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September 2003

INTRODUCTION

The 2004 edition of the Atwood Furnace Service Manual is a resource created to help
service technicians identify Atwood product by serial number, diagnose service
problems and efficiently and effectively process warranty claims.

Changes to the Hydro Flame furnaces include:

• Ignition boards in the 79, 85 and 89 series furnaces now have the blower relay

incorporated into the PC board. These boards are compatible with previous Hydro
Flame furnaces. There is no longer a remote relay.

• New boards have a diagnostic ability with 4 fault codes.

• Furnaces with no outside access doors (only an exhaust vent) became available in

2003; the initials L/D in the model number identify these models. The gas valve was
re-oriented with a longer inlet manifold to make this possible.

Each of the manuals within this series offers a general overview of the product as well
as more specific product information. For each product within the manual, you will find
model identification, recommended tools and equipment, a sequence of operation,
warnings, annual maintenance procedures, parts and troubleshooting guides, warranty
procedures, flat rate schedules, and replacement part reference charts.

Due to the rapidly changing personal computer revolution we have placed
troubleshooting information in a variety of places to make sure that the most accurate
information is available. The best place to find the current information about Atwood
products is our website: www.atwoodmobile.com. At our website brochures may be
downloaded, trouble shooting guides reviewed and the latest information bulletins can
be read. In addition all Atwood Authorized Service Centers are listed on our site,
accessible via an easy-to-use search system.

Service for all Atwood products is handled out of our Rockford location. Should you
have any questions regarding our products or the information contained in this manual
simply dial 1-800-825-4328. 

Be sure to have the Model and Serial Number when you call.

Atwood Service Department

Disclaimer:  The data presented in this publication is obtained from the most reliable sources, and is believed to be accurate as of the date of publication.
Responsibility for typographical errors or omission of data cannot be assumed by the publishers.

Summary of Contents for 1522 2-STAGE & R-25

Page 1: ...of operation warnings annual maintenance procedures parts and troubleshooting guides warranty procedures flat rate schedules and replacement part reference charts Due to the rapidly changing personal...

Page 2: ...boards Air Speed Indicator P N 34207 This hand held device will let you determine air flow out of a heat register It will help you isolate restricted ducting Incline Manometer P N 34208 This meter mea...

Page 3: ...noid Gas Valve 25 Burner Head Electrode Valve Assembly 25 The 4 Always Gas Pressure Voltage Ducting Return Air 26 27 Trouble Shooting Guides Thermostat 29 Electronic Ignition Models 30 31 Pilot Model...

Page 4: ...MINIMUM DUCTING CONFIGURATION 7912 II 7916 II 7920 II SIDE DISCHARGE UNITS Provides the most air flow and heat to remote heat outlets The duct runs need to be as short and straight as possible for opt...

Page 5: ...ox Retain to fasten the Air Box Insert to the bottom of the air box 4 Install the Air Box Insert into the air box paying particular attention to the direction where you would like the warm air diverte...

Page 6: ...vertically the exhaust port must be located at the bottom Extra care must also be given in sealing this type of installation Consult the installation manual for details Heat Outlets This furnace can b...

Page 7: ...ed to a hard duct system soft ducted out the back to a discharge plate into a hard duct system or completely soft ducted from a combination of the six outlets located on both sides and back of the fur...

Page 8: ...valve is not used when a combination circuit breaker and ON OFF switch is used Black Red Blue Black White Red PWR BLO Black Red Black High Tension White White Red 12V DC NEG Red 5179 Yellow White GRO...

Page 9: ...ED FAN GRY GRIS BLK NOIR GRN VERT GRN VERT GRN 115 VAC LINE C ble 115 VCA 115 VAC NEUTRAL 115 VCA NEUTRE 115 VAC GROUND 115 VCA TERRE 1 2 3 1 2 3 4 5 6 1 2 3 4 5 6 7 8 9 BLACK NOIR WHT BLANC GRY GRIS...

