A.O. Smith BTX-80 SERIES 100 Instruction Manual

COMMERCIAL / RESIDENTIAL GAS WATER HEATERService HandbookPRINTED IN THE U.S.A. 0910 318558-000SERVICING SHOULD ONLY BE PERFORMED BY A QUALIFIED SERVI

8Servicing should only be performed by a Qualied Service AgentFEATURES AND COMPONENTSFRONT & BACK VIEWSHEATING LOOPRETURN LINECONNECTION3/4 INCH

9Servicing should only be performed by a Qualied Service AgentTOP VIEWBLOWERPROVERSWITCHCCB ENCLOSURE(central control board)3/4 INCH NPTWATER OUTLETW

10Servicing should only be performed by a Qualied Service AgentOPERATION AND SERVICEHOW IT WORKSThis section of the manual will cover operation, comm

11Servicing should only be performed by a Qualied Service AgentCOMBUSTION BLOWERThe Combustion Blower is an assembly that includes the blower housing

12Servicing should only be performed by a Qualied Service AgentBURNER ASSEMBLYThe Burner is a radial design burner with a steel ber jacket on the ou

13Servicing should only be performed by a Qualied Service AgentBURNER GROUNDWIREBURNERADAPTERBLOWER FLANGE WITH BLOWERDISCHARGE ORIFICE IN PLACEBURNE

14Servicing should only be performed by a Qualied Service AgentCOMBUSTION BLOWER AND BURNER REMOVALThe Combustion Blower and Burner Assembly must be

15Servicing should only be performed by a Qualied Service Agent6. Disconnect the 24 Volt power wires to the 24 Volt Gas Valve at the two spade conne

16Servicing should only be performed by a Qualied Service AgentBURNER ASSEMBLY REMOVAL1. Follow the instructions to remove the Combustion B

17Servicing should only be performed by a Qualied Service AgentBURNER ASSEMBLY INSTALLATION17. To re-install the Burner Assembly follow the steps for

18Servicing should only be performed by a Qualied Service AgentFLAME SENSORIgnition of the Burner is controlled electronically. The principle of oper

19Servicing should only be performed by a Qualied Service AgentFLAME SENSING CURRENT TESTDuring the heating cycle the ame sensing current is normal

20Servicing should only be performed by a Qualied Service AgentIGNITERThe water heaters covered by this manual use a hot surface igniter (HSI). The I

21Servicing should only be performed by a Qualied Service AgentIGNITER CURRENT TEST AT J5 SOCKET ON CCBIGNITER CURRENT TEST BEHIND CCB ENCLOSURE

22Servicing should only be performed by a Qualied Service AgentVENTURIA Venturi is mounted on the inlet of the Combustion Blower. All combustion air

23Servicing should only be performed by a Qualied Service AgentGAS VALVEThe 24 Volt Gas Valve on these water heaters is DC voltage valve. The CCB sen

24Servicing should only be performed by a Qualied Service AgentGAS VALVE REMOVALThe outlet of the 24 Volt Gas Valve is connected by ange directly to

25Servicing should only be performed by a Qualied Service AgentGAS PRESSUREThe water heater covered in this Service Manual is rated at 100,000 Btu/hr

26Servicing should only be performed by a Qualied Service AgentGAS PRESSURE TEST1. If the water heater is in a heating cycle lower the Operating Set

27Servicing should only be performed by a Qualied Service AgentGAS FLOW TESTThe following illustrations show the approximate pressures for the manifo

1TABLE OF CONTENTSTABLE OF CONTENTS ... 1INTRODUCTION ...

28Servicing should only be performed by a Qualied Service AgentPRESSURE SWITCHESThe water heaters covered in this manual are factory equipped with th

29Servicing should only be performed by a Qualied Service AgentCONTROL SYSTEM MONITORINGThe Control System monitors the “state” of the pressure switc

30Servicing should only be performed by a Qualied Service AgentThe three pressure switches monitor pressure through plastic sensing tube

31Servicing should only be performed by a Qualied Service AgentPRESSURE SWITCH TESTSComplete pressure switch testing involves three procedures:• Con

32Servicing should only be performed by a Qualied Service AgentCONTINUITY TEST DURING OPERATIONThis test is performed while the Combustion Blower is

33Servicing should only be performed by a Qualied Service AgentTABLE 3Blower Prover Blocked Intake Air †Activation Pressure +0.75"

34Servicing should only be performed by a Qualied Service AgentBLOWER PROVER SWITCHPRESSURE TESTBLOCKED INTAKE AIR SWITCHPRESSURE TESTBLOCKED EXHAUST

35Servicing should only be performed by a Qualied Service AgentTEMPERATURE PROBEThis section of the manual provides information on the Temperature Pr

36Servicing should only be performed by a Qualied Service AgentWATER TEMPERATURE TEMPERATURE SENSOR RESISTANCE IN OHMSCELSIUS FAHRENHEIT3° 40°

37Servicing should only be performed by a Qualied Service AgentCONTROL SYSTEM HARDWAREThis section of the manual will provide information on Control

2Servicing should only be performed by a Qualied Service AgentThis Service Manual covers the water heater Model and Series numbers listed on the fron

38Servicing should only be performed by a Qualied Service AgentUIM RIBBON CABLE CONNECTIONThe Ribbon Cable that connects the Button Pad

39Servicing should only be performed by a Qualied Service AgentThe CCB is a printed circuit board mounted inside a protect

40Servicing should only be performed by a Qualied Service AgentCCB COVER REMOVAL AND REPLACEMENTThe cover on the CCB enclosure must be removed for

3Servicing should only be performed by a Qualied Service AgentINSTALLATION CONSIDERATIONSThis section of the Service Manual covers some of the critic

4Servicing should only be performed by a Qualied Service AgentVENTINGThis section of the Service Manual is not a complete venting installation instru

5Servicing should only be performed by a Qualied Service AgentFACTORY SUPPLIED/INSTALLED FITTINGSFactory supplied vent and intake air terminations an

6Servicing should only be performed by a Qualied Service AgentELECTRICAL REQUIREMENTSThe water heaters covered in this manual require a 120 VAC (Volt

7Servicing should only be performed by a Qualied Service AgentINSTALLATION CHECK LISTThe list below represents some of the most critical installation