A.O. Smith BTH 300A, BTH 400A Vent Pipe Preparation, Controls and Switches, Blower Prover Switch

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VENT PIPE PREPARATION

1.INITIAL PREPARATION

A.Make sure the solvent cement you are planning to use is designed for the specific application you are attempting.

B.Know the physical and chemical characteristics and limitations of the PVC, PVC cellular core, ABS or CPVC piping materials that you are about to use.

C.Know the reputation of your pipe and cement manufacturer and their products.

D.Know your own qualifications or those of your contractor. The solvent welding technique of joining PVC, PVC cellular core, ABS or CPVC pipe is a specialized skill just as any other pipe fitting technique.

E.Closely supervise the installation and inspect the finished job before start-up.

F.Contact the manufacturer, supplier, or competent consulting agency if you have any questions about the application or installation of PVC, PVC cellular core, ABS or CPVC pipe.

G.Take the time and effort to do a professional job. Shortcuts will only cause you problems and delays in start-up. The majority of failures in these systems are the result of shortcuts and/or improper joining techniques.

2.SELECTION OF MATERIALS

PRIMER

It is recommended that Tetrahydrofuran (THF) be used to prepare the surfaces of pipe and fittings for solvent welding. Do not use water, rags, gasoline or any other substitutes for cleaning PVC cellular core, ABS or CPVC surfaces. A chemical cleaner such as MEK may be used.

CEMENT

The cement should be a bodied cement of approximately 500 to 1600 centipoise viscosity containing 10-20% (by weight) virgin PVC material solvated with tetrahydrofuran (THF). Small quantities of dimethyl formamide (DMF) may be included to act as a retarding agent to extend curing time. Select the proper cement; Schedule 40 cement should be used for Schedule 40 pipe. Never use all-purpose cements, commercial glues and adhesives or ABS cement to join PVC or CPVC pipe and fittings.

SAFETY PRECAUTION: PRIMERS AND CEMENTS ARE EXTREMELY FLAMMABLE AND MUST NOT BE STORED OR USED NEAR HEAT OR OPEN FLAME. ALSO, USE ONLY IN A WELL-VENTILATED AREA.

CONTROLS AND SWITCHES

The BTH-300 & 400 are equipped with four pressure switches. These switches are essential to the safe and proper operation of the unit. All switches are wired in series. The controller is set up to shut the unit down whenever there is a failure of any of the switches. It is important to understand the purpose of each switch.

BLOWER PROVER SWITCH

The Blower Prover Switch is provided on the heater to verify that the fan is operating. It is a positive pressure switch whose electrical contacts are normally open. When the fan increases the pressure in the burner, the pressure switch will allow the electrical contacts

to close. The pressure switch is connected to the burner tap by a piece of tygon tubing. This tubing must be connected in order for the switch to change the electrical contacts. The controller requires that the electrical contacts on this air flow switch be open before it will allow the blower to come on. See Figure 13.

BLOCKED OUTLET PROVER SWITCH

The Blocked Outlet Prover Switch is set up to shut the unit off when a build-up of positive pressure in the exhaust vent pipe occurs. This switch is a positive pressure switch that requires an increase in pressure to change the electrical contacts from normally closed to open. When this switch prevents the unit from igniting, most likely the exhaust is blocked by some means. Check to see if the condensate is allowed to flow freely from the exhaust elbow and for obstructions in the exhaust venting and exhaust vent terminal. See Figure 13.

BLOCKED INLET PROVER SWITCH

The Blocked Inlet Prover Switch is set up to shut the unit off when a build-up of negative pressure in the intake vent pipe occurs. This switch is a negative pressure switch that requires an increase in negative pressure to change the electrical contacts from normally closed to open. The switch is connected to the pressure tap on the flange connected to the inlet of the blower. When this switch prevents the unit from igniting, most likely the intake is blocked by some means. Check to see if there is no more than eighty (80) equivalent feet (24.8m) of four inch PVC vent pipe on the intake. Also verify that the intake and intake vent terminal is free of obstructions that may prevent air from entering the unit. See Figure 13.

LOW GAS PRESSURE SWITCH

The Low Gas Switch (LGS) is a single-pole, normally open pressure switch that will close its contacts when a rising pressure of 4.6 in. W.C. (1.25 Kpa) is encountered. The contacts will open when the pressure falls below the fixed set point of 4.6 in. W.C. (1.25 Kpa) The LGS monitors the gas supply pressure to the heater. If the gas supply falls below 4.6 in. W.C. (1.25 Kpa), the main burner is extinguished (if heater is running) or the heater will not start up.

NOTE: LOW GAS SWITCH IS LOCATED ON INLET SIDE OF GAS VALVE. See Figure 13.

FIGURE 13.

ON/OFF SWITCH

The ON/OFF Switch is a single-pole, single-throw rocker switch. This switch provides 120V from the line source to the heater.

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.

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Contents Cyclone XHE Model BTH 300A and 400A Foreword ROUGH-IN-DIMENSIONSGAS Valve Piping Features Table of ContentsHorizontal Sidewall Venting Vertical Rooftop Venting Quick Installation TipsHigh Limit Switch E.C.O Water Temperature Setpoint Adjustment ProcedureDishwashing Machine Requirement Circulating Pump Installation InstructionsRequired Ability Insulation BlanketsHard Water ClearancesUnconfined Space Confined SpaceCanadian Direct Vent US Direct VentCanadian Horizontal Vent US Horizontal VentVent Pipe Termination Direct Vent Terminal InstallationDirect Venting Vertical Vent Terminal Installation Installation SequenceVent Length Table Installation of Vent SystemBlower Prover Switch Controls and SwitchesBlocked Outlet Prover Switch Blocked Inlet Prover SwitchGAS Piping HOT Surface IgniterConnection 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 Operating Instructions Adjustment Procedure Initial START-UPPrior 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 RUNNoisy Burner Operation Replacement PartsGAS 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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