PF X4-400 User manual

X4 AND X4M INSTALLATION
AND
OPERATION MANUAL

Table of Contents
General Information............................................................................................................................2
Capacities & Specifications.................................................................................................................2
Acceptance Procedures......................................................................................................................2
Installation........................................................................................................................................2-4
Gas Piping.......................................................................................................................................4-6
Wiring.................................................................................................................................................7
Start Up.........................................................................................................................................7-11
Combustion Arrangement Requirements.....................................................................................11-12
Service/Maintenance Suggestions...............................................................................................12-13
Burner PartsList..........................................................................................................................13-14
Sequenceof Operationfor X4MBurners..........................................................................................16
X4M Wiring Diagram.........................................................................................................................17
X4MGeneral Arrangement Drawing.................................................................................................17
X4MActuator....................................................................................................................................18
X4MFiringRate vs. Manifold Pressure.............................................................................................18
-A-

POWER FLAME MODEL X4 BURNERS Rev.10/04
For use byQualified Service Personnel Only
U.S. Patent No. 6,508,645
WARNING: If the information in these
instructions is not followed exactly,a fire or
explosion mayresult causingproperty
damage, personal injury, or death.
Do not store or use gasoline or anyother
flammable liquids in the vicinityof this or
anyother appliance.
WHAT TO DO IFYOU SMELL GAS BURNER SPECIFICATIONS
1. Do not tryto light anyappliance.
2. Do not touch anyelectrical switch; do Input Capacity
BTU/Hr
not use anyphone in your building. X4-400150,000 – 400,000
3. Immediatelycall your gas supplier from X4-700200,000 – 725,000
a neighbor’s phone. Follow the gas X4M-400150,000 – 400,000
supplier’s instructions. X4M-70090,000 –725,000
4. Ifyou cannot reach your gas supplier, Fuel Type Natural or LP Gas
call the fire department. Blast Tube Length 9”, 12”
Inlet Gas Pressure
X4-4005.0 –14” w.c.
X4M-4005.5 –14” w.c.
INSTALLATION AND SERVICE X4-7005.0 –14” w.c.
MUST BE PERFORMED BY A X4M-7005.5 –14” w.c.
QUALIFIED INSTALLER, SERVICE Voltage 120V, 60 Hz
AGENCY, OR THE GAS SUPPLIER AmpRating 5.0 Amp
Motor ¼ Hp,3450 RPM
Transformer 40VA, 24 VAC
1

Rev.10/04
1. GENERAL INFORMATION
The X4 burner is a new generation ofgas power burners designed to fire natural gas andpropaneagainst
a positive furnace pressure.
The burner is a self-contained unit comprised ofa blowerassembly, firing head,ignition system,
combinationgas valve, flame safeguard and control panel. It onlyrequires connectionof115V electrical
supply, minor gas trainpiping, connectionto gas service, and operating controls.
All Power Flame burners are operationallyfire tested at the factory.
2. CAPACITIES & SPECIFICATIONS
Burner NumberX4-400X4-700X4M-400X4M-700
Natural/LP Gas Flowx 1,000BTU/HR150-400200-725150-40090-725
Gas Train Size3/4”1”3/4”1”
Blower Wheel Size6-1/4” x 2-3/4”7” x 3”6-1/4” x 3-3/4”7” x 3”
Blower Motor HP1/41/41/41/4
Voltage120/60 hz120/60 hz120/60 hz120/60 hz
MaximumInlet Pressure to Main Shut-
off CockInches W.C. 14.014.014.014.0
3.ACCEPTANCE PROCEDURE
Open the box and carefullyremove the top cardboard packaging. Lift the burner fromthe box and ensure
all shippedloose items are removed before discarding the box. Checkall parts received against your
computer generated Bill ofMaterial that is enclosed in the owner’s information envelope.
Warranty
The Owners Information envelopepacked with the burner contains a WarrantyRegistration Card. The
WarrantyRegistration Card is also a request formfor a Spare Parts List. An on-hand supplyofspare
parts is highlyrecommended incase ofemergencyshutdown. We request that you complete andreturn
the card toPower Flame in the enclosed self-addressedenvelope as soon as possible.
4.INSTALLATION
Prior to Installation,please review the MART Operator's Manuel for recommend setting
and flue requirements. Additional charts, drawings and
diagrams shipped with the burner are provided in this manual.
Installationmust be in accordance withall local and national codes includingCAN1-B149.1 or B149.2and
Canadian electrical codes for Canadian installations.
2

