A.O. Smith HW-120M, 225M, 200M, 160M Circulating Pump, Tank Temperature Control, Safety Flow Switch

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4.Discontinues ignition spark when the pilot flame is established. The S-8600 control used on propane gas models provides safety lockout if the pilot fails to ignite within the pilot flame establishing period. The S-8600 control used on natural gas models continues trial for ignition until pilot flame is established.

5.After proof-of-pilot flame, opens the main valve.

6.On a power loss, shuts the heater down. When power is restored it will begin a new ignition cycle.

7.On a loss of flame, shuts off main gas and starts trial for pilot ignition.

INTERMITTENT IGNITION CONTROL MODULE (I.I.D.)

FIGURE 3

CIRCULATING PUMP

Constant circulating pump operation of the heater voids the warranty. Constant water flow through the unit will “wash” away the copper’s natural protective coating. This is called velocity erosion. This erosion is not as great a problem when intermittent circulating operation is used per the recommended installation procedure. Constant circulation of water between the storage tank and the building is permissible as long as the water does not constantly flow through the heater.

Only all bronze circulators are used with commercial water heaters.

Although circulators are oiled and operated by the manufacturer, THEY MUST BE OILED AGAIN BEFORE OPERATED. Oil the three oil cups (2 on the motor, 1 on the pump) as instructed by manufacturer. See fig. 4.

Thereafter, lubricate the three oil cups at least once every 4 months.

TYPICAL CIRCULATING PUMP

FIGURE 4

Use 2 or 3 teaspoonsful in bearing oil cups, and 10 or 12 drops in the motor oil cups. Use no. 20 non-detergent motor oil.

Follow the same oiling procedure if a replacement circulator is installed into the system.

TANK TEMPERATURE CONTROL

(Not Supplied)

DANGER

USE ANTI-SCALD VALVE(S) in the hot water system to reduce the risks of scalds at points of use such as lavatories, sinks and bathing facilities.

The tank temperature control is located in the lower portion of the hot water storage tank, see PIPING DIAGRAMS. It is the primary operating control of the system and regulates the water temperature in the tank.

The storage tank thermostat should have contact ratings that exceed the maximum electrical requirements of the system. Typically, the thermostat should have motor full load and locked rotor current ratings which exceed the total amount of current required to drive the pump(s) controlled by the thermostat.

The thermostat should have a temperature range of 1000F (37.7°C) to 1800F (82.2°C) or more. The preferred initial setting for the storage tank thermostat is 1200F (48.8°C). However, for normal use, the thermostat should be adjusted to the lowest setting which produces an acceptable hot water supply temperature. This will always give the most energy efficient operation. Do not adjust the thermostat to achieve a storage temperature of 190oF (87.7°C) or above. This action may cause the automatic gas shutoff control to activate shutting down the heater.

Intermittent ignition device and circulator start and stop simultaneously as the tank thermostat contacts open and close. This basic action, water flowing whenever the burner operates, must not be altered.

SAFETY FLOW SWITCH

(Not Supplied)

The safety flow switch is a safety device installed at the water outlet of the unit to prevent main burner operation in the event of inadequate water flow through the unit.

An accessory package A.O.S. No. 211480 containing a safety flow switch is available for this application.

This switch may be mounted in a horizontal pipe line or a vertical pipe line with upward water flow. Do not install the switch where the water flow is downward.

For proper performance mount the switch in a section of pipe where there is a straight run of at least 5 pipe diameters on each side of the flow switch (i.e. do not locate adjacent to valves, elbows, orifices, etc.).

The flow switch shall be mounted in a standard 1" x 1" x 1" tee for a 1" pipe application. For larger pipe sizes use a reducing tee in order to keep the switch as close to the pipe as possible. Install the flow switch in the branch (top) opening of the reducing tee and provide adequate paddle length in the flow stream. For example in a 2" pipe installation use a 2" x 2" x 1" reducing tee. For 1", 2" or 3" pipe use the paddle segments as supplied. For other pipe sizes (i.e. 1 1/4", 1 1/2", and 2 1/2") trim the paddle to the proper pipe size, see fig. 5. If a standard tee is used, install a face or hex bushing in the top opening. The paddle must be adjusted or trimmed to the size of the pipe in which it will be installed.

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Contents Models HW-120M, 160M, 200M, 225M Commercial GAS Copper Heat Exchanger Water HeaterROUGH-IN-DIMENSIONS Heater Performance DataTable of Contents General Safety InformationForeword 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 HeaterCheckout Removing SilicateSystem 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.
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