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RV Furnaces. Factory Information. 676 Broadway Dayton, Tennessee 37321 Website: www.rvcomfort.com E-mail address: smcsales@suburbanmfg.com. Factory Support Phone Numbers. Phone: 423 775-2131 Fax: 423 775-7015 Business Hours: 8 AM to 5 PM Eastern Time.
Transcript
RVFurnacesFactory Information
  • 676 Broadway
  • Dayton, Tennessee 37321Website: www.rvcomfort.comE-mail address: smcsales@suburbanmfg.comFactory Support Phone NumbersPhone: 423 775-2131 Fax: 423 775-7015Business Hours: 8 AM to 5 PM Eastern TimeFactory Technical Service Extension 7102
  • Service Manager
  • Ronnie Ellison ext. 7007
  • Assistant Service Manager
  • Louie Richard ext. 7005
  • Factory Customer Service Extension 7101
  • Customer Service Manager
  • Sheila Cheek ext. 7016
  • Customer Service
  • Vicki May ext. 6372
  • Linda Welch ext. 6373
  • Jennifer Yawn ext. 6371
  • Furnace ModelIdentificationNT Lightweight Series Furnace
  • NT16/20 SQ
  • Side duct discharge.
  • NT Series Furnace
  • NT16/20 SEQ
  • Direct discharge
  • NT Heavyweight Series Furnace
  • NT30/34SP NT40
  • Side and bottom
  • duct discharge.Park Model Furnaces(120 VAC)
  • P40
  • Side and bottom duct discharge.
  • Can be field converted to natural gas.
  • Same dimensions as NT series furnace
  • SF Series FurnacesRear & Front Gas
  • SF 20/25/30/35/42Q
  • Rear gas connection
  • Service through outside door application.
  • Front, bottom, top & side duct discharge.
  • SF20/25/30/35/42FQ
  • Front gas connection
  • Service from inside coach.
  • Front, bottom, top & side duct discharge.
  • Vertical Mount Furnaces
  • SFV 20/25/30/35/42Q
  • Rear gas connection
  • Service through outside door application.
  • Front, bottom, top & side duct discharge.
  • SFV 20/25/30/35/42FQ
  • Front gas connection
  • Service from inside coach.
  • Front, bottom, top & side duct discharge.
  • SH Series Furnace
  • SH35/42 SH35/42 F
  • Front & Rear gas connection.
  • Front, bottom, top & side duct discharge.
  • 9 ¼ inches H x 17 W inches x 20 inches D
  • SHD-2542 Furnace
  • Dual Rate 25,000 & 42,000 BTU
  • Front, bottom, top & side duct discharge
  • Tools & Equipment RequiredEquipment
  • Volt-Ohm Meter
  • Manometer (calibrate monthly with U-tube)
  • Leak Check Solution
  • Assorted Hand Tools
  • Fenwal Module Board Tester---Part # 641511Furnace RequirementsGas Pressure
  • 11 inches W.C. Minimum
  • 14 inches W.C. Maximum
  • W.C. water column
  • Test with at least half of the appliances operating.
  • Voltage
  • 10.5 Volts DC minimum
  • 13.5 Volts DC maximum
  • Pressure Drop Test
  • Install pressure gauge into gas system
  • Use leak check solution on fitting
  • Eight (8) inches W.C. for three (3) minutes
  • Furnace ComponentsWire Connections
  • Four wires are used for connections.
  • Red 12 VDC positive.
  • Yellow 12 VDC negative.
  • Blue thermostat positive +.
  • Blue thermostat return voltage.
  • Thermostat
  • Bi-metal thermostat shown.
  • Device used to control operation of furnace by reacting to ambient temperature.
  • On/Off Switch
  • Device used to control power to the module board.
  • Rewire kits available to update non fan control MB furnace to fan control MB.Backwards compatibility with 520741 non fan control module board.Fan Control Module Board Information Fan Control Module Board Update On model SF20Q starting serial number 133900000 a smaller dimension fan control module board was introduced.Has the same operation as a 520820Limit Switch
  • Device used as a safety overheat switch. Normally closed switch.
  • NOTE: sail switch may be before limit switch in some models.
  • Sail Switch
  • Safety device that proves air flow.
  • Normally open switch.
  • Furnace Motor
  • Double shafted provides both room and combustion air.
  • 12VDC motor. Built-in thermal overload protection.Gas Valve
  • Controls and regulates gas flow to appliance
  • Furnace Orifice
  • Meters gas flow.