4.1Ifthe burner is tobe mounted in an existing boiler or furnace, ensure that all fireside surfaces are clean
and in good condition. All doors, cleanouts, cracks or other openings allowing excess air into the
combustion chamber should be tightlysealed, whether the burner is to befired under positive or negative
combustion chamber conditions.
4.2The burner can be mountedthrough a heat exchanger endwall or in the base ofthe boiler – see Figures
1 and 2. The opening for the burner blast tube should not be less than 4 ¼ inches indiameter to allow
easyremoval ofthe burner. The gapbetween the burner opening and the blast tube should be sealed
with non-asbestos, high temperature rope or Ka-O-Wool. Where a newor replacement combustion
chamber lining is to be usedthe chamber is to be built using2300 degree F insulating firebrickor ceramic
fiber blanket.
Figure 1 Mounting in Heat Exchanger
Figure 2 Mounting in Boiler Base
4.3 COMBUSTION CHAMBER SIZING
Table 1 Combustion Chamber Recommended Dimensions
Gas InputWidthLength
MBTU/HRInches Inches
2501317
4501520
6001623
7001725
8501826
4.4 Whichever method ofmountingis chosen, the burner blast tubemust be recessed into the front wall
surface from0” to 1/2”.
3

NOTE:Serious DamageTo The Burner MayResult IfThe Blast
Tube Is Extended Into TheCombustion Chamber.
4.5 Secure the burner to the heat exchanger or boiler, using the burner-mounting flange. The burner-
mounting flange must be secured to the blast tube at the selected location for proper insertion
intotheend or front wall ofthe firedunit. A tight seal between the mounting flange andthefront
plate shouldbe accomplished usingthefactory-furnished gasket or a ceramic or other non-
asbestos fiber rope.
5GAS PIPING
5.1Contact you local gas service companyto ensure that adequate gas serviceis available and to
reviewapplicable installation codes for your area. All gas piping installations must be in
accordance with NFPA 54, National Fuel Gas Code,Definitions and General Field
Recommendations, CGA 3.0, Canadian Natural Gas Installation Code CAN/CGA B149.1 or
Propane Installation Code, CGAB 149.2. This product must be installed onlybya Licensed
Plumber or Gasfitter, when installed in the Commonwealth ofMassachusetts.
5.2Size the main gas line inaccordance with Table2. The figures shownare for straight lengths of
pipe at 0.2” w.c. pressure drop, which is considered normal for low-pressure systems. Note that
fittings such as elbows and tees will add tothepipe pressure drop.
Table 2 - Gas Piping PressureDrop Data
EQUIVALENTLENGTH OF STRAIGHTPIPE IN FEET
203040506080100150200
PipeSize In InchesCFH GAS WITH .2” PRESSURE DROP
3/4”152120105938473665445
1”30025021019018015013511075
1-1/4”520425360325300260230190165
1-1/2”800690560500480410370300260
2”17001400120011001000850750600540
2-1/2”30002500210019001800155013751100950
EQUIVALENTLENGTHS OF STANDARD PIPE IN FEETFOR LISTED FITTINGS
Fitting Type3/411-1/2 1-1/222-1/2Nominal Pipe Size In Inches
Std. Tee2.45.57.59.012.013.5
Std. Elbow4.42.73.74.55.56.1
5.3Refer to Figure 3 for details ofgas piping. (Also refer to anyadditional piping diagrams supplied for this
specific unit.)
5.4Mount leakage test andmain gas cocks, main automatic gas valve or combination gas
valve/pressure regulator, andauxiliaryvalves (ifrequired and not factorymounted) per piping
diagramor Figure 3.
5.5Install pressure regulator (not usedwith combination gas valve/pressure regulator) directly
upstreamofmain automatic gas valve(s) and fit drip leg and main gas cockupstreamofregulator
or automatic valve(s).
5.6 The pilot line should be pipedinto the upstreamtapped nipple to minimizepilot linepiping length.
An optional locationis in a tapping located on the main shut-off cock. Refer to Figure 3. For
ease ofservicing we recommend the use ofa union immediatelyupstreamofthe main gas
pressure regulator or combination gas valve/pressure regulator.
4

