Honeywell 7800 SERIES User manual

7800 SERIES RM7840E,G,L,M
Relay Module
■Safety features:
—Interlock check.
—Closed loop logic test.
—Dynamic AMPLI-CHECK™.
—Dynamic input check.
—Dynamic safety relay test.
—Dynamic self-check logic.
—Expanded safe-start check.
—High Fire Purge Switch test.
—Internal hardware status monitoring.
—Low Fire Start Switch test.
—Tamper resistant timing and logic.
■Access for external electrical voltage checks.
■Application flexibility.
■Communication interface capability.
■Dependable, long-term operation provided by microcom-
puter technology .
■First-out annunciation and system diagnostics are pro-
videdbyanoptional2rowby20columnVacuumFluores-
cent Display (VFD) located on the Keyboard Display
Module (optional).
■First-out expanded annunciation with 26 Light Emitting
Diodes (LEDs) for limits and interlocks (optional).
■Five LEDs for sequence information.
■Five function Run/Test Switch.
■Interchangeable plug-in flame amplifiers.
■Local or remote annunciation of RM7840 operation and
fault information.
■Nonvolatile memory RM7840 retains history files and
sequencing status after loss of power.
■Remote reset (optional).
■Report generation (optional).
■Burner controller data (optional):
—Expanded annunciator status.
—Flame signal strength.
—Hold status.
—Lockout/alarm status.
—Sequence status.
—Sequence time.
—Total cycles of operation.
—Total hours of operation.
—Fault history, providing for the six most recent
faults:
• Cycles of operation at the time of the fault.
• Expanded annunciator data at the time of the fault.
• Fault message and code.
• Hours of operation at the time of the fault.
• Sequence status at the time of the fault.
• Sequence time at the time of the fault.
—Diagnostic information:
• Device type.
• Flame amplifier type.
• Flame failure response time.
• Manufacturing code.
• On/Off status of all digital inputs and outputs.
• Selected prepurge time.
• Software revision and version of RM7840 and
optional Keyboard Display Module.
• Status of configuration jumpers.
• Status of Run/Test Switch.
The Honeywell RM7840 is a microprocessor
based integrated burner control for automatically
fired gas, oil, or combination fuel single burner ap-
plications. The RM7840 consists of a Relay Module.
Subbase, Amplifier and Purge Card are required to
complete the system. Options include Keyboard Dis-
play Module, Personal Computer Interface, DATA
CONTROLBUS MODULE™, Remote Display
Mounting, First-Out Expanded Annunciator and
COMBUSTION SYSTEM MANAGER™ software.
The RM7840 is programmed to provide a level of
safety, functional capability and features beyond the
capacity of conventional controls.
Functions provided by the RM7840 include auto-
matic burner sequencing, flame supervision, system
status indication, system or self-diagnostics and
troubleshooting.
CONTENTS
Specifications ................................................2
Ordering Information.................................... 2
Principle Technical Features ........................ 7
Safety Provisions........................................... 8
Installation .................................................... 9
Wiring.......................................................... 11
Assembly...................................................... 15
Operation .................................................... 18
Static Checkout............................................ 22
Checkout...................................................... 24
Troubleshooting .......................................... 32
S. H. • Rev. 9-92 • ©Honeywell Inc. 1992 • Form Number 65-0087—2

2
RM7840E,G,L,M
SPECIFICATIONS • ORDERING INFORMATION
Specifications
ELECTRICAL RATINGS (See Table 1):
VoltageandFrequency: 120 Vac(+10/-15%),50or 60
Hz (+/- 10%). 5
Power Dissipation: RM7840: 10W maximum.
Maximum Total Connected Load: 2000 VA.
Fusing: Total Connected Load: 20A maximum, type
FRN or equivalent.
When purchasing replacement and modernization products from your 7800 SERIES distributor, refer to the TRADELINE® Catalog for complete
ordering number.
If you have additional questions, need further information, or would like to comment on our products or services, please write or phone:
1. Your local Home and Building Control Sales Office (check white pages of your phone directory).
2. Home and Building Control Customer Satisfaction
Honeywell Inc., 1885 Douglas Drive North
Minneapolis, Minnesota 55422-4386 [phone]
InCanada—HoneywellLimited/HoneywellLimitee,740EllesmereRoad,Scarborough,OntarioM1P2V9InternationalSalesandServiceOffices
in all principal cities of the world. Manufacturing in Australia, Canada, Finland, France, Germany, Japan, Mexico, Netherlands, Spain, Taiwan,
United Kingdom, U.S.A.
Ordering Information
TABLE 1—TERMINAL RATINGS.
Terminal No. Description Ratings
G Flame Sensor Ground1
Earth G Earth Ground1
L2(N) Line Voltage Common
3 Alarm 120 Vac, 1A pilot duty.
4 Line Voltage Supply (L1) 120 Vac (+10/-15%), 50 or 60 Hz (+/- 10%).2,3
5 Burner Motor 120 Vac, 9.8 AFL, 58.8 ALR (inrush).
6 Burner Controller and Limits 120 Vac, 1 mA.
7 Lockout/Running Interlock 120 Vac, 9A.
8 Pilot Valve/Ignition 120 Vac, 4.5A Ignition and 50VA pilot duty.3
9 Main Fuel Valve 120 Vac, 2A pilot duty.4
10 Ignition 120 Vac, 4.5A Ignition.3
F(11) Flame Sensor 60 to 220 Vac, current limited.
12 Firing Rate High Fire 120 Vac, 75 VA pilot duty.
13 Firing Rate Common 120 Vac, 75 VA pilot duty.
14 Firing Rate Low Fire 120 Vac, 75 VA pilot duty.
15 Firing Rate Modulate 120 Vac, 75 VA pilot duty.
16 Unused
17 Unused
18 Low Fire Switch Input 120 Vac, 1 mA.
19 High Fire Switch Input 120 Vac, 1 mA.
20 Preignition Interlock Input 120 Vac, 1 mA.
21 Interrupted/Intermittent Pilot Valve/
First Stage Oil Valve 120 Vac, 2A pilot duty.
22 Shutter 120 Vac, 0.5A.
1The RM7840 must have an earth ground providing a connection between the subbase and the control panel or the equipment.
The earth ground wire must be capable of conducting the current to blow the 20A fuse (or breaker) in event of an internal short
circuit.The RM7840 needsa lowimpedance groundconnectionto theequipment framewhich, in turn,needs alow impedance
connection to earth ground. For a ground path to be low impedance at RF frequencies, the connection must be made with
minimum length conductors that have maximum surface areas. Wide straps or brackets rather than leadwires are preferred. Be
careful to ensure that mechanically tightened joints along the ground path, such as pipe or conduit threads or surfaces held
together with fasteners, are free of nonconductive coatings and are protected against mating surface corrosion.
22000 VA maximum connected load to RM7840 Assembly.
3Can also be 120 Vac, 1A pilot duty.
4Can also be 65 VA pilot duty with motorized valve, 1150 VA inrush, 460 VA open, 250 VA hold.
5Operating frequency chosen by RM7840 selection.

