Boiler Manual - Weil-McLain
Boiler Manual - Weil-McLain
Boiler Manual - Weil-McLain
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GV90+ gas-fired water boiler — <strong>Boiler</strong> <strong>Manual</strong>Troubleshooting (continued)CHART 3LIMIT & 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.• This is a LOCKOUT condition. The return water temperaturesensor has signaled a temperature higher than 240 °F, buttheboiler limit circuit is closed (indicating that the limit control circuitdid not catch the over-temperature condition). This is probablyan indication of a failure of the boiler limit control and possiblythe block temperature switch as well.• TURN OFF POWER to boiler at 120 VAC service switch.• Remove CONTROL CIRCUIT plug from IBC receptacle (Figure93, page 78, Item 5).• Remove a wire from one of the limit control spade connectors.• Connect an ohmmeter across the left and right pins on thecenter row of the limit circuit harness.Does the ohmmeter indicate a shorted wire harness (zero ohms)?YesNo• Replace control wiring harness.• Retest.• Replace water temp sensor.• Retest.• Reconnect CONTROL CIRCUIT plug to IBC.• Remove WATER TEMP SENSOR plug from IBC receptacle(Figure 93, page 78, Item 6).• Connect an ohmmeter across the plug pins to check the sensorresistance.Does the ohmmeter indicate a shorted sensor (zero ohms)?YesNoYesIs boiler hot?No• Close the external manual gas valve.• Remove one wire from the limit control spaceconnector.• Set a thermostat to call for heat. Then turn onpower to the boiler at the 120 VAC service switch.• The boiler system circulator should come on andthe IBC should try to cycle the boiler.• Allow the boiler circulator to run to cool off boilerand system water.• After the boiler and system water have cooled,turn off power at the 120 VAC service switch andopen the external manual gas valve.• Set limit control knob to its minimum setting. Replace wire tolimit control spade connector.• Set a thermostat to call for heat.• Turn on power at 120 VAC service switch.• IBC should cycle boiler on and begin heating.• The limit control should shut off the gas valve when thetemperature at the boiler pressure/temperature gauge hasreached no more than about 20 °F higher than the limitswitch setting.Does limit control shut off gas correctly?YesNo• Replace IBC.• Retest.• Replace limit control andblock temperature switch.• Retest.Part number 550-142-054/1211 83