5.7 Install ventlines frommain gas regulator (ifused) and diaphragmgas valve where applicable.
Ventlines should be run to the outside ofthebuilding, terminatingclear ofwindows or fresh air
intakes. Outside termination ofventshould have a screen to prevent insects frombuilding nests
in vent pipe.The vent should terminate in a manner, which will preclude the possibilityofwater,
dirt or other foreign matter fromentering the line.
Figure 3 UL GasPiping Train (X4) – See Figure 11B,page 17, for X4M
5.8Test gas lines for leaks using a soap solution. Your local gas service companymaywish to execute or
witness this test.CAUTION – gas pressure above14” w.c. maydamage the standard diaphragmgas
shut-off valve. Do not exceed this valuewhen pressure testing lines unless youcap off line upstreamof
main gas cockand pilot take-off.
5.9 Checkthat sideorifice size is correct according to burner specificationsheet(See Figure 4). To gain
access to orifice, remove Plug A andwithdraw spring and orifice. When reinserting or replacingthe
orifice, ensurethat itseats properlyinside the tee and reinstall plug.
5

Figure 4 Location of Side Orifice
Figure 5 Typical Wiring Diagram for S8680Jwith Proved Pilot Ignition
6

Figure 5ATypical Wiring Diagram for S89F with Direct SparkIgnition
6WIRING
6.1 Refer to wiring diagramshippedwith burner and typicalwiringdiagrams Figures 5 and 5A.The
two power leads (blackand white) are locatedinside theburner panel.
6.2Electrical installation must be made in accordance with the NEC NFPA 70 or Canadian Electrical
Code,Part1 and applicablelocal codes. Ifthis burner is part ofa boiler or furnace package
system, checkwiring diagramas supplied bythe boiler or furnacemanufacturer.
7START UP
7.1Before attempting aburner start up, please review the MART Operator's Manuel for recommend setting
and flue requirements.Also this manual will provide information about theexact sequence of
operation and all other details on the specific PrimarySafetyControl Systembeing used. This
information will be found in bulletins supplied with the burner, as well as technical bulletins covering other
components. All ofthese materials should be usedas reference in burner start up and service.
7.2Checkboiler water level (ifapplicable).
7.3Layoutcombustion test equipment (see Section 8.3).
7.4Attach gas pressure gauge ormanometer to upstreamside ofmain gas cock(0-35” w.c.) andto orifice
pressure tap (0-10” w.c.) as well as to pilot gas pressure test tee tapping (0-10” w.c.).
7.5 Checkthe voltage at the disconnect switch to make certain that it matches that indicated on the burner
label.
7.6Ensure that all dampers in the flue or stackare fullyopen.
7

7.7Install stackthermometer and FlueGas Analyzer sample line into breeching andconnect thedraft gauge
to combustion chamber test point.
7.8Connect a microammeter to the PrimarySafetyControl as directed in the PSG control manufacturer’s
instruction bulletin to determine flame detection systemvalues. The meter is normallyconnectedin
series with the (SENSE) terminal on the S8600or S89F series control.
7.9 With the main and leaktest cocks and pilot cockin OFF position, turn on the gas cockat meter. Checkto
make certain that pressure upstreamofmain and pilot cocks does not exceed 14” w.c. (1/2 PSIG) –
unless special valve traincomponents suitablyratedhavebeen furnished (Refer to Burner Specification
Sheet). Ifpressure is acceptable,proceed tonext step.
7.10 Pilot Ignition
Next check the operation of the gas pilot system.This is a very important part of the start up
procedure.
A. Before attempting burner start up make certain that you are familiar with the operation ofthe
PrimarySafetyControl andother components being used on this specific application. Refer to
Fig. 6and 6A.
B. To prepare the pilot for proper operation, it is essential thatappropriate adjustments be made to
the burner air inlet damper and the pilot gas pressure. SeeTable 3 for the approximate air
damper setting at the various firing rates. Typical pilottest pressures are 3” to 4” w.c. for natural
and propane gas. Normally,lower pressures are required for air damper openings of50% or
less.
Figure 6 Pilot/Gun Assembly– Flame Rod Type – Natural Gas/LP Gas
8