RM7840E,G,L,M
SPECIFICATIONS
3 65-0087—2
ENVIRONMENTAL RATINGS:
Ambient Temperature:
Operating: -40°F to 140°F.
Storage: -40°F to 150°F.
Humidity: 85% RH continuous, noncondensing.
Vibration: 0.5G environment.
DIMENSIONS: Refer to Figs. 1 and 2.
WEIGHT:RM7840 withDustCover: 1 pound13ounces,
unpacked.
IMPORTANT: Flame Detection System available for
use with RM7840. To select your Plug-in Flame
SignalAmplifierand matching FlameDetector,see
Table 2.
TABLE 2—FLAME DETECTION SYSTEMS (Figs. 3, 4, 5)
Plug-in Flame Signal Amplifiers Applicable Flame Detectors
Flame
Failure
Self- Response
Type Color Checking Model Time Fuel Type Models
Rectification Green No R7847A .8 or 3 sec Gas Rectifying C7004,
Flame Rod C7007,
HoldersdC7011.
CompleteAssemblies:
C7008, C7009, Q179.
No R7847A .8 or 3 sec Oil Rectifying C7003, C7010,
Photocell C7013, C7014.e
No R7847A 3 sec Gas, oil, Ultraviolet C7012A,C.a
coal (PurplePeeper)
Dynamic R7847Bc.8 or 3 sec Gas Rectifying C7004, C7007,
AMPLI- Flame Rod C7011.
CHECK™ HoldersdComplete Assemblies:
C7008, C7009, Q179.
Dynamic R7847Bc.8 or 3 sec Oil Rectifying C7003, C7010,
AMPLI- Photocell C7013, C7014.e
CHECK™
Dynamic R7847Bc3 sec Gas, oil, Ultraviolet C7012A,C.a
AMPLI- coal (Purple
CHECK™ Peeper)
Dynamic R7847Cb3 sec Gas, oil, Ultraviolet C7012E,F.
Self- coal (Purple
Check Peeper)
Infrared Red No R7848A 3 sec Gas, oil, Infrared C7015.
coal (Lead Sulfide)
Dynamic R7848Bc3 sec Gas, oil Infrared C7015.
AMPLI- coal (Lead Sulfide)
CHECK™
Ultraviolet Purple No R7849A .8 or 3 sec Gas, oil Ultraviolet C7027, C7035,
(Minipeeper) C7044.a
Dynamic R7849Bc.8 or 3 sec Gas, oil Ultrviolet C7027, C7035,
AMPLI- (Minipeeper) C7044.a
CHECK™
Blue Dynamic R7886Ab3 sec Gas, oil, Ultraviolet C7076.
Self- coal (Adjustable
Check Sensitivity)
aThe C7012A,C, C7027, C7035 and C7044 flame detectors should be used only on burners that cycle on-off at least
once every twenty-four hours. Appliances with burners that remain on for twenty-four hours continuously or longer
should use the C7012E,F Flame Detector with the R7847C Amplifier or the C7076A Flame Detector with the
R7886A Amplifier as the ultraviolet flame detection system.
bCircuitry tests all electronic components in the flame detection system (amplifier and detector) 12 times a minute
during burner operation and shuts down the burner if the detection system fails.
cCircuitry tests the flame signal amplifier at least 12 times a minute during burner operation and shuts down the
burner if the amplifier fails.
dOrder flame rod separately; see holder Instructions.
eUse only Honeywell Photocell, part no. 38316.

RM7840E,G,L,M
SPECIFICATION
SEQUENCE TIMING FOR NORMAL OPERATION
Post Firing Energy Approval
Flame Establishing Period Purge Interlock Rate Saving Code
Device Initiate Standby Purge Pilot Main Run Timing Circuits Circuit Prepurge Bodies
RM7840E 10 sec. * ** 4 or 10 sec. 10 or 15 sec. * 15 sec. Preignition, 4-wire Yes FM/IRI
Lockout, modulating Modulating
High and
Low Fire
RM7840G 10 sec. * ** 4 or 10 sec. 10, 15 sec. or * 15 sec. Preignition, No UL/CSA
Intermittent Running, Modulating
Low Fire
RM7840L 10 sec. * ** 4 or10 sec. 10 or 15 sec. * 15 sec. Preignition, No FM/IRI
Lockout, Modulating
High and
Low Fire
RM7840M 10 sec. * ** 4 or 10 sec. 10 sec. or * 15 sec. Preignition, 2-wire No UL/CSA
Intermittent Running, isoltated On-Off
Low Fire On-Off-On
contacts
* STANDBY and RUN can be an infinite time period.
** PURGE will be determined by which ST7800A purge card is selected.
1The MFEP will be determined by which terminal used, configuration jumper selected or jumper wire added, see
Figs. 7, 8, 9, 10, and 21.
APPROVAL BODIES:
UnderwritersLaboratoriesInc.listed,FileNo.MP268,
Guide No. MCCZ.
Canadian Standards Association certified, LR9S329-
3.
Factory Mutual approved: Report No. J11V9A0.AF.
IRI acceptable.
Federal Communications Commission: Part 15, Class
B—Emissions.
Communication Interface Base Unit—part no.
Q7700A1014.
Communication Interface ControlBus Module—
part no. QS7800A1001.
DATA CONTROLBUS MODULE™—part no.
S7810A1009.
Dust Cover—part no. 221729A.
Expanded Annunciator—part no. S7830A1005.
Flame Simulators:
part no. 203659 UV Flame Simulator.
part no. 123514A Rectification Simulator.
KeyboardDisplayModule—part no. S7800A1001.
Remote Display Mounting Bracket—part no.
203765.
Remote Display Power Supply—part no. 203968A
Plug-in.
Remote Reset Module—part no. S7820A1007.
Sixty-inch Cable Assembly—part no. 221818A.
Tester—part no. A7800A1002.
4
MOUNTING: Q7800A for panel mount or Q7800B for
wall or burner mount.
REQUIRED COMPONENTS:
Plug-in Flame Signal Amplifier, see Table 2.
Plug-in Purge Timer Cards: selectable ST7800A: two
seconds to 30 minutes.
Q7800A or Q7800B
ACCESSORIES:
Optional:
ControlBus 5-Wire Electrical Connector—part no.
203541.
COMBUSTIONSYSTEMMANAGER™—partno.
ZM7850A1001.
Fig. 1—Mounting dimensions of RM7840 Relay Module and Q7800A Subbase, in inches [millimeters].
POWER
PILOT
FLAME
MAIN
ALARM
RESET
5
[127]
5 [127]
M5003A
5 [133]
1
4
BURNER CONTROL
REMOVE ONLY FOR TERMINAL TEST ACCESS.
1
1

1 [32]
1
4
1
[45]
3
4
[21]
13
16 1 [35]
3
8
1 [33]
5
16 5
16 [8]1 [32]
1
4
2
[51]
C7013A C7014A M1847
RM7840E,G,L,M
SPECIFICATIONS
5 65-0087—2
MOUNTING FLANGE
7 [183]
7
32
3
[87]
7
16
3
[95]
3
4
5
[130]
1
8
5 [133]
1
4
1/2–14 NPSM
LEADWIRES FACEPLATE
3/4–14 NPT OR
1–11-1/2 NPT
M1962
THREADED
MOUNTING
HOLES (2)–
10-32 UNF
[13]
1
2
1 [25]
FLAME ROD
[18]
11
16
3
8[10]
[2]
3
32
[20]
25
32 [20]
25
32 [14]
17
32
TARGET
2 [62]
25
32
1
[27]
1
16
1
[36]
13
32
1
[42]
21
32
3
[79]
1
8
CERAMIC
INSULATORS
IGNITION
ELECTRODE
(Q179C ONLY)
BRACKET M1983
Q179 C7012A,C,E,F
Fig. 3—Rectification detectors.
POWER
PILOT
FLAME
MAIN
ALARM
RESET
5
[127]
5 [127]
M5004A
6 [155]
3
32
BURNER CONTROL
REMOVE ONLY FOR TERMINAL TEST ACCESS.
1
1
Fig. 2—Mounting dimensions of RM7840 Relay Module and Q7800B Subbase, in inches [millimeters].

