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A.O. Smith BTX 100 Service Handbook

Other manuals for BTX 100: Instruction Manual
Manual is about: SERIES 120 & 121 Commercial / Residential gas water heater

Summary of BTX 100

  • Page 1

    Commercial / residential gas water heater service handbook printed in the u.S.A. 0410 318556-000 servicing should only be performed by a qualified service agent 500 tennessee waltz parkway ashland city, tn 37015 for models: btx 100, gdhe 50 series 120 & 121 installation considerations - pre service ...

  • Page 3: Table Of Contents

    1 table of contents table of contents .......................................................................... 1 introduction .................................................................................... 2 qualifications .........................................................................

  • Page 4: Introduction

    2 servicing should only be performed by a qualified service agent this service manual covers the water heater model and series numbers listed on the front cover only. The instructions and illustrations contained in this manual will provide you with troubleshooting procedures to verify proper operati...

  • Page 5: Installation Considerations

    3 servicing should only be performed by a qualified service agent installation considerations this section of the service manual covers some of the critical installation requirements that, when overlooked, often result in operational problems, down time and needless parts replacement. Costs to corre...

  • Page 6

    4 servicing should only be performed by a qualified service agent venting this section of the service manual is not a complete venting installation instruction. Refer to the instruction manual that came with the water heater; ensure the venting has been installed per all instruction manual requireme...

  • Page 7

    5 servicing should only be performed by a qualified service agent factory supplied/installed fittings factory supplied vent and intake air terminations and factory installed fittings on the water heater are not factored in to the vent and intake air pipe equivalent feet calculations. The intake air ...

  • Page 8

    6 servicing should only be performed by a qualified service agent electrical requirements the water heaters covered in this manual require a 120 vac (volts alternating current) 1Ø (single phase) power supply. The maximum ac amperage is approximately 5.2 fla (full load amps) during the igniter warm u...

  • Page 9

    7 servicing should only be performed by a qualified service agent installation check list the list below represents some of the most critical installation requirements that, when overlooked, often result in operational problems, down time and needless parts replacement. Before performing any trouble...

  • Page 10: Features And Components

    8 servicing should only be performed by a qualified service agent features and components front & back views heating loop return line connection 3/4 inch npt drain valve temperature pressure relief valve front view back view exhaust elbow (2 inch pvc vent connection) condensate drain connection bloc...

  • Page 11

    9 servicing should only be performed by a qualified service agent top view blower prover switch ccb enclosure (central control board) 3/4 inch npt water outlet with outlet anode rod 3/4 inch npt water inlet blocked exhaust switch temperature pressure relief valve burner sight glass front 1/2 inch su...

  • Page 12

    10 servicing should only be performed by a qualified service agent operation and service how it works this section of the manual will cover operation, common service procedures and water heater construction. The water heater covered in this manual has a helical shaped coil heat exchanger that is sub...

  • Page 13

    11 servicing should only be performed by a qualified service agent combustion blower the combustion blower is an assembly that includes the blower housing, blower motor and an electronic speed control. The combustion blower is controlled by the ccb (central control board), see control system hardwar...

  • Page 14

    12 servicing should only be performed by a qualified service agent burner assembly the burner is a radial design burner with a steel fiber jacket on the outer surface and is part of a larger burner assembly. Figure 8 and figure 9 below show side views of the complete burner assembly removed from the...

  • Page 15

    13 servicing should only be performed by a qualified service agent burner ground wire burner adapter blower flange with blower discharge orifice in place burner adapter wiring harness igniter/flame sensor figure 10 burner sight glass burner adapter wiring harness igniter/flame sensor blower discharg...

  • Page 16

    14 servicing should only be performed by a qualified service agent combustion blower and burner removal the combustion blower and burner assembly must be removed to inspect the burner and to service the flame sensor and igniter. This section will provide instructions on how to remove and inspect the...

  • Page 17

    15 servicing should only be performed by a qualified service agent 6. Disconnect the 24 volt power wires to the 24 volt gas valve at the two spade connectors in the wiring harness to the valve, see figure 14 below. 7. Disconnect the blower prover switch sensing tube from the combustion blower outlet...

  • Page 18

    16 servicing should only be performed by a qualified service agent figure 15 burner assembly removal 1. Follow the instructions to remove the combustion blower beginning on page 14. 2. Remove the blower discharge orifice from the top of the burner adapter. 3. Unplug the burner adapter wiring harness...