Page 10: ...SAIL SWITCH WHITE LIMIT SWITCH WHITE BLUE BLUE GROUND BLUE THERMOSTAT 12v LS SS TH CB ICB Pwr Blw TH GND Ground GV Gas Valve HV High Voltage EL Electrode MOT Blower Motor SS Sail Switch 12v GND FS HV...

Page 11: ...1 2 2 3 3 4 4 5 5 6 6 12 VDC yellow thermo blue thermo blue sail switch circuit breaker motor limit switch relay ground 85 II sail switch circuit breaker relay motor limit switch power valve sensor va...

Page 12: ...E THERMO BLUE GROUND THERMOSTAT OFF ON BLUE GREEN GREEN BLACK BLACK BLACK 1 1 2 2 3 3 YELLOW WHITE BLACK WHITE THERMO BLUE WHITE WHITE BROWN AC CAPACITOR MOTOR RUN 120 VAC GREEN 120 VAC BLACK 120 VAC...

Page 13: ...hite Black White Blue Blue Blue LS SS PS MOT C B Orange Main Valve GV Redundant Valve 3 2 1 2 3 4 56 Case Bulk head CB Circuit Breaker GND Ground GV Gas Valve HV High Voltage EL Electrode MOT Blower M...

Page 14: ...N DESIGNED TO OPERATE STANDARD AIR CONDITIONING UNITS IN CONJUNCTION WITH A RV FURNACE COOL FAN OFF HEAT M Display System Switch Temperature Set Mode Set 7 5 VDC ANALOG A C SYSTEMS DOMETIC THERMOSTAT...

Page 15: ...set point LO Air conditioner compressor and low speed fan operate to satisfy set point HF Air conditioner fan runs at high speed to circulate air Furnace fan does not run LF Air conditioner fan runs a...

Page 16: ...A timing circuit allows the blower to purge the chamber 15 17 seconds 2 The board supplies current to the gas valve and causes it to open 3 As the valve opens the board sends a high voltage spark to t...

Page 17: ...activates the open limit switch diagnostics and makes the LED on the controller module to flash and shuts down the gas valve See chart As power is applied to the circuit board the system does the fol...

Page 18: ...the system as a safety to prove there is adequate air for combustion The limit switch is an in line safety device which protects the furnace from any over heating conditions The contacts in the limit...

Page 19: ...board supplies current to the gas valve and causes it to open There is an electrical switch in line to the valve to allow power to be manually shut off to the valve This switch must be on for the fur...

Page 20: ...blocked by snow Locate the furnace in an area where the flue gases will not cause building materials to degrade over time Install furnace so electrical components are protected from water Do not use...

Page 21: ...RTMENT Clean the control compartment to remove dirt and lint DUCTING The heat ducts should be clean and clear of obstructions Check for proper duct connection Any ducts disconnected from the furnace o...

Page 22: ...d in conjunction with air conditioners and our furnace The warranty installation instructions and diagnostic information is provided by the manufacturer of the thermostat However if you need to isolat...

Page 23: ...requires a specific motor RPM in order for proper ignition and combustion to take place Since it is very important that the proper motor be used for a specific model of furnace you must identify if y...

Page 24: ...ch is an air proving device It is a safety component that will not let ignition occur until it sees 75 of the motor s rpm s It insures that the combustion wheel is rotating fast enough so that there i...

Page 25: ...The different models and or BTU ranges of furnaces use different burner heads These burners differ by the size of the top gas port holes or the deflector that runs through the throat of the burner If...

Page 26: ...ns 4 RETURN AIR The return air passage should meet the minimum square inches as specified for the particular model of furnace in the installation instructions This air passage should also be clean and...

Page 27: ...r gaps if furnace is installed in middle of run the main duct run must be a minimum of 24 sq inches if furnace is installed at the end of the run the main duct must be 48 sq inches 4 Return Air This r...

Page 28: ...28 NOTES NOTES THIS PAGE INTENTIONALLY LEFT BLANK...

