A.O. Smith HW-120M, 225M, 200M Preventive Maintenance, GAS Pressure Regulator, Electrical Service

Page 22

CAUTION

DO NOT USE A NYLON BRUSH OR OTHER STATIC CREATING MATERIAL TO CLEAN DUST AND CARBON DEPOSITS FROM HEATING SURFACES AND VENT.

SUCH DEPOSITS ARE FLAMMABLE AND MAY BE IGNITED BY STATIC ELECTRICITY. USE A METAL BRUSH TO MINIMIZE THE DANGER OF EXPLOSION.

1.Turn off the electrical power and main manual gas shutoff valve.

•Allow heater parts and vent to cool before disassembly.

2.Remove the heater draft diverter and vent pipe running to the chimney.

•Check parts and chimney for obstructions and clean as necessary.

•Replace any damaged or deteriorated parts of the venting system.

3.Remove burners from heater and other metal parts as required to clean and vacuum the heat exchangers and combustion coils.

•Refer to parts list supplied with this manual for disassembly aid.

4.Reinstall the parts removed in steps 2 and 3.

•Be sure the vent pipe has a minimum upward pitch of one quarter inch per foot of length and is sealed as necessary.

5.Restore electrical power and gas supply to heater.

•Check for gas leaks and proper heater and vent operation.

Upon reassembly, a negative draft must be produced by the system. Check for proper draft by holding a lit match near the draft hood opening while the heater is operating. The flame should be drawn into the draft hood opening indicating proper draft.

GAS PRESSURE REGULATOR

The gas pressure regulator is included in the combination gas valve, fig.14, and is set to operate on the gas specified on the heater model and rating plate.

Periodically check main burner, fig. 13, and pilot flame, fig. 15, for proper operation. This should be checked every six months.

Do not subject the gas valve to inlet gas pressure of more than 10.5" W.C. - natural gas, 13.0" W.C. - propane gas. If higher gas pressures are encountered, a service regulator is necessary.

Check for a minimum inlet gas pressure value shown on the Rating Plate before making any adjustment of the regulator.

Attempts to adjust the regulator during periods of low gas supply pressure could result in overfiring of the heater when the gas supply pressure returns to normal.

DO NOT INCREASE PRESSURE ABOVE THAT SPECIFIED AS OVERFIRING WILL RESULT IN DAMAGE TO THE HEATER

.

If gas pressure regulator cannot be adjusted to correct pressure

with sufficient gas pressure at the valve, replace with new gas valve.

RELIEF VALVE

At least twice a year the system relief valves should be checked to ensure that they are in operating condition. To check a relief valve, lift the lever at the end of the valve several times. The valve should seat properly and operate freely.

CAUTION

BEFORE MANUALLY OPERATING A RELIEF VALVE, MAKE SURE THAT A DRAIN LINE HAS BEEN ATTACHED TO THE VALVE TO DIRECT DISCHARGE TO AN OPEN DRAIN. FAILURE TO TAKE THIS PRECAUTION COULD MEAN CONTACT WITH EXTREMELY HOT WATER EXITING THE VALVE DURING THE CHECK OPERATION.

If a relief valve discharges periodically or continuously, it may be due to thermal expansion of water in a closed water supply system, or, it may be due to a faulty relief valve.

Thermal expansion is the normal response of water when it is heated. In a closed system, thermal expansion will cause the system pressure to build until the relief valve actuation pressure is equaled. Then the relief valve will open allowing some water to escape, slightly lowering the pressure.

Installation of a properly sized thermal expansion tank will usually correct this problem. Contact your water supplier or local plumbing inspector for information on how to best correct this situation.

ABOVE ALL DO NOT PLUG ANY RELIEF VALVE. THIS IS NOT A SOLUTION AND CAN CREATE A HAZARDOUS SITUATION.

CIRCULATING PUMP

The circulating pump may require occasional lubrication. Refer to circulator manufacturer’s instructions for lubrication procedures, and lubrication frequency.

ELECTRICAL SERVICE

CAUTION

LABEL ALL WIRES PRIOR TO DISCONNECTION WHEN SERVICING CONTROLS. WIRING ERRORS CAN CAUSE IMPROPER AND DANGEROUS OPERATION.

VERIFY PROPER OPERATION AFTER SERVICING.

REPLACEMENT PARTS

Replacement parts may be ordered through A. O. Smith dealers, authorized servicers or distributors. Refer to the Yellow Pages for where to call or contact the A. O. Smith Water Products Company, 5621 West 115th Street, Alsip, IL 60803, 1-800-433-2545, or on the web at www.hotwater.com/parts. When ordering parts be sure to state the quantity, part number and description of the item including the complete model and serial number as it appears on the product. Refer to the parts list for more information.

