Home  Test

1 Blink followed by 2 Sec. Pause- 1 Hr lockout
2 Blinks followed by 2 Sec. Pause- Pressure Switch is Open
3 Blinks followed by 2 Sec. Pause- Limit Switch is Open
4 Blinks followed by 2 Sec. Pause- Pressure Switch is Closed
5 Twinning fault
 
Auxiliary limit switch: located on warm air blower housing n monitor return air To  
Draft safeguard switch: NC, open when detect flu gas leaking  
Manifold pressure: 11" of a manometer, connecting to gas valve to check  
Limit switch: NC. When furnace is overheated [200_250oF], it open to and close main valve gas
Helical bimetal: positioned next to the heat exchanger control Limit sw and fan sw  
Flame proving devices: Thermocouple[15_30 mV],, thermopile, bimetallic strip, liquid-filled remote bulb.
Igniters: Intermittent pilot (IP), Diewct-spark ignition (DSI), Hot surface ignition(HSI)
Gas Pressure : 3.5 WC
Pressure SW: NO, 24v terminals continuity when reduced draft fan working