A.O. Smith BTH 300A, BTH 400A warranty Motor will not RUN

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Checking these four (4) items first will often result in a timely solution to the service call.

WARNING

JUMPING OUT COMPONENTS AND/OR CIRCUITS DURING TROUBLESHOOTING CAN CAUSE SERIOUS PROBLEMS WITH THE UNIT’S OPERATING SEQUENCE AND IGNITION SAFETY. IF YOU DO NOT HAVE THE PROPER TEST EQUIPMENT, I.E. A VOLT-OHM METER AND A MICROMETER, DO NOT ATTEMPT TO TROUBLESHOOT OR REPAIR A.O. SMITH EQUIPMENT.

ALTERING THE CONTROLLER AND/OR CONTROLLER WIRING IN ANY WAY COULD RESULT IN INTERNAL DAMAGE TO THE MODULE CIRCUITS, POSSIBLY ALTERING THE IGNITION SEQUENCE ALLOWING GAS VALVES TO OPEN BEFORE THE HOT SURFACE IGNITER IS UP TO IGNITION TEMPERATURE.

NOTE: ANY BYPASS OR ALTERATION OF THE UNITS SAFETIES WILL RESULT IN VOIDING THE APPLIANCE WARRANTY.

Before performing any troubleshooting familiarize yourself with the particular appliance.

Refer to the SEQUENCE OF OPERATION and the connection diagram located on page 16 before continuing.

Make sure the appliance is connected to a 120V AC power supply, manual gas valve is in the ON position, and all electrical connections are secure before continuing to troubleshoot this appliance.

CAUTION

THE WATER HEATER IS POLARITY SENSITIVE. BEFORE APPLYING ELECTRICITY TO THIS HEATER BE CERTAIN THAT SUPPLY NEUTRAL WIRE TO GROUND CHECK INDICATES ZERO VOLTAGE.

MOTOR WILL NOT RUN

1.Confirm 120V AC. Also, to verify correct polarity, check for 120 V AC between hot supply and ground. If there is no voltage, check for a loose connection.

2.For BTH 400, a VFD (Variable Frequency Drive) is used. "rdy" (stands for ready) will be shown on display in standby heating mode. "152" (152 output Hz) shall be shown on VFD display during heater running. Any other display (other than "rdy" or "152") indicates the VFD fault. Check 120V AC to the VFD power input L1 and N terminals. Check the open contact of the relay (mounted on VFD) wired to VFD terminal +15V and LI1. When calling for heat, the relay should be energized, the relay contact will change from "open" to "close", and VFD display will change from "rdy" to "152", and blower starts to run. If there's no display change (from "rdy" to "152") on VFD during the call for heat, check the wire from the controller blower connector to the relay A1 and A2 terminal or replace the relay coil.

MOTOR RUNS, PREPURGE TIME ELAPSES BUT

MAIN FLAME NOT ESTABLISHED

1.Check to see if main manual gas valve is open.

2.Check for a loose connection at the transformer, or a defective transformer.

3.Check for a loose connection at the gas valve.

4.Check for open pressure switches or open reset button. Check for blockage in the intake and exhaust venting or at the vent hoods. If no blockage is found, check vinyl tubing for cuts or crimps. If this tubing is damaged it must be replaced. If these steps do not eliminate the problem, replace the pressure switches.

5.Check to see if there is resistance across the igniter terminal with an OHM meter. If there is no continuity, the igniter is broken and should be replaced.

If the igniter appears to function properly, then verify that the inlet pressure is 11.0" Natural Gas (2.74 kPa). The gas valve supplied on this appliance is not designed to open against a higher pressure. At this time also check that the inlet pressure is not lower than the minimal gas supply pressure, as shown in Table 4: that is, for Natural Gas, 5.2" (1.29 kPa) W.C. If the inlet pressure is not within these limits then adjust the supply pressure accordingly.

If the inlet pressure falls within the allowable limits, then verify that the manifold pressure, when the gas is fully open, with the heater running, is as called out in Table 4: that is, for Natural Gas, 4.0" (0.996 kPa) W.C. If the manifold pressure is not correct then adjust accordingly. See ADJUSTMENT PROCEDURE in OPERATING INSTRUCTIONS selection, page 19, for the manifold pressure adjustment procedure.

6.If the inlet and manifold pressures are within the limits specified in step 5, then reset the appliance. Verify 24V AC at the gas valve during the three (3) second ignition trial, after the igniter reaches operating temperature. If 24V AC at the gas valve is not seen during this period, the controller must be replaced.

If there is 24V AC at the gas valve during the four second ignition trial and the manifold pressure does not increase above 0" W.C. then verify that the manual gas control valve is in the “ON” position (see page 20). If the valve is in the “ON” position and the previous voltage and gas pressure conditions are met, then the gas valve is defective and must be replaced.

Note that a positive manifold pressure reading of approximately 1.5" (.38 kPa) W.C. is normal during the prepurge portion of the ignition cycle due to the location of the gas orifice.