Page 29: ...Replace relay and thermostat Covered under warranty No continuity through thermostat with contacts closed and switch on Replace thermostat Continuity through thermostat with contacts closed and switch...

Page 30: ...Correct polarity Motor running slow Check voltage first If 12 VDC while running replace motor Exhaust blocked Clean exhaust Combustion air wheel loose Reposition and tighten Sail switch defective or w...

Page 31: ...sters must be fully open and unrestricted Furnace over fired Set gas pressure to a minimum of 11 W C with all appliances running replace regulator if not obtainable Also check main burner orifice it m...

Page 32: ...pending on problem encountered Gas pressure incorrect Set pressure to a minimum of 11 W C with all appliances running Replace regulator if not obtainable Limit switch defective or wire off Reconnect w...

Page 33: ...aled Seal vent where it meets with the furnace MICA window missing Replace MICA Combustion air hose plugged or collapsed Replace combustion hose Water in propane Add alcohol to the propane bottles Bur...

Page 34: ...or to signal the circuit board the flame is established Terminology Definition Fan Switch A normally open switch that closes at a set temperature allowing power flow to the motor and allows the motor...

Page 35: ...o the Gas Valve Sail Switch Air prover switch that will engage when the Blower Motor reaches 75 of the rated RPM Secondary Air Combustion Air that helps complete the combustion after the Burner is on...

Page 36: ...a more difficult and lengthy process delaying payment of your claims Together we can maintain a speedy and efficient warranty program WATER HEATERS HARDWARE jacks couplers 5th wheel braking systems At...

Page 37: ...or damage to personal property or revenues Some states do not allow the exclusion or limitation of incidental or consequential damages so the above limitations or exclusions may not apply to you 9 Any...

Page 38: ...t 70 70 70 70 70 Electrode 60 60 60 70 70 Exhaust Tube 70 70 Gasket Comb Chamber 1 50 1 50 1 50 Gasket Electrode 60 60 60 70 70 High Tension Lead 50 50 50 50 50 Limit Switch 90 90 90 60 60 Manifold In...

Page 39: ...ion Wheel 14 Duct Adapter 15 Duct Cover Plate 16 Air Hose 17 Thermostat SPECIFY COLOR 18 Limit Switch L 170 19 Relay 20 On Off Circuit Breaker 21 Burner Head 22 Manifold 23 Motor Gasket Item Descripti...

Page 40: ...2 Duct Adapters 23 Duct Cover Plate Drawing Description of Parts 8516 8520 8525 8531 8535 24 Electrode 25 Electrode Gasket 26 Flex Adapter Plate Asmbly 27 Gas Inlet Plug 28 High Tension Lead 30 Bottom...

Page 41: ...20 Electronic Ignition Board 22 Duct Adapters 23 Duct Cover Plate 24 Electrode 26 Flex Adapter Plate Assembly Kit 27 Gas Inlet Plug 28 High Tension Lead 30 Top Bottom Side Cover 32 Limit Switch 35 Mo...

Page 42: ...Specity Model 20 Electronic Ignition Board 22 Duct Adapters 23 Duct Cover Plate 24 Electrode 26 Flex Adapter Plate Assembly Kit 28 High Tension Lead Cover 30 Top Bottom Side Plate 32 Limit Switch 35...

Page 43: ...ide Plate 13 Electronic Ignition Board DC Kit 14 Recessed Pan MUST ORDER BY COLOR 16 Valve AC 17 Motor DC 18 Sail Switch 19 Draft Cap Assembly DC AC35 20 Circuit Breaker DC 23 Junction Box Asmbly AC 2...

Page 44: ...Assembly 20 Electronic Ignition Board 22 Duct Adapters 23 Duct Cover Plate 24 Electrode 26 Flex Adapter Plate Assembly Kit 27 Gas Inlet Plug Seal 28 High Tension Lead 30 Top Bottom Side Cover Plate 32...

