A.O. Smith DB/DW-720-1810 Internal Contaminants, Precautions, Checking and Adjusting the Input

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INTERNAL CONTAMINANTS

The system must be internally cleaned and flushed after a new or replacement unit has been installed to remove contaminants that may have accumulated during installation. This is doubly important when a replacement unit is installed into an existing system where Stop Leak or other boiler additives have been used.

All systems should be completely flushed with a grease removing solution to assure trouble-free operation. Pipe joint compounds, soldering paste, grease on tubing and pipe all tend to contaminate a system.

Failure to clean and flush the system can cause solids to form on the inside of the heat exchanger, can produce acid concentrations that become corrosive, can allow excessive amounts of air or other gases to form which could block circulation, foul system accessories and damage circulator seals and impellers.

It is recommended that after installation, the boiler and system when filled should include the proper percentage of cleaning solution related to approximate water volume of the system. Fire and circulate for about one hour and then flush clean with fresh water. Commercial grease removing solutions are available.

PRECAUTIONS

If the unit is exposed to the following, do not operate boiler until all corrective steps have been made by a qualified serviceman:

1.Exposure to fire.

2.If damaged.

3.Firing without water.

4.Sooting.

If the heater has been exposed to flooding it must be replaced.

IMPORTANT

ONLY QUALIFIED PERSONNEL SHALL PERFORM THE INITIAL FIRING OF THE HEATER. AT THIS TIME THE USER SHOULD NOT HESITATE TO ASK THE INSTALLER ANY QUESTIONS REGARDING THE OPERATION AND MAINTENANCE OF THE UNIT.

CHECKING AND ADJUSTING THE INPUT

NOTE: For high altitude installations, calculate the input rate in accordance with the procedure in the HIGH ALTITUDE INSTALLATIONS in the OPERATING INSTRUCTIONS section.

1.Attach a pressure gauge or a manometer to the gauge port. Check for correct manifold pressure. PRESSURE SHOULD NOT EXCEED VALUE INDICATED ON RATING PLATE.

2.Use this formula to “clock” the meter. Be sure that other gas consuming appliances are not ON during this interval.

3600

T x H = Btuh

T= Time in seconds to burn one cubic foot of gas. H = Gas heating value (Btu per cubic foot of gas). Btuh = Actual boiler input per hour.

IMPORTANT

UNDER NO CIRCUMSTANCES SHALL THE GAS PRESSURE MEASURED AT THE BURNER MANIFOLD EXCEED THAT STATED ON THE BOILER RATING PLATE. OVERFIRING WILL RESULT IN DAMAGE TO THE BOILER, AS WELL AS INCREASED RISK OF FIRE, SOOTING AND ASPHYXIATION.

FIGURE 26

PILOT BURNER

The pilot flame should envelop 3/8 to 1/2 inch (10 to 12 mm) of the top of the insulated rod on the pilot burner, fig. 26. Normally, the pilot flame will be correct when the pilot manual valve is in the full “ON” position. Check pilot burner every 3 months for proper flame characteristics.

FIGURE 27

To adjust the pilot flame, remove the screw on the pilot gas regulator, fig. 27, to expose the adjustment screw. Turn the adjusting screw clockwise to increase the length of the flame or counterclockwise to decrease the length of the flame.

MAIN BURNER

Check main burner every three months for proper flame characteristics, fig. 28.

TYPICAL AND MAIN BURNER FLAMES

FIGURE 28

The main burner should display the following characteristics:

•Provide complete combustion of gas.

•Cause rapid ignition and carryover of flame across entire burner.

•Give reasonably quiet operation during initial ignition, operation and extinction.

•Cause no excessive lifting of flame from burner ports.

If the preceding burner characteristics are not evident, check for accumulation of lint or other foreign material that restricts or blocks the air openings to the burner or boiler.

NOTE: Cleaning of main burners.

Shut off all gas and electric to unit.

Complete burner tray assembly may be removed by disconnecting union assembly, pilot line connection at main burner and sliding tray out of cabinet.