RM7840E,G,L,M
SPECIFICATIONS
6
Fig. 4—Ultraviolet detectors.
C7027 C7035
1
[27]
1
16
COLLAR WITH 1/2-14 NPSM
INTERNAL THREADS
4 [102]
3 [89]
1
2
6 FOOT [1.83 METER]
LEADWIRES (2)
M1943A
MODEL AVAILABLE WITH 24 FOOT [7.32 METER] LEADWIRES.
MODELS AVAILABLE WITH SPUD CONNECTOR (1/2-14 NPSM INTERNAL
THREADS
)
INSTEAD OF CLAMP TYPE CONNECTOR.
1
2
1
2
1
[38]
1
231
32
[25]
1/2-14 NPSM
INTERNAL THREADS
4 [105]
1
8
2
1
[30]
3
16
2 [51]
COLLAR WITH
1–11-1/2 NPSM
INTERNAL
THREADS 1
1DIN APPROVED C7035A1064 HAS 1-11 BSP.P1 INTERNAL THREADS.
DIN APPROVED C7035A1064 HAS 1/2-14 BSP-F INTERNAL THREADS.
MODEL AVAILABLE WITH 12 FOOT [3.66 METER] LEADWIRES.
2 [67]
5
8
2
3
INSERTION DEPTH
6 FOOT
[1.83 METER]
LEADWIRES (2) 3
M1945A
C7044
[22]
7
8
3 [92]
5
8
1
2[13]
9
16 [14]
1 [36]
27
64
[10]
3
8
MOUNTING BRACKET
6 FOOT [1.83 METER]
LEADWIRES (2)
M1944A
C7015
1
[32]
1
4
2 [70]
3
4
APERTURE
BUSHING WITH
MAGNIFYING LENS COLLAR, 3/4-14 NPSM
INTERNAL THREADS
3/4-14
NPSM 3/4-14 NPSM
INTERNAL
THREADS
1
[32]
1
4
1 [27]
1
16
1 [41]
5
8
HEAT BLOCKCELL MOUNT
M1982A
2 LEADS IN A
48 INCH [1.2 METER]
FLEXIBLE CONDUIT
Fig. 5—Infrared detector.

RM7840E,G,L,M
PRINCIPAL TECHNICAL FEATURES
Principal Technical Features
7 65-0087—2
The RM7840 provides all customary flame safeguard
functions while supplying significant advancements in
the areas of safety, annunciation and system diagnostics.
SAFETY SHUTDOWN (LOCKOUT) OCCURS IF:
1. INITIATE Period
a. Purge card is not installed or removed.
b. Purge card is bad.
c. Configurationjumpershavebeen changed (after
200 hours).
d. AC line power errors occurred, see Operation.
e. FourminuteINITIATEperiodhasbeenexceeded.
2. STANDBY Period
a. Flame signal is present after 40 seconds.
b. Preignition Interlock is open an accumulative
time of 30 seconds.
c. Interlock check feature is enabled and the Inter-
lock String (including airflow switch) is closed
for 120 seconds with controller closed.
d. Ignition/pilot valve/intermittent pilot valve ter-
minal is energized.
e. Main valve terminal is energized.
f. Internal system fault occurred.
g. Purge card is not installed or removed.
h. Purge card is bad.
3. PREPURGE Period
a. Preignition Interlock opens anytime during
PREPURGE period (RM7840E,L).
b. Flame signal is detected after first ten seconds
during PREPURGE (RM7840E,L).
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
positionatthestartofPREPURGE(RM7840E,L).
d. Low Fire Switch fails to close within four min-
utes 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,M).
f. Lockout Interlock does not close within 10 sec-
onds (RM7840E,L).
g. Lockout Interlock opens during PREPURGE
(RM7840E,L).
h. Ignition/pilot valve/intermittent pilot valve ter-
minal is energized.
i. Main valve terminal is energized.
j. Internal system fault occurred.
k. Purge card is removed.
l. Purge card is bad.
4. PILOT FLAME ESTABLISHING Period (PFEP)
a. Low Fire Switch opens.
b. Lockout Interlock opens (RM7840E,L).
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 end of PFEP.
f. Mainvalveterminalisenergized(RM7800G,M).
g. Internal system fault occurred.
h. Purge card is removed.
i. Purge card is bad.
5. MAIN FLAME ESTABLISHING Period (MFEP)
a. Low Fire Switch opens.
b. Lockout Interlock opens (RM7840E,L).
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 end of MFEP.
f. Internal system fault occurred.
g. Purge card is removed.
h. Purge card is bad.
6. RUN Period
a. No flame is present.
b. Lockout Interlock opens (RM7840E,L).
c. Interrupted pilot valve terminal is energized
(RM7840G,M).
d. Main valve terminal is not energized.
e. Internal system fault occurred.
f. Purge card is removed.
g. Purge card is bad.
7. POSTPURGE Period
a. Preignition Interlock does not close in five sec-
onds and opens after five-second time period.
b. Ignition/pilot valve/intermittent pilot valve ter-
minal is energized.
c. Main valve terminal is energized.
d. Internal system fault occurred.
e. Purge card is removed.
f. Purge card is bad.

RM7840E,G,L,M
SAFETY PROVISIONS
8
Safety Provisions
INTERNAL HARDWARE STATUS MONITORING
The RM7840 checks the purge card for correct parity to
prevent purge timing shifts and circuitry failures. It also
analyzes the integrity of the configuration jumpers and
internal hardware. The POWER LED will blink every four
seconds, signifying an internal hardware check.
CLOSED LOOP LOGIC TEST
The test verifies the integrity of all safety critical loads,
terminals 8, 9, 10 and 21. If the loads are not energized
properly; i.e., the main valve terminal is powered during
PREPURGE, theRM7840willlockout on safetyshutdown.
The RM7840 must react to input changes but avoid the
occurrenceofnuisance shutdownevents.Signalcondition-
ing is applied to line voltage inputs to verify proper opera-
tion in the presence of normal electrical line noise such as
transient high voltage spikes or short periods of line drop-
out. Signal conditioning is tolerant of synchronous noise
(line noise events that occur at the same time during each
line cycle).
DYNAMIC AMPLI-CHECK™
Dynamic AMPLI-CHECK™ circuitry tests the flame
signal amplifier during burner operation and shuts down the
RM7840 if the flame amplifier fails.
DYNAMIC FLAME AMPLIFIER AND SHUTTER
CHECK
Self-checking circuitry tests all electronic components
in the flame detection system and amplifier 10 to 12 times
per minute and shuts down the RM7840 if the detection
system fails.
DYNAMIC INPUT CHECK
All system input circuits are examined to verify the
RM7840iscapableof recognizing thetruestatusof external
controls, limits and interlocks. If any input fails this test, a
safety shutdown occurs and the fault is annunciated.
DYNAMIC SAFETY RELAY TEST
Checks the ability of the dynamic safety relay contacts to
open and close. Verifies that the safety critical loads, termi-
nals 8, 9, 10 and 21, can be de-energized, as required, by the
Dynamic Self-Check logic.
DYNAMIC SELF-CHECK SAFETY CIRCUIT
Themicrocomputertestsitselfandrelatedhardwarewhile
at the same time the safety relay system tests the microcom-
puter operation. If a microcomputer or safety relay failure
occursand doesnotallowproperexecutionoftheself-check
routine, safety shutdown will occur and all safety critical
loads will be de-energized.
EXPANDED SAFE-START CHECK
Theconventionalsafe-startcheck,whichpreventsburner
start-upifflameisindicatedatstart-up,isexpandedtoinclude
a flame signal check during STANDBY, a preignition inter-
lock check, an interlock check, and a safety critical load
check.
HIGH FIRE PURGE AND LOW FIRE START
SWITCH TESTS
HighFirePurge Switch Test(RM7840E,L)examines the
PurgePositionInterlockSwitchatthemomentthefiringrate
motoris commandedtothehighfireposition.Iftheswitchis
bypassed, welded or otherwise closed prematurely, the sys-
tem will automatically add 30 seconds to allow additional
drive time for the firing rate motor to reach or near the open
position before starting the purge timing; otherwise, purge
timingstartswhentheHighFireSwitchisclosed.Thisswitch
will also cause a hold (four minutes, fifteen seconds) condi-
tion when the switch is open before purge or opens during
purge. The RM7840E,L will lockout and annunciate an
alarm if the switch fails to close within the hold time period.
Low Fire Start Switch Test examines the Low Fire Start
Switch at the moment PREPURGE is completed. If the
switchisbypassed,weldedor otherwiseprematurelyclosed,
the system will automatically add 30 seconds to allow the
firing rate motor additional time to reach or near the low fire
start position before ignition trials; otherwise, ignition trials
startaftertheLowFire Switchcloses.Thetestalso isusedto
provethatthefiringratemotorisatlowfirepositionthrough-
outtheignitiontrialperiod.Thisswitchalsowillcauseahold
(four minutes, fifteen seconds) condition if the switch opens
after purging is complete. The RM7840 will lockout and
annunciateanalarmiftheswitchfailstoclosewithinthehold
time period.
MANDATORY PURGE
If lockout occurs after the initiation of ignition trials (or
at any-time during a sequence when the fuel valves may
have been energized), a mandatory POSTPURGE period
is imposed.
OFF CYCLE (STANDBY OR PREPURGE) FLAME
SIGNAL CHECK
Theflamedetectionsubsystem(flamedetectorandampli-
fier) is monitored during STANDBY. If a flame simulating
conditionoran actualflameexists,a systemholdoccurs and
start-up is prevented. If the flame signal exists at any time
after the first 40 seconds of STANDBY, a safety shutdown
willoccurandbeannunciated.Ashutter-checkamplifierand
self-checking detector are energized for the first 40 seconds
during STANDBY and the last two seconds before exiting
STANDBY. Ifaflameexists, a safety shutdownoccurs.An
AMPLI-CHECK™ Amplifier is energized continually
throughSTANDBYandPREPURGEtodetectanypossibil-
ity of a runaway detector or a flame. If either situation
happens, a safety shutdown occurs. A standard amplifier is
energizedcontinuallythroughSTANDBYandPREPURGE.
If either situation happens, a safety shutdown occurs.