PREVENTIVE MAINTENANCE

RECOMMENDED PROCEDURE FOR PERIODIC REMOVAL OF LIME DEPOSITS FROM COIL TYPE COMMERCIAL WATER HEATERS

The amount of calcium carbonate (lime) released from water is in direct proportion to water temperature and usage, see fig. 17.

The higher the water temperature or water usage, the more lime deposits are dropped out of the water. This is the lime scale which forms in pipes, heaters and on cooking utensils.

Lime accumulation not only reduces the life of the equipment, but also reduces efficiency of the heater and increases fuel consumption.

22

Page 21 Page 23
Image 22
Page 21 Page 23
Contents Models HW-120M, 160M, 200M, 225M Commercial GAS Copper Heat Exchanger Water HeaterROUGH-IN-DIMENSIONS Heater Performance DataGeneral Safety Information Table of ContentsForeword Chemical Vapor Corrosion High Altitude InstallationsGrounding Instructions Liquid Petroleum ModelsThermal Balancer FeaturesAutomatic GAS Shutoff Control Intermittent Ignition Control ModuleCirculating Pump Tank Temperature ControlSafety Flow Switch Intermittent Ignition Control Module I.I.DSafety Flow Switch Settings Drain Valve Not SuppliedInstallation Instructions Relief Valve Proper Vent Pipe InstallationVenting Confined SpaceWater Line Connections Hard WaterClosed Water System Water Potable HeatingPiping Diagrams Page Page Sizing GAS Supply Line GAS ConnectionsCorrect GAS GAS Supply Pipe Sizes in InchesElectrical Information Page Filling OperationGeneral Purging of GAS LineFor Your Safety Read Before Operating Operating Instructions for I.I.D. ModelsChecking and Adjusting the Input Over 170F 77CD. Pilot Burner Service InformationPilot and Main Burner Maintenance Main Burner for HW HeatersThermal Balancer Schematic Diagram Protector SwitchProtector Switch Continuity Test Inspecting the Heat Exchanger Venting SystemReplacement Parts Preventive MaintenanceElectrical Service GAS Pressure RegulatorHeavy Lime Deposits Deliming SolventsRemoving Light Deposits Deliming the HW Water HeaterRemoving Silicate CheckoutSystem Operation No Spark AT Pilot Burner YESSpark AT Pilot Burner but Pilot will not Light Replace pilot burner Replace ignition ModulePilot Burner Lights but Main Burner does not Light MV & MV/PV?Conditions and Exceptions Service and Repair ExpensesClaim Procedure Limitations on Implied Warranties

HW-120M, 225M, 200M, 160M specifications

A.O. Smith is renowned for its range of advanced water heaters, and the 160M, 200M, 225M, and HW-120M models stand out as some of the most reliable and innovative options available. These water heaters are designed to deliver exceptional performance, energy efficiency, and user-friendly features, making them ideal for various residential and commercial applications.

The A.O. Smith 160M model boasts a robust design that ensures longevity and efficiency. It has a 160-gallon capacity, providing ample hot water for households with high demand. This model incorporates insulation technology that minimizes heat loss, contributing to energy savings and reduced utility bills. Additionally, it features a durable exterior that is resistant to rust and corrosion.

The 200M model takes performance a step further with a higher capacity of 200 gallons, making it suitable for larger homes or businesses. This model is equipped with advanced components, including a high-efficiency burner and a powerful thermocouple that ensures reliable heating. The 200M also includes user-friendly controls that allow for precise temperature settings and easy operation.

Next in line is the A.O. Smith 225M, which offers an impressive 225-gallon capacity. This model is designed for heavy-duty usage and features a reinforced tank to withstand high pressure. The 225M is also equipped with state-of-the-art flame retention technology that optimizes fuel use, enhancing the overall efficiency of the unit. This ensures that customers not only get hot water when needed but also experience considerable savings on energy costs.

Finally, the HW-120M model is a compact solution that does not compromise on performance. With a capacity of 120 gallons, it is ideal for smaller households or spaces where water heating needs are moderate. The HW-120M includes features such as an LED display for easy temperature monitoring and an integrated safety system that prevents overheating.

All these models utilize advanced technologies such as electronic ignition and enhanced insulation materials, contributing to a reduction in energy consumption and maintenance needs. The combination of these features makes A.O. Smith appliances a smart choice for consumers looking for efficiency, reliability, and performance. With a strong commitment to craftsmanship and innovation, A.O. Smith continues to set the standard in water heater technology, ensuring customers enjoy reliable hot water access while promoting energy efficiency.
Top Page Image Contents