Boiler Manual - Weil-McLain

GV90+ gas-fired water boiler — Boiler ManualTroubleshooting (continued)CHART 4PRESS SWITCH & POWER lights flashingElectrical shock hazard — Wherever you see TURN OFF POWER, follow the instructions. Failure to followinstructions could result in severe personal injury, death or substantial property damage.• Reset boiler control by turning off power at service switch orturning down thermostat for at least 45 seconds.• Thermostat should call for heat and appropriate zone valvesopen.Does blower motor operate?NoYesIs blower wheel turning at speed of blower motor?NoYes• Remove BLOWER plug (Figure 93, page 78, Item 3) fromplug receptacle of IBC.• Place voltmeter leads across the 120 VAC N and 120 VAC Hpins of the BLOWER receptacle.Does the voltmeter indicate 120 VAC?NoYes• TURN OFF POWER atservice switch.• Properly position blowerwheel on blower motorshaft and tighten set screw.(Or replace blower housingassembly.)• Retest.• Wait 5 minutes.Is purge light flashing?No Yes• TURN OFF POWER at service switch.Does blower wheel turn freely by hand?NoYes• Boiler should be in normal operating sequence(Figure 75, page 65).• Observe operation until thermostat is satisfiedand blower has completed its postpurgecycle.• Properly position blowerwheel on blower motor shaftand tighten set screw. (Orreplace blower housingassembly.)• Retest.• Replace blower motor.(Also check blowerhousing assembly.Replace if necessary.)• Retest.• Check Is blower condensate wheel turning trap. at speed of blower motor?Is there condensate present?NoYesNoYes• Remove one of the red wires connected to the pressureswitch.• Check continuity across the switch terminals.Does the ohmmeter indicate the switch is closed?NoYesAre vent or combustion airpassages blocked?NoYes• Drain condensate.• Retest.• Replace IBC.• Retest.• Check air pressure switch per page 75.• Replace if necessary.• Retest.• Clear passages and recycle boiler.• Recheck boiler operation.84Part number 550-142-054/1211