RM7840E,G,L,M
SAFETY PROVISIONS
9 65-0087—2
PREIGNITION OUTPUT CIRCUIT CHECK
At the end of PREPURGE, the Dynamic Safety Relay
operation is checked. Also, all safety critical loads termi-
nals8,9,10and 21,arecheckedtoverify theterminalsare
not powered. If the Dynamic Safety Relay operation is
faulty, or if any of the safety critical loads are powered,
safety shutdown occurs and is annunciated.
TAMPER RESISTANT TIMING AND LOGIC
Safetyandlogictimingsareinaccessibleandcannotbe
altered or defeated.
VERIFIED SPARK TERMINATION
Theignitionterminalismonitoredtoverifyearlyspark
termination (five seconds ignition and pilot and five
seconds pilot only).
FIRST-OUT ANNUNCIATION AND
SELF-DIAGNOSTICS
Sequence Status Lights (LEDs) provide positive visual
indication of the program sequence: POWER, PILOT,
FLAME, MAIN and ALARM. The green POWER LED
blinks every four seconds, signifying that the RM7840
hardware is running correctly.
Optional multi-function Keyboard Display Module
shows elapsed time during PREPURGE, PILOT IGN,
MAIN IGN,and POSTPURGE.Asan additionaltrouble-
shooting aid, it provides sequence timing, diagnostic
information, historical information and expanded annun-
ciator information when a safety shutdown or hold or
normal operation occurs.
First-out Annunciation reports the cause of a safety
shutdown or identifies the cause of a failure to start or
continue the burner control sequence with an English text
and numbered code via the optional Keyboard Display
Module. It monitors all field input circuits, including the
flame signal amplifier and firing rate position switches.
Thesystemdistinguishes118modesoffailureanddetects
and annunciates difficult-to-find intermittent failures.
Self-Diagnostics adds to the First-out Annunciation
by allowing the RM7840 to distinguish between field
(external device) and internal (system related) prob-
lems. Faults associated within the flame detection sub-
system, RM7840 or Plug-in Purge Card, are isolated
and reported by the optional Keyboard Display Mod-
ule, see the 7800 SERIES System Annunciation Diag-
nostics and Troubleshooting, form 65-0118.
INTERLOCK REQUIREMENTS
The following interlock inputs are provided:
Low Fire Interlock (RM7840 ALL)
Thisinterlockverifiesthefiringratemotorisinthelow
fire position before and during ignition trials.
High Fire Interlock (RM7840E,L)
This interlock verifies the firing rate motor is in the
high fire position before and during PREPURGE. If the
High Fire Switch is jumpered on the RM7840E, the
Energy Saving function will not be performed.
Running Interlock (RM7840G,M)
This interlock (ILK) input signifies a Running Inter-
lock. If a Running Interlock is open at the beginning of
PREPURGE,a30secondholdconditionisinitiated.If30
seconds elapse and the Running Interlock still has not
closed, a lockout will occur. After entering PREPURGE,
iftheRunningInterlockopensduringthefirsttenseconds,
the purge timer will be reset. This provides a continuous
PURGE to occur without interruption before the Pilot
FlameEstablishingPeriod.IftheRunningInterlockopens
after ten seconds into PREPURGE, it will recycle back to
the beginning of PREPURGE. If it opens anytime during
theIgnitionTrialsorRun,itwillproceedtoPOSTPURGE.
Atypical RunningInterlock stringcontains anAirflow
Switch (see Fig. 9 and 11). The Interlock Check is a site
configurable option (see Table 6). If this feature is en-
abled, the RM7840 will lockout after 120 seconds when-
ever control terminal 6 is energized, and the Running
Interlock string (including Airflow Switch) is closed dur-
ing STANDBY.
Lockout Interlock (RM7840E,L)
This interlock (ILK) input signifies a Lockout Inter-
lock. If the Lockout Interlock is open for more than ten
seconds into PREPURGE, the RM7800E,L will lockout.
AfterenteringPREPURGE,iftheLockoutInterlockopens
during the first ten seconds, the purge timer will be reset.
This provides a continuous PURGE to occur without
interruptionbeforethePilotFlame EstablishingPeriod.If
a Lockout Interlock opens anytime after ten seconds into
PURGE, during the Ignition Trials or Run, it causes a
lockout.
AtypicalLockoutInterlock string contains an Airflow
Switch (see Figs. 8 and 10). The Interlock Check is a site
configurable option (see Table 6). If this feature is en-
abled, the RM7840 will lockout after 120 seconds when-
ever control terminal 6 is energized, and the Lockout
Interlock string (including Airflow Switch) is closed dur-
ing STANDBY.
NOTE:FortheRM7840E,the tensecondtimeframedoes
not begin until the blower motor is recognized.
Preignition Interlock (RM7840 ALL)
The Preignition Interlock input is typically connected
to a proof-of-closure switch for a fuel valve(s). The
Preignition Interlock must be energized throughout
PREPURGE. If the Preignition Interlock opens during
STANDBY, it causes a hold (30 seconds). The RM7840
will lockout if the interlock does not close within 30
seconds during STANDBY. If the Preignition Interlock
opens during PREPURGE, it will recycle to STANDBY
(RM7840G,M) or will lockout (RM7840E,L). If the Pre-
ignition Interlock is open after five seconds into
POSTPURGE,theRM7840willlockout. ThePreignition
Interlock is ignored during the ignition trials state and
during RUN.

