A.O. Smith BTH 120 - 250 Self Diagnostic Controller, Sequence of Operation, Item Description

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ITEM DESCRIPTION

1.Transformer

2.Control Board

3.E.C.O./Temperature Probe

4.Blower Proving Air Switch

5.Low Voltage Cable Assembly

6.

Line Voltage Cable Assembly

14.

Tubing-Pressure

7.

Blower/Motor Assembly

15.

Tubing-Pressure

8.

Igniter Assembly

16.

Connector-Tubing

9.

Cable To Control Display Board

17.

Switch-On/Off

10.

Control Display Board

18.

Low Gas Pressure

11.

Blocked Outlet Exhaust Switch

 

Switch

12.

Lower Temperature Probe

19.

Bocked Inlet Switch

13.

Wire Assembly-Gas Pressure

20.

Wire Assembly-Air

 

Switch

 

Flow Switch

FIGURE 17

OPERATION

SEQUENCE OF OPERATION

Typical Control/Appliance Operating Sequence

1.When the control is powered, it should first display “0”, then the input line voltage (“120”), the calibration setting (12), then the actual water temperature in the tank.

2.If the control determines that the actual water temperature inside the tank is below the programmed temperature setpoint less the differential, a call for heat is activated.

3.The control then performs selected system diagnostic checks. This includes confirming the proper state of the air switch and ECO limit device.

4.If all checks are successfully passed, the combustion blower is energized for the pre-purge cycle.

5.When the pre-purge cycle is complete, power is applied to the ignitor element for the ignitor warm-up period.

6.At the conclusion of the igniter warm-up period, the gas valve will open, allowing gas to enter the burner chamber.

7.The igniter will remain on for a short predetermined time period, then will be turned off.

8.After an additional 2 seconds, the control will monitor the flame sense probe to confirm a flame is present. If a flame is not verified within this time period, the gas valve will immediately be closed, and the blower will continue to run for approximately 10 seconds. The control will then return to step 2.

9.If a flame is confirmed, the control will enter the heating mode where it will continue heating the tank water until the setpoint temperature plus differential is reached. At this point, the gas valve is closed and the control enters the post-purge cycle.

10.The combustion blower will run for the duration of the post purge cycle to purge the system of all combustion gases. When the post purge cycle is complete, the blower is de-energized and will coast to a stop.

11.The control will now enter the idle state while continuing to monitor the internal tank water temperature and the state of other system devices. If the temperature drops below the setpoint value less differential, the control will automatically return to step 2 and repeat the entire operating cycle. During this idle state, if the control detects an improper operating state for external devices such as the ECO switch, vent switch, pressure switch, etc., the appropriate LED(s) on the Display Board will be illuminated indicating the nature of the fault.

SELF DIAGNOSTIC CONTROLLER

This controller is designed for ignition lockout after three consecutive failed attempts to light. If lockout occurs, the display lights will match Figure 18. Along with this, a numeric message will appear in the display. The following list of ERROR CODES illustrates possible numeric failures.

FIGURE 18

GAS VALVE LED FLASHING

This condition results from a failure to establish burner ignition after three successive trials. In such cases:

1.Investigate the possible cause and remedy any observations.

2.Momentarily depress the button on the display panel to reset the lockout condition.

3.Confirm proper appliance operation.

 

 

 

 

 

 

 

 

Possible Cause

 

Remedy

 

 

1.

Burner ground wire broken

1.

Check wire and connection

 

 

 

or corroded

 

at burner

 

 

2.

Connectors unplugged

2.

Check connections

 

 

3.

Igniter broken

3.

Replace igniter

 

 

4.

Flame probe faulty

4. Replace flame probe

 

 

5.

Gas shut off

5.

Turn on gas supply

 

 

6.

Clogged gas valve

6.

Replace gas valve

 

 

7.

Faulty gas valve

7.

Replace gas valve

 

 

8.