Figure 6ADetail Pilot Assembly
C. Frequentlythe cause for pilot problems relates to gas pressures that aretoo high and/or
air dampersthat are closed too far.Both conditions can cause a fuel rich mixture in the
pilot chamber which can substantiallydelay or totally prevent pilot ignition.
7.11With the leakgas cockclosed and pilot gas cockopen (ifprovided); turn the burner switch ON. The
blower motor will purge the heat exchanger of anyaccumulated combustibles. At the end ofthe purge
cycle, the pilot solenoid valve will energize and sparkwill be initiated. The pilotwill attempt to light for 15
seconds. Adjust the pilot pressure at this time. Ifthe pilot fails to light, power must be removed fromthe
control for 60seconds to allow it to reset. Note:Ifthe leaktest cockis not provided,remove themain
gas valve wire (MV) fromthe control to prevent the main valve fromenergizing during the pilot adjustment
period.
7.12Pilot Adjustment and Main Flame Light Off Procedure
A. Set the air flow(see Table 3)and pilot gas pressure in order to provideinstant pilot ignition, good
flame stabilityand a strong/steadysignal reading. This can beaccomplished as follows: Start
with the pilot pressure at the minimumadjustment on the regulator.When the pilotvalve
energizes beginincreasingthepilotpressure. Notethe pressure where asignal is obtained or
the main valveenergizes. This will be the minimumpilot pressure. Acceptable pilot and/or main
flame current readingis 1 – 5microamp.
B. Raise the pilot gas pressure to the pointwhere the signal and/or main valve drops out notingthis
pressure. Reduce the pressure slightlyandrecycle the burner for an attempt to relight the pilot at
this pressure. Ifrelight occurs this is the upper limit ofthe pilot pressure. Now set thepilot
pressure betweentheminimumand maximumpressure. This range is typically1” w.c..
C. After attaining the proper pilotflame signal values, cyclethepilotoff and onseveral times in order
to ensurereliability(with the gas leaktest cockstill closed). Turn BurnerSwitch Off.
D. Havingestablished pilot reliability, open gas leaktest cock.
E. After burner has completed pre-purge and established a good pilot flame signal reading, the main
automatic fuel valve will be energized. The main flame should light immediately. Iflight off does
not occur, it is possible that air will needto be purged fromthe main gas line. Adjust main gas
pressure regulator (ifused) or combination valve regulator to obtain the desiredfiring rate
pressure.
F. Adjust burner as necessaryto provide smooth ignition ofmain flame. Ifpilot flame signal drops
significantlywhen main fuel valve opens, increase pilot gas pressure slightlyto obtaina
reasonablystable flame signal value. 9

G. Select and install the main orifice thatcorresponds to the desiredfiring rate. Make certain that
the airflowsetting provides the correct CO2or O2levels and other combustion values at the
proper firing input rates.
See Section8 and Table 3 for firingrate information. Generallyaccepted values for natural gas
are 8½ to 10% CO2or 5½ to 3% O2. Equivalent CO2readings on propane gas are 10 to 11½%
CO2or 5½ to 3½% O2.It is important that the CO (carbon monoxide) level is checked and held at
0% or minimum(typicallyunder 100ppmor .01%). Checkwith local utilityand anyother
authorities having jurisdiction before making final burner adjustments.
7.13 Direct Spark Ignition
A. Before attempting burner start up make certain that you are familiar with the operation of
the PrimarySafetyControl andother components beingused on this specific application.
Refer to Figure 6b to verifythe correct position ofthe ignition electrode placement since
shipment mayhave altered the placement.
B. Set the burner’s combustion air inletdamper to the approximate settingas shown inthis
manual for the desired firing rate. Also, verifythat the correct main orifice is installedin
the main orifice tee.
C. Open the main manual gas valveand turnthecombination gas valve to ON. Turn the
burner power on. The blower motor will purge the heatexchanger ofanyaccumulated
combustibles. At the end ofthepurge cycle, typically35seconds, the combination valve
will be energized and asparkwill be initiated. The trial for ignitionwill beapproximately
three seconds.
D. Complete setup in accordancewith item(G) above.
E. Ifignition failure occurs the main power must be switched off for at least one minute to
allowthe control to reset.Refer to the Service/Maintenance section for further
information on Direct SparkIgnition.
Figure 6BDetailDirect Spark Gun Assembly
Conduct all applicabletest procedures shownin control manufacturer’s bulletins included with burners. Set and
checkoperationoflowandhigh gas pressure switches (ifapplicable), all burner andheat exchanger controls, and
10