RM7840E,G,L,M
INSTALLATION
10
CONFIGURATION
JUMPERS
MICROCOMPUTER
RESET
PUSHBUTTON
RUN/TEST
SWITCH
STATUS LEDs
PLUG-IN PURGE
TIMER CARD
SAFETY RELAY
CIRCUIT
POWER SUPPLY
KEYBOARD
DISPLAY MODULE
HIGH FIRE
COMMON
MODULATE
LOW FIRE
HIGH FIRE SWITCH
PLUG-IN
FLAME
AMPLIFIER
RELAY
DRIVE
CIRCUIT
CONTROL
POWER
TEST
JACK
REMOTE
RESET
DDL
DDL
COMMUNICATIONS
INDICATES FEEDBACK SENSING
TO RELAY STATUS FEEDBACK
AND LINE VOLT INPUTS
FIELD WIRING
INTERNAL WIRING
IGNITION
PILOT
PILOT/V2
MAIN VALVE
1K
9K
RELAY
STATUS
FEEDBACK
AND LINE
VOLTAGE
INPUTS
LIMITS CONTROLLER
RUNNING/
LOCKOUT
INTERLOCK
PRE-IGNITION
INTERLOCK
1K1 2K1 5K1
8K1
8K2
9K1
9K2
120 Vac
FLAME SIGNAL
TEST
LOW FIRE SWITCH
PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
RS485
123
L1
(HOT) L2
4
6
20
7
4K1
7K1
2K2
10
8
21
9
18
19
8K
7K
6K
5K
4K
3K
2K
F
G
22
1
BLOWER
6K1 5
ALARM
3K1 3
L2
12
13
15
14
1
M1925
Fig. 6—Internal block diagram of RM7840 (see Figs. 7, 8, 9 or 10 for detailed wiring instructions).
WHEN INSTALLING THIS PRODUCT…
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a hazardous
condition.
2. Checktheratingsgivenintheinstructionsandmarked
on the product to make sure the product is suitable for your
application.
3. Installer must be a trained, experienced, flame safe-
guard service technician.
4. After installation is complete, check out the product
operation as provided in these instructions.
Installation
WARNING
FIRE OR EXPLOSION HAZARD
CAN CAUSE PROPERTY DAMAGE,
SERVERE INJURY, OR DEATH
To prevent possible hazardous burner operation,
verificationofsafety requirementsmustbe per-
formed each time a control is installed on a
burner.
!

RM7840E,G,L,M
INSTALLATION • WIRING
11 65-0087—2
CAUTION
1. Disconnect the power supply before beginning
installation to prevent electrical shock, equip-
mentandcontroldamage.Morethanonepower
supply disconnect may be involved.
2. WiringconnectionsfortheRM7840areunique;
therefore, refer to Figs. 6,7,8,9or10or the cor-
rect Specifications for proper subbase wiring.
3. Wiring must comply with all applicable codes,
ordinances and regulations.
4. Wiring,whererequired,mustcomplywithNEC,
Class 1 (Line Voltage) wiring.
5. Loads connected to the RM7840 must not ex-
ceed those listed on the RM7840 label or the
Specifications, see Table 1.
6. Limitsandinterlocks must be ratedtocarry and
break current simultaneously to the ignition
transformer,pilot valve,andmainfuelvalve(s).
7. Allexternaltimersmust be listed orcomponent
recognizedby authoritieswhohave jurisdiction
forthespecificpurposeforwhichtheyareused.
IMPORTANT:
1. For on-off gas-fired systems, some authorities who
have jurisdiction prohibit the wiring of any limit or
operating contacts in series between the flame safe-
guard control and the main fuel valve(s).
2. Two detectors can be connected in parallel with the
exception of Infrared detectors (C7015A).
3. This equipment generates, uses and can radiate radio
frequency energy and, if not installed and used in
accordance with the instructions, may cause interfer-
ence to radio communications. It has been tested and
foundtocomplywiththelimitsforaClassBcomputing
device of Part 15 of FCC rules, which are designed to
provide reasonable protection against such interfer-
ence when operated in a commercial environment.
Operation of this equipment in a residential area may
cause interference; in which case, the users at their
own expense may be required to take whatever mea-
sures are required to correct this interference.
4. This digital apparatus does not exceed the Class B
limitsforradionoiseof digitalapparatussetoutin the
Radio Interference Regulations of the Canadian De-
partment of Communications.
HUMIDITY
Install the RM7840 where the relative humidity never
reaches the saturation point. The RM7840 is designed to
operateinamaximum85%RHcontinuous,noncondensing,
moisture environment. Condensing moisture may cause a
safety shutdown.
VIBRATION
Do not install the RM7840 where it could be subjected to
vibration in excess of 0.5G continuous maximum vibration.
WEATHER
The RM7840 is not designed to be weather tight. If
installed outdoors, the RM7840 must be protected by an
approved weather-tight enclosure.
MOUNTING WIRING SUBBASE
NOTE: For installation dimensions, see Figs. 1 or 2.
1. Mountthesubbaseinanypositionexcept horizontally
with the bifurcated contacts pointing down. The standard
vertical position is recommended. Any other position de-
creases the maximum ambient temperature rating.
2. Select a location on a wall, burner or electrical
panel. The Q7800 can be mounted directly in the control
cabinet.Besuretoallowadequateclearanceforservicing,
installation, access and removal of the RM7840, Dust
Cover, flame amplifier, flame amplifier signal voltage
probes, Run/Test Switch, electrical signal voltage probes
and electrical field connections.
3. For surface mounting, use the back of the subbase
as a template to mark the four screw locations. Drill the
pilot holes.
4. Securely mount the subbase using four no. 6 screws.
Wiring
may be involved.
3. Allwiringmustcomply with all appropriate electrical
codes, ordinances and regulations. Wiring, where required,
must comply with NEC, Class 1 (Line Voltage) wiring.
4. Recommended wire size and type:
a. All line voltage terminals use no.14, 16, or18cop-
perconductor(TTW60CorTHW75CorTHHN90C)
600 volt insulation wire. For high temperature
installations, use wire selected for a temperature
rating above the maximum operating temperature.
All leadwires should be moisture resistant.
1. a. For proper subbase wiring, refer to Figs 7, 8, 9,
or 10.
b. For proper remote wiring of the Keyboard Display
Module, refer to the Specifications for the Key-
board Display Module (65-0090), Communica-
tionInterfaceBaseUnit(63-2278),DATACON-
TROLS MODULE™ (65-0091) or Extension
Cable Assembly (65-0131).
2. Disconnect the power supply from the main discon-
nect before beginning installation to prevent electrical
shock and equipment damage. More than one disconnect
!

RM7840E,G,L,M
WIRING
5. Recommended grounding practices:
a. Use the earth ground to provide a connection
between the subbase and the control panel or the
equipment. The earth ground wire must be ca-
pable of conducting the current to blow the
20A fuse (or breaker) in event of an internal
short circuit. The RM7840 needs a low imped-
ance ground connection to the equipment frame
which, in turn, needs a low impedance connec-
tion to earth ground. For a ground path to be low
impedance at RF frequencies, the connection
must be made with minimum length conductors
that have a maximum surface area. Wide straps
or brackets are preferred rather than leadwires.
Be careful to ensure that mechanicallytightened
joints along the ground path, such as pipe or
conduit threads or surfaces held together with
fasteners, are free of nonconductive coatings and
are protected against mating surface corrosion.
b. Each RM7840 has an earth ground terminal that
mustbe groundedtothemetalcontrolpanelwith
wireas shortaspractical.Eachgroundwiremust
becapableof carryingafault currentequalto the
rating of the protective fuse (20A). A number 14
copper conductor is adequate but wide straps or
brackets are preferred rather than leadwires.
6. Recommended wire routing:
a. Flame detector leadwires:
12
M1977A
G
L
2
3
4
5
6
7
8
9
1
0
F
(L1
)
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
1
2
LOCKOUT INTERLOCKS
(INC. AIR FLOW SWITCH)
MASTER
SWITCH
LOW FIRE
START SWITCH
HIGH FIRE
PURGE SWITCH
5 SECOND IGNITION
(EARLY SPARK
TERMINATION)
MAIN FUEL
VALVE(S)
BURNER
CONTROLLER/LIMITS
BURNER MOTOR
(BLOWER)
HIGH FIRE
COMMON
LOW FIRE
MODULATE
120V ALARM
10 SEC. INTERRUPTED
PILOT/IGNITION
PREIGNITION
INTERLOCK
SERIES 90
FIRING RATE
MOTOR SERIES 90
CONTROLLER
RECTIFYING FLAME
ROD, RECTIFYING
PHOTOCELL, OR INFRA-
RED (LEAD SULFIDE)
FLAME DETECTOR
C7027A, C7035A, OR
C7044A ULTRAVIOLET
FLAME DETECTOR
C7012A,C,E,F OR
C7076A,D ULTRAVIOLET
FLAME DETECTOR
120V, 60 Hz POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
DO NOT WIRE TO ANY UNUSED TERMINALS.
FOR DIRECT SPARK IGNITION (OIL
OR GAS)
IGNITION
TRANSFORMER
MAIN VALVE
R
W
B
R
W
B
L1
(HOT)
L2 1
OR
OR
BLUE
BLUE
WHITE
YELLOW
L2
WHITE
WHITE
BLACK
BLACK L1
L2
8
9
1
0
L
2
1
Q7800
15 SECOND
INTERRUPTED
PILOT VALVE
2
2
Fig. 7—Wiring RM7840E.