Defective control

8.

Replace control

 

 

9.

Burner improperly adjusted

9. Adjust burner

 

 

10.

Dirty burner

10.

Clean burner

 

 

 

 

 

 

 

 

 

 

 

 

 

15

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Contents Notify Owner to Keep for Future Reference Place These Instructions Adjacent to HeaterBTU ROUGH-IN -DIMENSIONS Cyclone XHE BTH 120Foreword Table of ContentsFeatures Water Temperature ControlHigh Limit Switch E.C.O Circulating Pump Installation InstructionsInsulation Blankets Dishwashing Machine RequirementMechanical Exhausting of Room AIR ClearancesHard Water AIR RequirementsPage Direct Vent Terminal Installation Direct VentingPVC Elbow with Mesh Screen Wooden Side Walls Installation SequenceVent Pipe Manufacturers Installation Instructions Masonry Side WallsInstallation of Vent System Vertical Vent Terminal InstallationControls and Switches Blower Prover SwitchVent Pipe Preparation GAS Piping System Connections Water Line Connections Heater Wiring Closed SystemBSR Board BTH 250 only Figure GAS Valve LED Flashing Self Diagnostic ControllerOperation Sequence of OperationFault Conditions Error CodesDisplay Flashes 05 when button is pressed Prior to Start UP Adjustment Procedure Operating InstructionsRequired Ability Initial START-UP For Your Safety Read Before Operating General Information MaintenanceSediment Removal Anode Inspection and ReplacementFlushing DrainingVent System Drain Valve and Access PanelsInstallation Diagrams Install in Accordance with Local Codes Page Page Page Manifold Kits TROUBLE-SHOOTING Checklist and Service InformationNoisy Burner Operation Replacement PartsMotor will not RUN Motor RUNS, Burner Lights Momentarily Then Locks OUTALL Other Parts Service and Repair ExpensesClaim Procedure TankSmith Water Products CO., INC

BTH 120 - 250 specifications

The A.O. Smith BTH 120 - 250 is a high-efficiency water heater designed for commercial and industrial applications, renowned for its advanced technology and durable construction. This model stands out for its ability to provide reliable hot water while minimizing energy consumption, making it an ideal choice for businesses looking to enhance operational efficiency.

One of the main features of the A.O. Smith BTH series is its innovative design that integrates cutting-edge condensing technology. This system maximizes energy use by capturing and reusing heat that would otherwise be lost in traditional water heating methods. As a result, the BTH 120 - 250 delivers exceptional thermal efficiency ratings, often exceeding 90%, thereby reducing overall operating costs.

The BTH series is available in various capacities, ranging from 120,000 to 250,000 BTU per hour, ensuring that it meets the diverse needs of different businesses. This flexibility allows for installation in a variety of settings, from small restaurants to large manufacturing facilities.

Another significant characteristic of the BTH 120 - 250 is its robust construction. Built with high-quality materials, this unit is designed to withstand the rigors of continuous use. Its stainless steel heat exchanger resists corrosion and scale build-up, providing longevity and reduced maintenance requirements.

Safety features are integrated into the BTH series as well. It includes an electronic ignition system that eliminates the need for a standing pilot light, enhancing operational safety and reducing energy waste. Additionally, the built-in diagnostic system allows for quick identification of issues, streamlining maintenance procedures.

The BTH series also emphasizes user-friendly operation. Equipped with advanced control options, operators can monitor and adjust performance settings effortlessly. The digital display provides real-time operational data, which can assist in optimizing performance and ensuring consistent hot water availability.

In summary, the A.O. Smith BTH 120 - 250 is an exceptional choice for commercial water heating, combining high efficiency, advanced technology, and robust durability. Its innovative design, safety features, and user-friendly controls position it as a trusted solution for businesses seeking reliable hot water systems. By investing in this model, operators can ensure optimal performance while enjoying significant energy savings over time.
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