Rev.9/05
operating devices. Checkblower airflowswitch byfirst closingmain gas cockand disconnecting motor
leadwire. A properlyadjusted air switch should open within 3 to 4 seconds when the power is removed
fromthe motor.
7.15Clean up area around the burner andinstruct owner and/or operator.
7.16 Post Operating Instructions card (inside backcover) close totheburner inclearlyvisible position.
8.COMBUSTION ARRANGEMENT REQUIREMENTS
8.1The X4 burner has been designed to fire with high combustion efficiencyintocombustion chambers with
positive, balanced or negative pressures using natural orLP gas only.
8.2 In order to fire efficiently,theburner requires an adequatesupplyofcombustion air. Ventilation to any
enclosed area should be provided on the basis of½ square inch ofopening for each 1000 BTU/HR input.
This excludes the requirement for anyother fired equipment in the area. The enclosed area should not
become excessivelyhot and under no circumstances should beunder a negative pressure.
The burner shouldbe initially set up and servicedat regular intervals (preferablyat the beginning ofand
mid waythroughhigh use periods) bya trained serviceman using the proper test instruments. Failure to
maintain the correct burner settings mayresult in inefficient gas consumption,premature wear ofburner
components or explosion hazard.
8.3 Approximate gas flows and pressures are showninTable 3for natural gas and LP gas. Actual firing
rates should be verified byclocking the gas meter and applying the appropriatecorrectionfactor.
Table 3
Natural/LP Gas Orifice Pressure Settings/FlowRate. NOTE: Pressure taken at Combination Valve Pressure
Tap Upstream of Orifice.
X4-400MainMBH Natural GasMBH LP GasApprox. Damper Position
Orifice1000 BTU/CF2500 BTU/CF
Diameter/I.D.#2"3"4"2"3"4"MBHIndicator #
.203 11331801981501
.234 21581962272002
.265 31501832102132502873003
.281 41752152482192642924004
.343 5200245280298351389
.406 6225274316370431Note: Pilot pressure is different
.468 7275338390410at eachdamper position and
.500 8295360415must be set at eachposition.
None400
X4-700 MainMBH Natural GasMBH LP GasApprox. Damper Position
1000 BTU/CF2500 BTU/CFOrifice
Diameter/I.D.# 2"3"4"2"3"4"MBHIndicator #
.203 11742012001
.234 21621982393001 3/4
.265 31201481711942272724002
.281 41311631892012502855003
.343 51862302692733353876004
.406 62463023943834705417006
.468 73063724334725786677259
.500 8326394454497609725Note: Pilot pressure is different
None451563652At each damper position and
725 @4.8"Must be set at eachposition.
11

8.4The correct test instruments are:
a.O
2
analyzer (electronic or Fyrite absorption system)
b.CO indicator (Monoxor or similar)
c.Stackthermometer
d.Draft gaugeor inclined manometer
e.U-tube manometer or calibrated 0-10” and0-35” w.c.pressure gauge
f.Combination volt/ammeter
g.D.C. Micro-Ammeter
9.SERVICE/MAINTENANCE SUGGESTIONS
9.1 Burner Fails to start:
1.Bad fuse or switch openon in-coming power source,or motor overload out.
2.Control circuithas an opencontrol such as operating, limit or lowwater cut-off.
3. Push the resetbutton on the motor or open the power circuit to the primarysafetycontrol.
4. Loose or faultywiring. Tighten all terminal screws. Checkwiring, against wiring diagram
furnished with burner.
9.2Burner Motor Runs, but PilotDoes Not Light
1. Be sure gas is turned onat meter and pilotcockis open.
2. Placehand on pilot valve to “feel” it open. Checkgauge at tee in pilot line for gas pressure and
prompt opening ofpilot valve.
3. Checkvisuallyor bysound for sparkarcing.
4. Refer to section 7.10 on pilot checking procedures.
5. Checkair switch and be sure its circuit closes during start.
9.3Burner Motor Runs, PilotLights, but Main Gas Valve Does Not Open
1. Checkflame signal. Ifsignal is low,adjust pilot gas pressure and air settings for improved readings.
2. Checkgas valvecircuit.
3. Shut-off cockor test cocknot open.
4. Defectivemain valve.
9.4Occasional Lockouts For No Apparent Reason
1. Re-checkmicoamp readings. Ifinsufficient, checkgas pressure and air damper setting. Check
electrode setting. Ifflame signal is low, flame rod mayhave to bere-positioned.
2. Checkignitioncable and electrode porcelainfor damage or breaks, which couldcause short.
3. Checkfor loose or broken wires.
9.5Burner Will NotStart – Even Though Burner Had Never Failed Before Or Had Been running On Normal
Cycling Without Failure.
1. Operating Control circuit open.
2. Defectivecontrol or loose wiring.
3. Limit circuit open.
9.6 The burner must be periodicallyinspected to insure safetyand performance. All maintenance must be
performed with the main electrical power off and the main gas shutoff valve off.
1. Inspect blower inletscreen and clean anybuildup oflint.
2. Inspect blower wheel blades and clean anybuildup ofdirt.
3. Inspect ignition electrodes andwiring for anycracks that maycause shorting.
4. Oil the blower motor at themanufacturer’s recommended intervals.
5. Verifythat the pilot andor direct sparkelectrodes are still within specifications (set per drawing 6,6A
and 6B in this manual).
6. Verifythe proper operation ofthePrimarySafetyControl, airflowswitch, and operating controls.
7. Checksafetygas shutoff valves for gas tightness.
12