RM7840E,G,L,M
WIRING
13 65-0087—2
1. Do not run high voltage ignition transformer
wires in the same conduit with the flame detec-
tion wiring.
2. Do not route scanner wires in conduit with line
voltage circuits.
3. Enclose scanner wires without armor cable in
metal cable or conduit.
4. Follow directions given in the flame detector
Instructions.
7. Maximum wire lengths:
a. For RM7840, the maximum length of leadwire is
300 feet to terminal inputs (Control, Preignition
Interlock, Running/Lockout Interlock, High Fire
Switch and Low Fire Switch).
M1978
A
G
L
2
3
4
5
6
7
8
9
1
0
F
(L1
)
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
1
2
RUNNING INTERLOCKS
(INC. AIR FLOW SWITCH)
MASTER
SWITCH
LOW FIRE
START SWITCH
5 SECOND IGNITION
(EARLY SPARK
TERMINATION)
MAIN FUEL
VALVE(S)
BURNER
CONTROLLER/LIMITS
BURNER MOTOR
(BLOWER)
HIGH FIRE
COMMON
LOW FIRE
MODULATE
120V ALARM
10 SEC. INTERRUPTED
PILOT/IGNITION
PREIGNITION
INTERLOCK
SERIES 90
FIRING RATE
MOTOR SERIES 90
CONTROLLER
RECTIFYING FLAME
ROD, RECTIFYING
PHOTOCELL, OR INFRA-
RED (LEAD SULFIDE)
FLAME DETECTOR
C7027A, C7035A, OR
C7044A ULTRAVIOLET
FLAME DETECTOR
C7012A,C,E,F OR
C7076A,D ULTRAVIOLET
FLAME DETECTOR
120V, 60 Hz POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
MAIN FLAME ESTABLISHING PERIOD (MFEP).
DO NOT WIRE TO ANY UNUSED TERMINALS.
FOR DIRECT SPARK IGNITION (OIL
OR GAS)
IGNITION
TRANSFORMER
2ND STAGE
FUEL VALVE
(OPTIONAL)
R
W
B
R
W
B
L1
(HOT)
L2 1
OR
OR
BLUE
BLUE
WHITE
YELLOW
L2
WHITE
WHITE
BLACK
BLACK L1
L2
2
1
9
1
0
L
2
1
Q7800
JUMPER WIRE FOR 30s MFEP
2
15 OR 30 SEC.
INTERRUPTED/
INTERMITTENT
PILOT VALVE
1ST STAGE
FUEL VALVE
2
3
3
b. For flame detector leadwires, the maximum flame
sensorleadwirelengthislimitedbytheflamesignal
strength.
8. Make sure loads do not exceed the terminal ratings.
Refer to the label on the RM7840 or to the ratings in
Specifications, see Table 1.
9. Check the power supply circuit. The voltage and
frequency tolerance must match those of the RM7840. A
separatepowersupplycircuitmayberequiredfortheRM7840.
Addtherequireddisconnectmeans andoverloadprotection.
10. Check all wiring circuits and complete Static Check-
out, see Table 4, before installing the RM7840 on the
subbase.
11. Install all electrical connectors.
12. Restore power to the panel.
Fig. 8—Wiring RM7840G.

RM7840E,G,L,M
WIRING
14
Fig. 9—Wiring RM7840L.
M1979A
G
L
2
3
4
5
6
7
8
9
1
0
F
(L1
)
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
1
2
LOCKOUT INTERLOCKS
(INC. AIR FLOW SWITCH)
MASTER
SWITCH
LOW FIRE
START SWITCH
HIGH FIRE
PURGE SWITCH
5 SECOND IGNITION
(EARLY SPARK
TERMINATION)
MAIN FUEL
VALVE(S)
BURNER
CONTROLLER/LIMITS
BURNER MOTOR
(BLOWER)
HIGH FIRE
COMMON
LOW FIRE
MODULATE
120V ALARM
10 SEC. INTERRUPTED
PILOT/IGNITION
PREIGNITION
INTERLOCK
SERIES 90
FIRING RATE
MOTOR SERIES 90
CONTROLLER
RECTIFYING FLAME
ROD, RECTIFYING
PHOTOCELL, OR INFRA-
RED (LEAD SULFIDE)
FLAME DETECTOR
C7027A, C7035A, OR
C7044A ULTRAVIOLET
FLAME DETECTOR
C7012A,C,E,F OR
C7076A,D ULTRAVIOLET
FLAME DETECTOR
120V, 60 Hz POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
DO NOT WIRE TO ANY UNUSED TERMINALS.
FOR DIRECT SPARK IGNITION (OIL
OR GAS)
IGNITION
TRANSFORMER
MAIN VALVE
R
W
B
R
W
B
L1
(HOT)
L2 1
OR
OR
BLUE
BLUE
WHITE
YELLOW
L2
WHITE
WHITE
BLACK
BLACK L1
L2
8
9
1
0
L
2
1
Q7800
15 SECOND
INTERRUPTED
PILOT VALVE
2
2

RM7840E,G,L,M
WIRING • ASSEMBLY
15 65-0087—2
Fig. 10—Wiring RM7840M.
MOUNTING RM7840
NOTE: For installation dimensions, see Figs. 1 or 2.
RELAY MODULE MOUNTING
1. Mount the RM7840 vertically, see Figs. 11 or 12, or
mount horizontally with the knife blade terminals pointing
downward. When mounted on the Q7800A, the RM7840
must be in an electrical enclosure.
2. Select the location in the electrical enclosure. Be sure
to allow adequate clearance for servicing, installation and
removaloftheRM7840,DustCover,flameamplifier,flame
amplifier signal voltage probes, electrical signal voltage
probes and electrical connections.
a. AllowanadditionaltwoinchesbelowtheRM7840
for the flame amplifier mounting.
b. Allowanoptionalthree-inchminimumtobothsides
of the RM7840 for electrical signal voltage probes.
Assembly
M1980B
G
L
2
3
4
5
6
7
8
9
1
0
F
(L1
)
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
1
2
RUNNING INTERLOCKS
(INC. AIR FLOW SWITCH)
MASTER
SWITCH
LOW FIRE
START SWITCH
5 SECOND IGNITION
(EARLY SPARK
TERMINATION)
MAIN FUEL
VALVE(S)
BURNER
CONTROLLER/LIMITS
BURNER MOTOR
(BLOWER)
COMMON
MODULATE
120V ALARM
10 SEC. INTERRUPTED
PILOT/IGNITION
PREIGNITION
INTERLOCK
DAMPER
MOTOR
RECTIFYING FLAME
ROD, RECTIFYING
PHOTOCELL, OR INFRA-
RED (LEAD SULFIDE)
FLAME DETECTOR
C7027A, C7035A, OR
C7044A ULTRAVIOLET
FLAME DETECTOR
C7012A,C,E,F OR
C7076A,D ULTRAVIOLET
FLAME DETECTOR
120V, 60 Hz POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
WHEN NO DAMPER MOTOR OR LOW FIRE SWITCH IS USED, JUMPER TERMINAL 14 TO TERMINAL 18, AND DO NOT
WIRE TERMINAL 15.
DO NOT WIRE TO ANY UNUSED TERMINALS.
FOR DIRECT SPARK IGNITION (OIL
OR GAS)
IGNITION
TRANSFORMER
2ND STAGE
FUEL VALVE
(OPTIONAL)
L1
(HOT)
L2 1
OR
OR
BLUE
BLUE
WHITE
YELLOW
L2
WHITE
WHITE
BLACK
BLACK L1
L2
2
1
9
1
0
L
2
1
Q7800
INTERMITTENT
PILOT
1ST STAGE
FUEL VALVE
T
O
2
2
2
2
3
3