  • Page 19

    17 servicing should only be performed by a qualified service agent burner assembly installation 17. To re-install the burner assembly follow the steps for removal in reverse order. 18. Install a new white fiber gasket between the burner adapter and the heat exchanger flange on top of the water heate...

  • Page 20

    18 servicing should only be performed by a qualified service agent flame sensor ignition of the burner is controlled electronically. The principle of operation for electronic ignition relies on flame sensing current to prove the fuel gas flowing to the burner has been ignited and is burning safely. ...

  • Page 21

    19 servicing should only be performed by a qualified service agent flame sensing current test during the heating cycle the flame sensing current is normally between 8.0 μa and 12.0 μa with a clean flame sensor. Over time the flame sensor will accumulate corrosion (rust) and this will reduce flame se...

  • Page 22

    20 servicing should only be performed by a qualified service agent igniter the water heaters covered by this manual use a hot surface igniter (hsi). The igniter is made of a ceramic composite material, see figure 20 below. The control system powers the igniter (120 vac) from the j5 socket on the ccb...

  • Page 23

    21 servicing should only be performed by a qualified service agent igniter current test at j5 socket on ccb igniter current test behind ccb enclosure figure 21 service notes: • the animated lighting bolt status icon is visible on the lcd desktop screen during the igniter warm up operating state. See...

  • Page 24

    22 servicing should only be performed by a qualified service agent venturi a venturi is mounted on the inlet of the combustion blower. All combustion air flows through the venturi. The outlet of the 24 volt gas valve connects directly to the side of the venturi. Fuel gas flows from the outlet of the...

  • Page 25

    23 servicing should only be performed by a qualified service agent gas valve the 24 volt gas valve on these water heaters is dc voltage valve. The ccb sends 24 vac to the valve and the ac voltage is rectified into a dc voltage by electronics contained inside the plug end of the 24 volt gas valve wir...

  • Page 26

    24 servicing should only be performed by a qualified service agent gas valve removal the outlet of the 24 volt gas valve is connected by flange directly to the side of the venturi and is secured by three - 5/32” hex head screws. A gas orifice with gasket is fitted into the gas valve’s outlet flange,...

  • Page 27

    25 servicing should only be performed by a qualified service agent gas pressure the water heater covered in this service manual is rated at 100,000 btu/hr input. It is certified for elevations up to 10,100 feet (3,078 meters). For higher elevations call the toll free support phone number shown on th...

  • Page 28

    26 servicing should only be performed by a qualified service agent gas pressure test 1. If the water heater is in a heating cycle lower the operating set point to end the cycle, see temperatures on page 49. 2. Turn off power to the water heater at the water heater's on/off switch. 3. Turn off the su...

  • Page 29

    27 servicing should only be performed by a qualified service agent gas flow test the following illustrations show the approximate pressures for the manifold offset and supply gas for the standby, pre-purge and heating operating states during a normal heating sequence. Notice how the manifold offset ...

  • Page 30

    28 servicing should only be performed by a qualified service agent pressure switches the water heaters covered in this manual are factory equipped with three pressure switches. Figure 4 on page 9 shows the location of the three pressures switches on top of the water heater. This section of the manua...

  • Page 31

    29 servicing should only be performed by a qualified service agent control system monitoring the control system monitors the “state” of the pressure switch contacts individually through three separate circuits, see wiring diagram on page 44. The state of the switch refers to whether the switch conta...

  • Page 32

    30 servicing should only be performed by a qualified service agent sensing tubes the three pressure switches monitor pressure through plastic sensing tubes from three different sensing ports on the water heater, see figure 32 below. The blower prover switch monitors pressure from the combustion blow...

  • Page 33

    31 servicing should only be performed by a qualified service agent pressure switch tests complete pressure switch testing involves three procedures: • continuity test during standby below. • continuity test during operation on page 32. • pressure test during operation on page 32. Continuity test dur...

  • Page 34

    32 servicing should only be performed by a qualified service agent continuity test during operation this test is performed while the combustion blower is running at high speed during the pre-purge operating state. The test is performed on all three pressure switches. Disconnect the two wires to each...

  • Page 35

    33 servicing should only be performed by a qualified service agent table 3 blower prover blocked intake air blocked exhaust †activation pressure +0.75" w.C. -2.00" w.C. +2.00" w.C. Tolerance ± 0.05" w.C. ± 0.05" w.C. ± 0.05" w.C. †though it is uncommon, pressure switch specifications can be changed ...