9.7In the event ofextended shutdown, themain power should be turned off and themain manual gas shutoff
valve should be closed.
9.6 EMERGENCY SHUTDOWN: WARNING: Should over-heating occur: (1) shut off the manual gas valve
to the appliance, (2) donotshut off the control switch to the feed water pump or blower.
An additional source ofinformation relative to trouble shooting canbe found in the Flame Safeguard
Control Manual suppliedwith the burner.
10. BURNER PARTS LIST – X4 and X4M
1. Burner Housing16.Gun Head31.Outer Damper
2. Side Orifice Tee17.Side Orifice tee32.Air Sensing Tube
3. Side Orifice Spring18.Side Orifice Spring33.Orifice Kit
4. Gun Assembly19.Pilot Regulator34.Direct SparkTransformer
5. Flange Gasket20.Pilot Solenoid Valve35.Gas Piping Support Bracket
6. Mounting Flange21.Combination Gas Valve36.Damper Axle
7. Blower Wheel22.Main Gas Cock37.Relay
8. Motor Plate23.Pilot Gas Cock38.5/16” Ball Joint Swivel
9. Blower Motor24.Pilot Tubing39.Mod Motor
10. Air Switch25.Pilot Assembly40.ButterflyValve
11. 24 VoltTransformer26.Ignition Electrode41.5/16” Linkage Rod
12. Panel & Door27.Flame Rod42.Light
13. Flame Monitor28.BackPlate43.Axle Bushing
14. Grounding Lug29.Inner Damper44.1/2” Damper Arm
15. NippleTapped30.Middle Damper45.PieDPR Retainer Washers
X4
13

X4M
14

15

11. SEQUENCE OF OPERATION FOR X4M BURNER
11.1 Refer to typicalwiring diagramfor X4M burner (Figure 11A).Upon acall for heat, the blower motor
starts, closingthecombustion air switch.Power is supplied to the 24-vac transformer. Initiallypower
to the actuator is held out through one set ofnormallyopencontacts on the 24-vac relay.
11.2 Sincepower is not supplied to the actuator it will springreturn clockwise to the open damper position
ifnot alreadythere.When the actuator reaches thefull clockwise position (full open damper) the
internal auxiliaryendswitch closes (S1 to S3).
11.3 24-vac power will be supplied throughtheS1 – S3 contacts and the combustion air switch to the
S8680 control.
11.4 The control will begin its pre-purge time period ofapproximately30 seconds.
11.5 At the end ofthe pre-purge period, a trial for ignitionwill beattempted. On pilot ignited burners the
pilot pressure would be sethere to achievethebest pilot performance. Refer to Pilot Adjustment
Procedure earlier in section 7.10 ofthis manual.
11.6 When the main gas valve is energized,after a proven pilot or during direct sparkignition on DSI
burners the 24-vac relaywill also beenergized.
11.7 One set ofnormallyopen relaycontacts close whichinterlocks the high fire auxiliaryend switch.
Another set ofrelaycontacts closes and completes the modulation circuit.
11.8 Modulation oftheburner is nowaccomplished bythe control signal. Depending onthesetting ofthe
Direction Control Switch located on the actuator (Figure 11C),a lowor high input signal candrive the
actuator clockwise or counterclockwise (lowfire or high fire).
11.9 An adjustable stop located ontheactuator (Figure 11C), canbe used to limit the high fire or lowfire
position.Ifthe high fire damper position is changed due to alower than maximumfiring rate, the pilot
should berechecked at this new damper position.
16

Figure 11A- Typical Wiring Diagram For X4M
Figure 11B – General Arrangement Diagram for X4M
17