RM7840E,G,L,M
ASSEMBLY
16
3. Makesurenosubbase wiring is projectingbeyondthe
terminal blocks. Tuck wiring in against the back of the
subbasesoitdoesnotinterferewiththeknifebladeterminals
or bifurcated contacts.
IMPORTANT: The 7840 must be installed with a plug-in
motion rather than a hinge action.
4. Mount the RM7840 by aligning the four L shaped
corner guides and knife blade terminals with the bifurcated
contactsonthewiringsubbaseandtighteningthetwoscrews
securely without deforming the plastic.
INSTALLING ST7800 PURGE CARD
1. Removethe Dust Cover,KeyboardDisplay Module,
DATA CONTROLBUS MODULE™ or Extension Cable
Assembly.
2. Remove the current ST7800 from the RM7840 by
pulling upward on the plastic support cover.
3. Makesure theST7800 selectedhas thedesired timing.
4. Insert the Purge Card into the opening of the RM7840
compartment, see Fig. 13.
5. Reinstall the Dust Cover, Keyboard Display Module,
DATA CONTROLBUS MODULE™ or Extension Cable
Assembly ontotheRM7840andrestorepowertothedevice.
6. Run the burner system through at least one complete
cycle to verify the system is operating as desired.
MOUNTING DUST COVER
1. Alignthetwointerlockingearsofthe DustCoverwith
the two mating slots on the RM7840, see Fig. 14.
2. Insert the two interlocking ears into the two mating
slotsand,withahingeaction,pushontheuppercornersofthe
Dust Cover to secure it to the RM7840.
3. Be sure the Dust Cover is firmly in place.
Fig. 14—Dust Cover mounting.
Fig. 11—Electrical panel installation.
Fig. 13—ST7800 Purge Card installation.
Fig. 12—Wall or burner installation.

RM7840E,G,L,M
ASSEMBLY
17 65-0087—2
Fig. 16—Flame
detector wiring.
M1969
1FLAME DETECTOR LEADS ARE COLOR CODED. THE BLUE LEAD MUST BE CONNECTED TO THE F TERMINAL AND THE WHITE
MUST BE CONNECTED TO THE G TERMINAL. THE UV SENSING TUBE IS POLARITY SENSITIVE. REVERSING THE LEADS EVEN
MOMENTARILY, CAN DAMAGE OR DESTROY THE UV TUBE.
FLAME DETECTOR LEADS ARE COLOR CODED. THE BLUE LEAD MUST BE CONNECTED TO THE F TERMINAL AND THE YELLOW
MUST BE CONNECTED TO THE G TERMINAL. THE UV SENSING TUBE IS POLARITY SENSITIVE. REVERSING THE LEADS EVEN
MOMENTARILY, CAN DAMAGE OR DESTROY THE UV TUBE.
2
BLUE
YELLOW
WHITE
WHITE
BLACK
BLACK
F
G
22
L2
L1
L2
BLUE
WHITE
F
G
WHITE
BROWN
F
G
INFRARED (C7015)
ULTRAVIOLET (C7027/C7035/C7044)
SOLID STATE SELF-CHECKING
ULTRAVIOLET (C7012E,F)
BLUE
YELLOW
BLACK
BLACK
F
G
L1
L2
SOLID STATE
ULTRAVIOLET (C7012A,C)
1
22
F G
4
5
3
L2
C7076A,D ULTRAVIOLET DETECTOR
522
6
SHUTTER
G
SHUTTER
F
1
8
2
7
7800 SERIES
L1
L2
3a 3b
REMOTE
SENSOR
2b
2a
EARTH
GROUND
C7076A
OR
C7076D
TERMINAL
BLOCK
L2 (COMMON)
L1 (HOT)
G
F
X
X
FLAME ROD
G
F
X
X
PHOTOCELL
the keyed receptacle on the RM7840. Verify the amplifier
nameplate faces away from the Relay Module, see Fig. 15.
3. Push in the amplifier until the circuit board is fully
inserted into the receptacle and then push the amplifier
toward the RM7840 retaining clasp.
4. Verify the amplifier is firmly in place.
5. Perform all required checkout tests.
INSTALLING FLAME DETECTOR
NOTE:Table2liststheflamedetectionsystemsavailablefor
usewiththeRM7840.Makesurethecorrectcombination
of amplifier and flame detector(s) is used.
Properflamedetectorinstallationisthebasisofasafeand
reliableflamesafeguardinstallation.RefertotheInstructions
packed with the flame detector and the equipment manufac-
turer instructions, see Fig. 16.
Keeptheflame signal leadwiresasshortas possible from
the flame detector to the wiring subbase. Capacitance in-
creases with leadwire length, reducing the signal strength.
The maximum permissible leadwire length depends on the
type of flame detector, leadwire and conduit. The ultimate
limiting factor in the flame detector leadwire is the flame
signal, see Table 6.
INSTALLING PLUG-IN FLAME SIGNAL
AMPLIFIER
1. Disconnect the power supply before beginning instal-
lation to prevent electrical shock and equipment damage.
More than one disconnect may be involved.
2. Align the amplifier circuit board edge connector with
Fig. 15—Flame signal amplifier mounting.