  • Drill size matches to BTU rate of furnace.
  • Furnace Burners
  • A fuel burning device that supports combustion.
  • RibbonPunch PortTubeElectrodes
  • Conductor of ignition source.
  • Local or remote flame rectification.
  • RemoteLocalSparkFlame senseGround1/8 inch spark gapSF Electrode & Wire Assembly
  • Local flame sense.
  • 1/8 inch spark gap between burnerFurnace Sequence of Operation
  • Understanding the sequence of operation makes diagnosis quick and accurate.
  • Sequence of Operation
  • Thermostat calls for heat.
  • Contacts close.
  • Sequence of Operation
  • Current flows through the ON/OFF switch
  • Voltage in from thermostat. Blue wireVoltage out to module boardPower terminal. Blue wireWire Connections to Fan Control Module BoardRed power & blue thermostat wireSequence of Operation
  • Power to module board
  • Checks for proper voltage
  • Power to sail switch/limit switch circuit
  • Sequence of Operation
  • Checks sail switch circuit
  • If circuit completed motor will not start
  • Sail switch is closed or bypassed
  • Relay will have a buzzing sound
  • Sequence of Operation
  • Module board checks for power to return from sail switch/limit switch circuit proving sufficient air flow to support combustion
  • If no power returns blower shuts off in 30 seconds
  • Wire Connections to Fan Control Module BoardBlue return wire from limit or sail switchSequence of Operation
  • Power to module board terminal within 15 seconds
  • Motor will start
  • Red wire connects to blower output on module boardBlack wire to ground terminal blockWire Connections to Fan Control Module BoardRed power & blue thermostat wireRed wire voltage out to motorYellow ground wireSequence of Operation
  • If power returns from sail switch/limit switch circuit
  • 10-15 second purge cycle
  • Sequence of Operation
  • Power through sail switch/limit switch circuit
  • Wire Connections to Fan Control Module BoardRed power & blue thermostat wireRed wire voltage out to motorRed wire Voltage in from Limit or Sail switchBlue return wire from limit or sail switchYellow ground wireSequence of Operation
  • Module board simultaneously:
  • Provides spark to electrode
  • Provides voltage to gas valve
  • Checks for flamerectification
  • Yellow wire to ground terminal blockSequence of Operation
  • If flame is detected
  • Shuts off spark to electrode
  • Keeps gas valve powered
  • Monitors flame
  • Sequence of Operation
  • If flame is not detected after 7 second trial for ignition period
  • Shuts off ignition
  • Goes through purge cycle
  • 2nd trial for ignition
  • Goes through purge cycle
  • 3rd trial for ignition
  • Sequence of Operation
  • If flame is not detected after 3 TFI
  • Lockout occurs
  • Blower shuts off after 3 minutes
  • Thermostat must be manually reset
  • Furnace Troubleshooting
  • Understand the complaint.
  • When does the issue occur?
  • Hot or cold outside ambient?
  • Start of cycle or mid-cycle?
  • Always turn off gas supply when checking initial sequence of operation!
  • AMP DRAW TESTRed motor lead is removed from module board motor terminal.MOTOR AMPERAGE CHART Gas Valve Troubleshooting
  • Gas pressure regulator 10.5 inches output
  • Redundant protection
  • 30-50Ohms on each solenoid.48 AmpsGas Test PortSF burner with electrode settingTroubleshooting Module Board
  • It is recommended to use the module board tester.
  • The module board will monitor the sail switch circuit upon a call for heat if the sail switch is closed the motor will not operate.
  • Plastic combustion air housing (SF models)Sail switch mounted to Plastic room air housing. If closed no motor operation.Troubleshooting Module Board
  • If the sail switch does not close or the limit switch is open the furnace will shut down blower operation with no TFI (trial for ignition) within 30 seconds.
  • Troubleshooting Module Board
  • If during the heating cycle, the limit switch circuit opens and remains open for five (5) minutes, the module board will go into LOCKOUT and shut down blower operation.
  • Module board constantly checks for a minimum of 9.5 VDC. If not available the module board will go into STANDBY mode until voltage is available.
  • Check burner for proper flame. Flame should be blue and have definitionGas pressureRestriction in combustion chamberTroubleshooting Tips Installation Troubleshooting
  • Always start by reviewing the installation.
  • Installation issues can cause operation issues with the furnace.
