A.O. Smith 100 Power Vent DV Series 120, 317443-000 Blower Prover Switch, Blocked Exhaust Switch

Page 33

CONTROLS AND SWITCHES

This model is provided with three 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.

Figure 33.

BLOWER PROVER SWITCH

(SEE FIGURE 33)

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.

BLOCKED EXHAUST SWITCH

(SEE FIGURE 33)

The Blocked Exhaust 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. Also verify that the vent length does not exceed the maximum allowed as shown in the Vent Section of this manual.

BLOCKED INTAKE SWITCH

(SEE FIGURE 33)

The Blocked Intake Switch is set up to shut the unit off when a build-up of negative pressure in the intake air 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 PVC pipe connected to the inlet of the blower. When this switch prevents the unit from igniting, most likely the intake is blocked. Verify that the screen on the intake air connection (conventional vent), the intake air pipe and termination (direct vent installations) are free of obstructions that may prevent air from entering the unit. Insure the screen on intake air connection has been removed on direct vent installations, see Figure 15. Also verify the intake air pipe length does not exceed the maximum allowed as shown in the Vent Section of this manual.

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.

HOT SURFACE IGNITER

The Hot Surface Igniter is a device that ignites the main burner by high temperature (>1800°F or >982°C). When 120VAC is applied to the igniter, sufficient heat is generated to ignite the main burner.

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Contents Whenever maintenance adjustment or service is required Printed317443-000 Table of contents Approvals Safe installation, use and serviceGeneral safety information Precautions Hydrogen Gas FlammableGrounding Instructions General safety information Fire or Explosion Hazard Introduction Preparing For The InstallationAbbreviations Used QualificationsReplacement Parts and Deliming Products Features and componentsRough in Dimensions Installation considerationRough-In-Dimensions Recovery capacity based on 96% thermal efficiencyLocating The Water Heater Property Damage HazardCombustion AIR and Ventilation Insulation BlanketsUnconfined Space Fresh Air Openings For Confined Spaces Confined SpaceOutdoor Air Through Two Openings Outdoor Air Through One OpeningAir From Other Indoor Spaces Outdoor Air Through Two Horizontal DuctsPower Supply Installing the new water heaterChemical Vapor Corrosion Water PipingMixing Valves Dishwashing MachinesSpace heating and potable water system Closed Water Systems Thermal ExpansionValve and Pipe Insulation if supplied Valve Discharge Pipe Requirements Temperature-Pressure Relief ValveCondensate Piping Gas pipingFilling the Water Heater High Altitude Installations Sediment TrapsVenting Vent Pipe TerminationPlanning the Vent System Vent Terminal INSTALLATION, Sidewall Installation of Vent SystemInstallation of Carbon Monoxide Detectors Installation Requirements Commonwealth of MassachusettsApproved Carbon Monoxide Detectors SignagePower Vent Termination Clearances Sidewall Power VentDirect Vent Termination Clearances Sidewall Direct VentSequence of INSTALLATIONS, a Installation SequenceVent Termination a Direct Vent terminal installation Vent Terminals Supplied with Heater Must be UsedFlat Roof Installation Safety Considerations Concentric vent installationKIT Components Description QtyConcentric Termination Flat Roof Clearance MULTI-CONCENTRIC Vent Terminations Direct vent diagram Vent Pipe Preparation Step E Step BStep F Step GBlocked Exhaust Switch Blower Prover SwitchBlocked Intake Switch ON/OFF SwitchPower Vent Wiring Schematic Figure Do not try to light the burner by hand What to do if YOU Smell GASDo not TRY to Light the Burner by Hand HI Limit Switch ECO Temperature regulationControl system operation OverviewControl System Navigation Status Icons Icon DescriptionControl System Menus Operating StatesTemperatures Operating Set Point And Differential Adjustment User Settings & Control System MenusHeater Status TemperaturesECO Contact , Blocked Inlet PS , Blocked Outlet PS , Blower Blower Low On , Blower High On displays whetherHeater Information Display SettingsFault History Current FaultFault Occurrence Restore Factory DefaultsService Contact Information Service Contact InformationFor your information Start UP ConditionsOperational Conditions Temperature-Pressure Relief Valve Operation Periodic maintenanceVenting System Inspection Anode ROD InspectionService To drain the water heater storage tankTo Flush the Water Heater Storage Tank Temperature-Pressure Relief Valve Test MaintenanceLeakage checkpoints Installation Checklist TroubleshootingYES no Sequence Of Operation Flow ChartFault And Alert Conditions Operational ProblemsDiagnostic Checks Resetting Control System Lock OutsAC Reversed Fault And Alert MessagesBlower Prover Failure Page Page Page Fill in Warranty and Keep for Future Reference Limited Warranty
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