Page 45: ...Valve 19 Vent Assembly 20 Electronic Ignition Board 22 Duct Adapters 23 Duct Cover Plate 24 Electrode 26 Adapter Plate Assembly 28 High Tension Lead 32 Limit Switch 35 Motor Gasket 36 Motor 37 Orific...

Page 46: ...51 7 AMP with door 33752 10 AMP with door 34034 15 AMP with door 34011 7 AMP without door circuit breaker on off 34012 10 AMP without door circuit breaker on off 34013 15 AMP without door circuit brea...

Page 47: ...Motor PF 26170Q 38554 Motor PF 23211Q 37646 Motor Clamp 37602 Motor Lock Bracket 37603 Motor Lock Bracket 37604 Motor Lock Bracket 37801 Motor Mounting Wall Kit Relay 31017 Klixon Relay Thermostats 38...

Page 48: ...stage R 25 Miscellaneous 37844 Air Intake Tube No Longer Available 32882 Door Screen 31474 Duct Adapter 4 36688 Duct Adapter 2 31361 Duct Cover Plate 37410 Gas Inlet Plug 37411 Slide Plate 38248 Trans...

Page 49: ...000 BTU 31280 52 31 000 BTU 32285 51 35 000 BTU 34004 49 40 000 BTU 34092 30 40 000 BTU NAT 34093 32 35 000 BTU NAT Circuit Board 37966 Controller Module 37984 Controller Module Bracket 37515 Ignition...

Page 50: ...ngle sense 36998 Electrode dual sense 36999 Electrode dual sense 36997 Electrode dual sense 37079 Electrode Cover Plate Single Sense 36044 Electrode Cover Plate Dual Sense Gaskets 35890 Burner Plate G...

Page 51: ...37716 NLA USE 37716 35054 Sail Switch 35050 Sail Switch 35137 Sail Switch May Use 37716 NLA USE 37716 36040 Sail Switch Bracket Thermostats 38452 Thermostat brown Heat Only HFH 2000 38453 Thermostat...

Page 52: ...ional Shielded after S N 0657715 No Longer Available 36180 Wiring Harness Complete internal 36875 Wiring Harness Complete DC 37443 Wiring Harness Complete AC Miscellaneous 35121 24 VAC Transformer 364...

Page 53: ...2 35 000 BTU NAT 34092 30 40 000 BTU NAT Circuit Board 33686 Ignition Board Bracket 37515 Ignition Board Kit AC 36716 Ignition Board Kit DC Circuit Breaker 31028 Breaker 5 AMP 32331 Breaker 7 AMP Use...

Page 54: ...Use 38548 36997 Electrode 36998 Electrode Exhaust Tube Extensions 31680 79 80A 0 3 1 2 NLA Gaskets 34451 Bottom Discharge Gasket 34553 Bottom Discharge Gasket 31842 Burner Plate Gasket 31843 Burner P...

Page 55: ...l Cut Off 8900 II Thermostat 38452 Thermostat brown heat only 38453 Thermostat white heat only Valve 33716 ITT Valve Retrofit Kit pilot 33796 ITT FEN Valve Retrofit Kit Electronic Ignition 32697 Rober...

Page 56: ...P 32331 Breaker 7 AMP Use 33751 33590 Breaker 10 AMP Circuit Board 36716 Ignition Board Kit DC 37515 Ignition Board Kit AC Combustion 33124 Combustion Wheel Kit 31138 Combustion Wheel No Longer Availa...

Page 57: ...190 Switch 35282 Sail Switch 33697 Sail Switch Thermostat 38452 Thermostat brown heat only 38453 Thermostat white heat only Valves 33717 ITT Valve Retrofit Kit pilot 33688 ITT FEN Valve Retrofit Kit D...

Page 58: ...am seals on both sides 36278 Adapter plate for bottom discharge no seals but with alignment tabs Use with gasket 34551 36277 Extension plenum rear discharge to floor duct with one seal 33150 Adapter p...

Page 59: ...appliances and components found on RVs was something that I always had a desire to create I hope this resource makes your RV repairs easier as it has mine but please be careful and follow proper safe...

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