mebaskin
Dec 31, 2006, 04:14 PM
Hello
I own a vintage Bryant #394GAD036100 furnace that is working just fine accept for one little problem. The unit cycles and maintains the desired temp setpoint (heating mode) but after the main recirc blower shuts off it restarts momentarily one time approx 2 sec later,
And again approx 2 sec later.
I currently have an electrostatic furnace filter and a humidifier(media wheel type external) hooked up to the auxiliary pilot contacts. Originally convinced that I was dealing with a coasting blower wheel back EMF issue,I applied 130v metal oxide varistors at various places about the control circuit board(across relay contacts,txfmr etc.),still no relief.I then disconnected the aux circuit loads (humidifier and EP filter) same problem.
I am about ready to drag out my oscilloscope and monitor the PCB for any stray spike activity. I believe that the onboard operational amplifier is simply being used as post gas valve shutoff time delay.
Does any of this make any sense,and has anyone else ever experienced this problem previously?
Thank you and I look forward to any suggestions or help. If I had a schematic on the PCB I could fix it in a snap.
Mark
I own a vintage Bryant #394GAD036100 furnace that is working just fine accept for one little problem. The unit cycles and maintains the desired temp setpoint (heating mode) but after the main recirc blower shuts off it restarts momentarily one time approx 2 sec later,
And again approx 2 sec later.
I currently have an electrostatic furnace filter and a humidifier(media wheel type external) hooked up to the auxiliary pilot contacts. Originally convinced that I was dealing with a coasting blower wheel back EMF issue,I applied 130v metal oxide varistors at various places about the control circuit board(across relay contacts,txfmr etc.),still no relief.I then disconnected the aux circuit loads (humidifier and EP filter) same problem.
I am about ready to drag out my oscilloscope and monitor the PCB for any stray spike activity. I believe that the onboard operational amplifier is simply being used as post gas valve shutoff time delay.
Does any of this make any sense,and has anyone else ever experienced this problem previously?
Thank you and I look forward to any suggestions or help. If I had a schematic on the PCB I could fix it in a snap.
Mark