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Contents Installation Operation Maintenance Limited Warranty TM Models DB/DW-720-1810Replacement Parts ContentsForeword Installation Clearances ROUGH-IN Dimensions CapacitiesLevelling Pressure Drop Manual Reset High Temperature Safety Limit Control FeaturesSafety Relief Valves Electronic Intermittent Pilot Ignition ControlThermal Balancer Automatic Reset High Temperature Limit ControlSafety Flow Switch Dual Stage Models only HIGH/LOW OperatorLocation Installation InstructionsRequired Ability AIR RequirementsDraft Hood Venting the BoilerVent Connection Connecting Boiler to a Common Vent GAS ConnectionsPurging Correct GASConventional Installations High Altitude InstallationsWiring Connections ExampleSystems Equipment Installation Circulating Pump Circulating Pump Must be Properly Sized for Your ApplicationConventional Space Heating Installation System InstallationTank Temperature Control LOW Water CutoffDB Installation Installation AS Boiler ReplacementPage LINEAR-TEMP Space Heating Installations LINEAR-TEMP Space Heating ApplicationsDuraMax Pump Performance Requirements Safety Flow Switch Thermometer Pressure GaugeONE Boiler LINEAR-TEMP System Page Page Page Page Page Page Hard Water Conditions ONE DURA-MAX Model DW Commercial Boiler with Vertical TankONE DURA-MAX Model DW Commercial Boiler with Horizontal Tank NPT NPT Manifolding of Model TJV-120M & TJV-200M Tanks START-UP and Operating Instructions For Your Safety Read Before Operating Internal Contaminants PrecautionsChecking and Adjusting the Input Pilot BurnerPRE-TROUBLE-SHOOTING TROUBLE-SHOOTINGNo Spark AT Pilot Burner YESSpark AT Pilot Burner but Pilot will not Light Pilot Burner Lights but Main Burner does not Light Heat Exchanger Preventive Maintenance General MaintenanceVenting Maintenance Relief ValveMechanical Removal of Deposits Deliming SolventsRemoving Light Deposits of Scale Removal of AN Existing Boiler from a Common Venting SystemDURA-MAX Limited Warranty Page Page Replacement Parts

DB/DW-720-1810 specifications

A.O. Smith has a longstanding reputation for quality and innovation in the water heater industry, and the DB/DW-720-1810 model exemplifies these values. This particular water heater is designed to provide reliable hot water, making it suitable for both residential and commercial applications. Its impressive features and cutting-edge technologies set it apart from conventional models.

One of the primary features of the A.O. Smith DB/DW-720-1810 is its energy efficiency. It operates using advanced insulation technologies, minimizing heat loss and promoting energy savings. This model is designed with a high-efficiency burner that substantially reduces energy consumption while maintaining optimal performance. It also complies with industry standards for energy efficiency, ensuring that users can enjoy lower utility bills without sacrificing comfort.

The DB/DW-720-1810 is equipped with a robust tank designed to hold an ample supply of hot water. With a capacity of 75 gallons, it is ideal for households with high demand, such as multi-bathroom residences or commercial establishments. This large capacity ensures that hot water is readily available for various activities, from bathing to cleaning.

User control is another notable characteristic of the A.O. Smith DB/DW-720-1810. The model features an intuitive digital display that allows users to monitor and set water temperatures easily. This interface not only enhances usability but also promotes safety, preventing scalding by allowing users to adjust the temperature to their preference.

Durability is a key consideration in the DB/DW-720-1810’s design. It is built with high-quality materials and features a corrosion-resistant tank, ensuring longevity even in challenging water conditions. This resilience is further supplemented by A.O. Smith's advanced anode rod technology, which helps battle corrosion and extends the lifespan of the water heater.

Lastly, maintenance is simplified with this model. A.O. Smith has designed the water heater for easy access to serviceable parts, making routine maintenance more convenient and less time-consuming. Coupled with warranty options that provide peace of mind, the DB/DW-720-1810 stands out as a dependable choice.

In summary, the A.O. Smith DB/DW-720-1810 combines energy efficiency, significant capacity, user-friendly controls, durability, and low maintenance needs, making it an exceptional option for those needing a reliable hot water solution.
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