  • Page 36

    34 servicing should only be performed by a qualified service agent blower prover switch pressure test blocked intake air switch pressure test blocked exhaust switch pressure test figure 34.

  • Page 37

    35 servicing should only be performed by a qualified service agent temperature probe this section of the manual provides information on the temperature probe, see figure 3 on page 8 for location. The temperature probe contains the eco (energy cut out) and a temperature sensor. The temperature probe ...

  • Page 38

    36 servicing should only be performed by a qualified service agent table 4 water temperature temperature sensor resistance in ohms celsius fahrenheit 3° 40° 26,435 21° 70° 11,974 38° 100° 5,862 49° 120° 3,780 55° 130° 3,066 60° 140° 2,503 71° 160° 1,698 82° 180° 1,177 eco continuity test 1. Turn off...

  • Page 39

    37 servicing should only be performed by a qualified service agent control system hardware this section of the manual will provide information on control system hardware , operation and service procedures. See control system operation on page 45 for information on control system features, navigation...

  • Page 40

    38 servicing should only be performed by a qualified service agent uim ribbon cable connection service notes: the ribbon cable that connects the button pad overlay to the uim circuit board must be plugged in exactly as shown in figure 36 on page 37. The metal crimp connections in the ribbon cable pl...

  • Page 41

    39 servicing should only be performed by a qualified service agent ccb (central control board) the ccb is a printed circuit board mounted inside a protective plastic enclosure, see figure 38 and figure 39 below. The ccb circuit board is the main control. All instructions for ignition and temperature...

  • Page 42

    40 servicing should only be performed by a qualified service agent ccb cover removal and replacement the cover on the ccb enclosure must be removed for various service procedures outlined in this manual. Refer to the instructions on page 40 when removing and replacing the ccb cover. Wiring to and fr...

  • Page 43

    41 servicing should only be performed by a qualified service agent ccb circuit board layout 1 retry use yes type tstat spare ext input 3 retries no vent spare o pe n 1 2 3 4 3 2 1 6 5 4 9 8 7 12 11 10 15 14 13 j6 j7 3 2 4 1 1 2 j15 8 4 5 6 7 1 2 3 j13 3 4 1 2 j10 1 3 5 2 4 j1 1 3 4 2 j2 1 4 2 1 2 j3...

  • Page 44

    42 servicing should only be performed by a qualified service agent ccb connection identification j1 socket - transformer pin # description 1 120 vac hot to transformer 2 not used 3 120 vac neutral to transformer 4 24 vac out from transformer 5 24 vac out from transformer j2 socket - 120 vac to combu...

  • Page 45

    43 servicing should only be performed by a qualified service agent ccb connection identification (cont) j7 socket - temperature probe/eco (immersion probe) pin # description 1 eco (energy cut out) 24 vac out (red wire) 2 temperature sensor (thermistor) +5.0 vdc (black wire) 3 temperature sensor (the...

  • Page 46

    44 servicing should only be performed by a qualified service agent wiring diagram 2 green white red black 1 1 2 black 3 white combustion blower temperature probe 1 red (eco) 4 red (eco) 2 black 3 black 1 black120 vac hot 3 white 120 vac neutral 4 yel 24 vac 4 yel 24 vac hot surface igniter flame sen...

  • Page 47: Control System Operation

    45 servicing should only be performed by a qualified service agent control system operation overview this section of the manual provides instructions and information on control system features, navigation, menus, and user settings. See control system hardware on page 37 for information concerning th...

  • Page 48

    46 servicing should only be performed by a qualified service agent commercial and residential models the water heaters covered by this manual are produced for commercial and residential use. The control system is programmed differently for commercial and residential models. There are two differences...

  • Page 49

    47 servicing should only be performed by a qualified service agent status icons the status icons are displayed on the desktop screen and convey operational and diagnostic information. The icons are described in the table below. Table 5 icon description water temperature in the tank has fallen. Shade...

  • Page 50

    48 servicing should only be performed by a qualified service agent operating states the current operating state of the water heater is displayed on the desktop screen as the "status." the common operational states are described in the table below. Table 6 state description standby the water heater i...

  • Page 51

    49 servicing should only be performed by a qualified service agent temperatures operating set point and differential adjustment the operating set point is adjustable from 90°f (42°c) to 180°f (82°c) for commercial and 160°f (71°c) on residential models. The factory setting is 120°f (49°c). The diffe...

