The blower
Fig. 17—RM7840E,L sequence.
INITIATE STANDBY
POWER
LED
DISPLAY
BURNER
OPERATING
CONTROLS
AND
INTERLOCK. CHECK
INTERLOCKS
1
FLAME
SIGNAL
FIRING
RATE
MOTOR
1
FOR THE RM7840E: THE HIGH FIRE SWITCH MUST BE WIRED CORRECTLY TO PERFORM ENERGY SAVING PURGE
FUNCTIONS. THE BURNER/BLOWER MOTOR DOES NOT START UNTIL THE HIGH FIRE SWITCH HAS BEEN MADE.
PREPURGE
00 00 00
DRIVE TO TIMED
HIGH FIRE PURGE
POWER POWER POWER
PILOT
FLAME
MAIN
ALARM
BURNER/BLOWER MOTOR
1
LIMITS AND BURNER CONTROLLER CLOSED
LOCKOUT INTERLOCKS CLOSED
PREIGNITION INTERLOCK CLOSED
5 TO 19 HIGH FIRE SW.
SAFE START CHECK
RM7800E,L SWITCHING
13 12
TO
MOTOR ACTION
motor output is powered to drive all combustion products
and any unburned fuel from the combustion chamber. It
also supplies combustion air to burn fuel being purged
from the fuel line downstream of the fuel shutoff valve.
1. The main fuel valve and intermittent pilot valve,
terminals 9 and 21, are de-energized and the firing rate
motor is commanded to the low fire position to begin the
POSTPURGE period.
2. The Preignition Interlock closes within the first five
seconds of POSTPURGE.
3. After the fifteen second POSTPURGE period is
completed, the RM7840 reenters STANDBY.
RM7840E,L
PREPURGE
00 10 20
DRIVE TO
PFEP
LOW FIRE
4 OR 10 SEC
MFEP
POWER
POWER POWER
PILOT
PILOT PILOT
FLAME FLAME
FLAME
MAIN MAIN
MAIN
ALARM
ALARM ALARM
10 IGN. 5 SEC.
10 SEC. IGN./PILOT 8
15 SEC. PILOT 21
MAIN VALVE
L1 TO
6 TO
TO
4 20
5 18
LOW FIRE SW. TO
FLAME PROVING
13 14
TO
19
RM7840E,G,L,M
25 00 15
RUN POSTPURGE
STANDBY
POWER POWER POWER
PILOT
FLAME
MAIN
ALARM
5
9
6
7 IC
PII
SSC
13 15
TO
13 TO 14
M3357
65-0087—2
OPERATION