  • Check furnace for proper mounting and furnace is secured properly.Check all gas connections with leak check solution.Installation TroubleshootingInstallation Troubleshooting
  • Check furnace venting
  • Vents not blocked
  • Vent tubes have proper overlap
  • Check for soot on vent. If soot is present check the following
  • Check combustion chamber integrity
  • Check all gaskets
  • Installation requirements of vent cap & intake tube
  • ½” minimum overlap on intake tube
  • 1 ¼” minimum overlap on exhaust
  • Refer to Installation Manual for correct intake tubeSF vent cap
  • Silicone seal around perimeter of vent cap
  • NT vent cap Silicone seal around perimeterVent screw securedFurnace Installation Checks
  • Return Air
  • Ducting
  • Clearances to Combustibles
  • Refer to the furnace installation manual for each furnace model’s requirements.
  • Return Air Installation Checks
  • Verify return air of minimum of 55 sq. inches.
  • Total free unobstructed return air to the furnace.
  • Measure opening and reduce square inches by restriction percentage of grille.
  • Insufficient return air will cause the furnace to overheat and cycle on limit.
  • Return Air review
  • The following pictures provide information on return air configurations.
  • Installation Checks Return airMeasure open area of grille.Furnace cannot receive return air when door is closed.Ducting Installation Checks
  • Refer to the Installation manual for the minimum ducted square inches for each model.
  • Verify duct connections are tight on the furnace.
  • Ducts terminating in a dead air space with no means for return air can not be counted in the required duct area.
  • Ducting
  • In RV manufacturing several styles of duct work are used.
  • In-floor, side discharge using flex hose.
  • The following illustrations will show different configurations.
  • Installation Checks Ducting
  • Avoid making sharp turns in the duct system. Each 90 degree adds 10 feet of hose.
  • Vertical installation. Ducts are mashed and restricted.2” Duct
  • Ducts 2 inches in diameter or smaller can not be counted in the required duct area.
  • Duct pulled tight not collapsedDuct pulled tight & not collapsedExcess hose inside cabinetReturn air grille minimum 18” from heat ductPlumbing and Electrical Components Can Crush DuctDuct crushed by plumbingDuct pinched as it passes through floorBottom Duct Installation
  • Verify unit is installed properly over cut out in floor. Correct if necessary.
  • Use gasket to seal between unit and floor.
  • NT knock out dimension 3 ¼ inches x10 inches.
  • SF knock out dimension 4 inches x 14 inches.In-floor PlenumMaintain minimum open duct area throughout entire duct system including registerDuct extending into plenum too farFloor RegisterRug or obstruction over floor register can cause limit to cycle.Closeable register not recommendedInstallation Clearances
  • Verify installation of furnace per installation manual.
  • Check and verify the following before installation.
  • These instructions pertain to installing a new or replacement furnace.
  • Clearances to Combustibles
  • Maintain and adhere to minimum clearances from the furnace cabinet to combustibles per the furnace installation manual for each furnace.
  • Location
  • Select a location out of the way of wires, pipes, that may interfere with installation.
  • Clearance Required Opening
  • An opening must be provided in the interior of the cabinetry directly in front of the furnace.
  • Clearance Furnace Removal
  • The opening must allow for free, unobstructed removal of the furnace.
  • Serial Number informationSerial number information.00020449D00= year 200002= 2ND week04449D serial with a deviation listedWhen Submitting a Warranty Claim
  • Serial Data Plate
  • Model number
  • Serial number
  • Date of purchase
  • Include this information on warranty claims
  • Suburban Furnace Warranty
  • Two years parts and labor limited warranty.
  • 3rd through 5th year limited warranty on the heat exchanger (no labor).
  • Flat rate time allowance at shop rate.
  • One year limited warranty on all replacement module boards
  • Suburban Furnace Warranty
  • Parts that need to be returned with warranty claim
  • Module boards, motors, gas valves, combustion chambers.
  • Warranty parts will have a UPS return tag when shipped from Suburban. This will cover return freight cost.
  • Warranty Information
  • Always use GENUINE Suburban factory authorized parts.
  • Do not need to be recommended service agency to perform warranty work.
  • After Market Bug ScreensNot recommendedDo not install SCREENSover the vent for any reason.
  • Screens will become restricted,
  • and can cause unsafe furnace operation.Furnace Information
  • We have just discussed furnaces please remember that when the appliance is installed into a RV it becomes a heating system.
  • Not just a furnace.Questions?
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