  • Page 52

    50 servicing should only be performed by a qualified service agent temperatures menu description/action display • tank temperature - non adjustable - control system sensed temperature from the temperature probe. • tank probe offset - adjustable user setting, range -5° to +5° (factory setting 0°). Th...

  • Page 53

    51 servicing should only be performed by a qualified service agent display settings description/action display select display settings from the main menu and press the operational button under "select" to enter this menu. This menu contains adjustable display options for viewing information on the l...

  • Page 54

    52 servicing should only be performed by a qualified service agent current fault description/action display select current fault from the main menu and press the operational button under "select" to enter this menu. This menu contains non adjustable operational information. Use the up & down buttons...

  • Page 55

    53 servicing should only be performed by a qualified service agent service contact information there is a discrete menu that installing contractors and/or service agents can access to enter contact information for their customers. This contact information will be displayed with all fault and alert m...

  • Page 56

    54 servicing should only be performed by a qualified service agent sequence of operation read the sequence of operation below before attempting to diagnose or repair any operational problems. Refer to the features and components on page 8 for the location of various water heater components described...

  • Page 57

    55 servicing should only be performed by a qualified service agent sequence of operation flow chart if tank temperature drops below operating set point minus differential setting a heating cycle is activated control system performs diagnostic system check normal state of all pressure switches and ec...

  • Page 58: Troubleshooting

    56 servicing should only be performed by a qualified service agent troubleshooting the control system performs exhaustive self diagnostics and displays detected fault conditions in plain english fault messages on the lcd when there is a problem. When the control system declares a fault condition it ...

  • Page 59

    57 servicing should only be performed by a qualified service agent control system unresponsive displayed message/condition/indicates possible causes - check/repair uim (lcd) is blank the lcd on the uim is not showing any data. The water heater may be running and maintaining hot water or it may not b...

  • Page 60

    58 servicing should only be performed by a qualified service agent fault messages displayed message/condition/indicates possible causes - check/repair ac reversed the control system has detected the power supply polarity is reversed. Change back advanced ac reversed fault occurred 2 mins ago power s...

  • Page 61

    59 servicing should only be performed by a qualified service agent fault messages displayed message/condition/indicates possible causes - check/repair flame sensor short the control system has detected the flame sensor is grounded. Change back advanced flame sensor short fault occurred 2 mins ago th...

  • Page 62

    60 servicing should only be performed by a qualified service agent fault messages displayed message/condition/indicates possible causes - check/repair energy cut out (eco) the control system has detected water temperature in the water heater storage tank above 201°f (94°c). Tank temperature must coo...

  • Page 63

    61 servicing should only be performed by a qualified service agent fault messages displayed message/condition/indicates possible causes - check/repair blocked air intake the control system has detected the blocked intake air switch has open contacts - restricted combustion air intake to the water he...

  • Page 64

    62 servicing should only be performed by a qualified service agent fault messages displayed message/condition/indicates possible causes - check/repair blocked exhaust the control system has detected the blocked exhaust switch has open contacts - restricted/blocked vent piping, the water heater is no...

  • Page 65

    63 servicing should only be performed by a qualified service agent fault messages displayed message/condition/indicates possible causes - check/repair blower prover open (combustion blower not running) the control system has detected the blower prover switch has open contacts after the combustion bl...

  • Page 66

    64 servicing should only be performed by a qualified service agent fault messages displayed message/condition/indicates possible causes - check/repair low igniter current the control system has detected less than 0.5 ac amps through the igniter during the igniter warm up operating state. See the seq...

  • Page 67

    65 servicing should only be performed by a qualified service agent fault messages displayed message/condition/indicates possible causes - check/repair ignition failure the control system has detected less than 1.0 μa (dc micro amps) through the flame sensor during the ignition verification operating...

  • Page 68

    66 servicing should only be performed by a qualified service agent fault messages displayed message/condition/indicates possible causes - check/repair ignition failure the control system has detected less than 1.0 μa (dc micro amps) through the flame sensor during the ignition verification operating...

  • Page 69

    Notes.

  • Page 70

    Notes.

  • Page 72

    500 tennessee waltz parkway, ashland city, tn 37015 technical support: 800-527-1953 • parts: 800-433-2545 • fax: 800-644-9306 www.Hotwater.Com.