MOTOR RUNS, BURNER LIGHTS MOMENTARILY,

THEN LOCKS OUT

1.Reset the appliance two more times to ensure that all of the air has been purged from the gas line.

2.If the burner lights momentarily but does not sustain ignition, verify that the inlet pressure is not greater than 11.0" (2.74 kPa) W.C. or lower than the minimal gas supply pressure, as shown in Table 4: that is, for Natural Gas, 5.2" (1.29 kPa) W.C. pressure. Also, the manifold pressure should rise during the three (3) second trial for ignition to the manifold pressure value for the individual unit listed in Table 4: that is, for Natural Gas, 4.0" (0.996 kPa) W.C. If the manifold pressure is not correct then adjust accordingly. See ADJUSTMENT PROCEDURE in OPERATING INSTRUCTIONS section, page 19, for the manifold pressure adjustment procedure.

3.Check for the reversed polarity in the supply wiring. This controller is polarity sensitive. If the hot and neutral supply wires are reversed, the controller will not sense flame. Reverse the supply wires and try to fire the unit.

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Contents Cyclone XHE Model BTH 300A and 400A ROUGH-IN-DIMENSIONS ForewordGAS Valve Piping Features Table of ContentsHorizontal Sidewall Venting Vertical Rooftop Venting Quick Installation TipsWater Temperature Setpoint Adjustment Procedure High Limit Switch E.C.ODishwashing Machine Requirement Circulating Pump Installation InstructionsRequired Ability Insulation BlanketsHard Water ClearancesUnconfined Space Confined SpaceCanadian Direct Vent US Direct VentCanadian Horizontal Vent US Horizontal VentDirect Vent Terminal Installation Vent Pipe TerminationDirect Venting Vertical Vent Terminal Installation Installation SequenceVent Length Table Installation of Vent SystemBlower Prover Switch Controls and SwitchesBlocked Outlet Prover Switch Blocked Inlet Prover SwitchHOT Surface Igniter GAS PipingConnection of GAS Pipe System Connections Heater Wiring Page Operation Self Diagnostic ControllerSequence of Operation GAS Valve LED FlashingFault Conditions Error CodesECO Switch OPEN. See Figure Adjustment Procedure Initial START-UP Operating InstructionsPrior to Start UP Required Ability What to do if YOU Smell GAS Operating InstructionsGeneral Information Flushing Maintenance ScheduleDraining Sediment RemovalPowered Anode Operation Powered Anode SystemPower Supply LED Meanings Drain Valve and Access PanelsInstallation Diagrams Install in Accordance with Local Codes Must be Identical Heaters Install in Accordance with Local Codes Page Manifold Kits Not Enough or no HOT Water Burner Operational ProblemsWater is TOO HOT Water Heater Makes SoundsMotor RUNS, Burner Lights Momentarily Then Locks OUT Motor will not RUNReplacement Parts Noisy Burner OperationGAS Fails to Shut OFF Model BTH Limited Warranty

BTH 300A, BTH 400A specifications

A.O. Smith has established itself as a leader in the water heating industry, offering a range of products that combine efficiency, reliability, and innovative technology. Among these products, the BTH 300A and BTH 400A models stand out for their advanced features and robust performance, catering to both residential and commercial needs.

The BTH 300A and BTH 400A are high-efficiency water heaters designed with cutting-edge condensing technology, allowing for significant energy savings compared to traditional water heating systems. These models utilize a modulating gas valve that adjusts the burner operation based on the demand for hot water. This smart system not only enhances efficiency but also ensures a consistent supply of hot water without the worry of fluctuations.

One of the standout features of the BTH series is its compact design. Both the BTH 300A and BTH 400A are engineered to fit into smaller spaces, making them ideal for properties with limited installation areas. Their lightweight construction and user-friendly installation features further simplify the process, ensuring that homeowners and professionals alike can set them up with ease.

The BTH models are equipped with advanced control systems that offer precise temperature adjustment capabilities. Users can easily customize their hot water settings to meet specific household or business requirements. This adaptability is supported by the built-in digital display, which provides real-time information about the operating status of the unit.

Safety is a key consideration in the design of the BTH 300A and BTH 400A. They feature a robust set of safety mechanisms, including temperature lockout and venting safeguards, ensuring reliable operation and peace of mind for users. A.O. Smith also understands the importance of longevity in water heaters, and these models are built with high-quality materials, making them resistant to corrosion and wear over time.

In terms of performance, both the BTH 300A and BTH 400A models deliver exceptional heating capabilities, capable of meeting high demands while maintaining efficiency. With customer satisfaction at the forefront, A.O. Smith backs these units with an extensive warranty, demonstrating their commitment to quality and long-term performance.

In summary, the A.O. Smith BTH 300A and BTH 400A water heaters exemplify the marriage of innovation and functionality. With their energy-efficient operation, customizable settings, compact design, and advanced safety features, these models are a compelling choice for those in need of reliable and effective hot water solutions.
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