Operation
18
RM7840E,G,L,M
OPERATION
Sequence of Operation
The RM7840 has the following operating sequences, see
Figs. 17, 18 , 19 and 20.
INITIATE
The RM78040 enters the INITIATE sequence when the
Relay Module is powered. The RM7840 can also enter the
INITIATE sequence if the Relay Module verifies voltage
fluctuationsof+10/-15%orfrequencyflucuationsof+/-10%
during any part of the operating sequence. The INITIATE
sequencelastsfortensecondsunlessthevoltageorfrequency
tolerances are not met. When the tolerances are not met,
a hold condition will be initiated for at least five seconds.
When the tolerances are met, the INITIATE sequence will
restart. If the condition is not corrected and hold condition
existsforfourminutes,the RM7840willlockout.Causesfor
hold conditions in the INITIATE sequence:
a. AC line dropout is detected.
b. AClinefrequencyerrorcausedbyusinga60Hzdevice
on a 50 Hz line, or vice versa.
c. AC line noise that can prevent a sufficient reading of
the line voltage inputs.
d. Brownouts caused by low line voltage.
The INITIATE sequence also delays the burner motor
starterfrombeingenergizedand de-energizedfromaninter-
mittent AC line input or control input.
STANDBY
TheRM7840isreadytostartanoperatingsequencewhen
the operating control input determines a call for heat is
present.Theburnerswitch,limits,operatinglimitcontroland
all microcomputer monitored circuits must be in the correct
state for the RM7840 to continue into the PREPURGE
sequence.
NORMAL START-UP PREPURGE
The RM7840 provides a selectable PREPURGE timing
from two seconds to 30 minutes with power applied and the
RM7840 operating control indicating a call for heat.
a. Running Interlocks, Preignition Interlocks, Burner
Switch, Run/Test Switch, Lockout Interlocks and all
microcomputer monitored circuits must be in the cor-
rect operating state.
b. The blower motor output, terminal 5, is powered to
start the PREPURGE sequence, except for the
RM7840E. The firing rate motor is driven to the high
fire position. The PREPURGE timing for the
RM7840E,L does not begin until the Lockout Inter-
lock string and High Fire Switch are both closed. The
blowermotoroutputfortheRM7840Eisnotenergized
until the High Fire Switch is closed.
c. The Preignition Interlock input must remain closed
throughout PREPURGE; otherwise, the control re-
turns to the STANDBY state and holds (30 seconds)
for the RM7840G,M or safety shutdown for the
RM7840E,L occurs.
d. The Lockout Interlock or Running Interlock inputs
(interlockcircuitincludingAirflowSwitch)mustclose
by ten seconds or within specified purge card timing
intoPREPURGE; otherwise, a hold or recycle back
to the beginning of PREPURGE for the RM7840G,M
will happen or a safety shutdown for the RM7840E,L
occurs.
e. After the firing rate motor reaches the PREPURGE
ratepositionandPREPURGEtimingiscompleted,the
firing rate motor will drive to the low fire position,
RM7840E,G,L.
f. When the firing rate motor reaches low fire position,
the Low Fire Switch, terminal 18, input must be
energized before entering the Ignition Trial state.
IGNITION TRIALS
a. Pilot Flame Establishing Period (PFEP):
1. With the firing rate motor in the low fire position:
a. The pilot valve and ignition transformer, termi-
nals8,10and21,areenergized.TheRM7840M
has an intermittent pilot valve, terminal 21. The
RM7840G has an interrupted or intermittent
pilotvalve,terminal21,dependingontheselec-
tion of configuration jumper JR2. The
RM7840E,L has a fifteen second interrupted
pilot valve, terminal 21. All the RM7840s have
a ten second interrupted pilot valve/ignition,
terminal 8.
b. During the PFEP, the Low Fire Switch must re-
mainclosed.Ifitopens,asafetyshutdownoccurs.
c. The Preignition Interlock input is ignored
throughout the Ignition Trial state.
2. Flame must be proven by the end of the four or ten
second PFEP to allow the sequence to continue. If
flame is not proven by the end of PFEP, a safety
shutdown occurs.
3. Withflameproven,the ignition, terminal10,isde-
energized for early spark termination.
b. Main Flame Establishing Period (MFEP):
1. The RM7840E,L has a ten second or fifteen
second MFEP. After the Ignition Trials, and with
thepresenceofflame,themainfuelvalve,terminal
9, is powered. If a flameout occurs, the RM7840
will lockout within .8 or 3 seconds, depending on
the Flame Failure Response Time (FFRT) of the
amplifier.
2. TheRM7840Ghasatensecondorfifteensecondor
thirty second MFEP. After the Ignition Trials, and
with the presence of flame, the main fuel valve,
terminal 9, is powered. If a flameout occurs, the
RM7840 will lockout within .8 or 3 seconds, de-
pending on the FFRT of the amplifier.
3. The RM7840M has a ten second MFEP. After the
Ignition Trials, and with the presence of flame, the
main fuel valve, terminal 9, is powered. If a flame-
out occurs, the RM7840 will lockout within .8 or 3
seconds, depending on the FFRT of the amplifier.

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
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. ThePreignition Interlockcloseswithinthefirstfive
seconds of POSTPURGE.
3. After the fifteen second POSTPURGE period is
completed, the RM7840 reenters STANDBY.
19 65-0087—2
RM7840E,G,L,M
OPERATION
Fig. 17—RM7840E,L sequence.
RM7840E,L
POWER
00
OPERATING
CONTROLS
AND
INTERLOCKS
BURNER
FLAME
SIGNAL
FIRING
RATE
MOTOR
INITIATE
POWER
STANDBY
POWER
PREPURGE
DRIVE TO
HIGH FIRE
POWER
PILOT
FLAME
MAIN
POWER
PFEP
4 OR 10 SEC
PILOT
FLAME
MAIN
POWER
MFEP
PILOT
FLAME
MAIN
RUN
POWER
POSTPURGE
POWER
STANDBY
00 00 10 25 00 1520
RM7800E,L SWITCHING
MOTOR ACTION
BURNER/BLOWER MOTOR
IGN.
15 SEC. PILOT
LIMITS AND BURNER CONTROLLER CLOSED
LOCKOUT INTERLOCKS CLOSED
PREIGNITION INTERLOCK CLOSED
LOW FIRE SW.
SAFE START CHECK FLAME PROVING
10 SEC. IGN./PILOT 8
10
5
5 SEC.
21
6
TO
7TO
20
TO
518
TO
13 15
TO
13 12
TO
M3357
INTERLOCK. CHECK
HIGH FIRE SW.
19
TO
13 14
TO 13 14
TO
5
4
6
L1
MAIN VALVE 9
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.
1
1
1
TIMED
PURGE
POWER
FLAME
MAIN
PILOT
ALARM
POWER
FLAME
MAIN
PILOT
ALARM
ALARMALARMALARM
PREPURGE
DRIVE TO
LOW FIRE 00
IC
PII
SSC
LED
DISPLAY

RM7840E,G,L,M
OPERATION
20
Fig. 18—RM7840G sequence.
Fig. 19—RM7840M sequence.
RM7840M
POWER
00
OPERATING
CONTROLS
AND
INTERLOCKS
BURNER
FLAME
SIGNAL
FIRING
RATE
MOTOR
INITIATE
POWER
STANDBY
POWER
PREPURGE
POWER
PILOT
FLAME
MAIN
POWER
PFEP
4 OR 10 SEC
PILOT
FLAME
MAIN
POWER
MFEP
PILOT
FLAME
MAIN
POWER
RUN
FLAME
MAIN
POWER
POSTPURGE
POWER
STANDBY
00 00 10 25 00 1520
RM7840M SWITCHING
MOTOR ACTION
BURNER/BLOWER MOTOR
IGN.
10 SEC. IGN./PILOT
INTERMITTENT PILOT VALVE
MAIN VALVE
LIMITS AND BURNER CONTROLLER CLOSED
RUNNING INTERLOCKS CLOSED
PREIGNITION INTERLOCK CLOSED
LOW FIRE SW.
SAFE START CHECK FLAME PROVING
21
8
10
5
5 SEC.
9
L1 6
TO
67
TO
420
TO
518
TO
13 15
TO
13 15
TO
M3358
INTERLOCK CHECK
PILOT
ALARM
ALARM
ALARM
ALARM
TIMED
PURGE
LED
DISPLAY
IC
PII
SSC
RM7840G
POWER
00
OPERATING
CONTROLS
AND
INTERLOCKS
BURNER
FLAME
SIGNAL
FIRING
RATE
MOTOR
INITIATE
ALARM
POWER
STANDBY
POWER
PREPURGE
POWER
PILOT
FLAME
MAIN
POWER
PFEP
4 OR 10 SEC
PILOT
FLAME
MAIN
POWER
MFEP
PILOT
FLAME
MAIN
POWER
RUN
FLAME
MAIN
POWER
POSTPURGE
POWER
STANDBY
00 00 10 25 00 1520
RM7800G SWITCHING
MOTOR ACTION
BURNER/BLOWER MOTOR
IGN.
10 SEC. IGN./PILOT
15/30 SEC. INTERRUPTED/INTERMITTENT PILOT VALVE
MAIN VALVE
LIMITS AND BURNER CONTROLLER CLOSED
RUNNING INTERLOCKS CLOSED
PREIGNITION INTERLOCK CLOSED
LOW FIRE SW.
SAFE START CHECK FLAME PROVING
21
8
10
5
5 SEC.
9
L1 6TO
6 7
TO
420
TO
5 18
TO
13 15TO
13 12TO
M3360
INTERLOCK CHECK
13 14TO 13 14
TO
40
PILOT
AAA
TIMED
PURGE
ALARM ALARM ALARM
LED
DISPLAY
IC
PII
SSC