Hi:
I have an older Lennox G803-120-1 furnace that's about 38 years old. Everything is still fine - fan, motors, pilots, burners are all running smoothly. One problem I have since two years ago is that during the Spring season, there is an occasional loud rattling/grinding mechanical noise that coming from the chimney of the furnace. The noise is not coming from the actual furnace but up in the chimney/ This happens when the furnace isn't even running. I have even taken this video to the Lennox distribution warehouse/office and nobody there knows where the periodic noise is coming from. Someone there suggested maybe it's coming from a bird, but as you can hear this is a mechanical noise. I have tried disconnecting the humidifier off but the noise still comes and goes. It would go away for 1 year, several months or weeks and then coming back again. Funny thing is I have never heard the noise during winter when the furnace is on most of the time. I also noticed that when the noise say comes in for 4 to 5 reps, it would go away if I turn up the thermostat by 1 degree to activate the furnace. Heat comes on and the noise goes away. The noise is not constant. It would just comes and goes for 4 - 5 rep in between days, weeks, months. This started in 2019 periodically, none in 2020 and is now just happening again. Any idea? please help. the first noise comes on at 25 seconds of the video then at 50 seconds.
https://photos.app.goo.gl/k2dUm7wFGLR21bxM7
I have an older Lennox G803-120-1 furnace that's about 38 years old. Everything is still fine - fan, motors, pilots, burners are all running smoothly. One problem I have since two years ago is that during the Spring season, there is an occasional loud rattling/grinding mechanical noise that coming from the chimney of the furnace. The noise is not coming from the actual furnace but up in the chimney/ This happens when the furnace isn't even running. I have even taken this video to the Lennox distribution warehouse/office and nobody there knows where the periodic noise is coming from. Someone there suggested maybe it's coming from a bird, but as you can hear this is a mechanical noise. I have tried disconnecting the humidifier off but the noise still comes and goes. It would go away for 1 year, several months or weeks and then coming back again. Funny thing is I have never heard the noise during winter when the furnace is on most of the time. I also noticed that when the noise say comes in for 4 to 5 reps, it would go away if I turn up the thermostat by 1 degree to activate the furnace. Heat comes on and the noise goes away. The noise is not constant. It would just comes and goes for 4 - 5 rep in between days, weeks, months. This started in 2019 periodically, none in 2020 and is now just happening again. Any idea? please help. the first noise comes on at 25 seconds of the video then at 50 seconds.
https://photos.app.goo.gl/k2dUm7wFGLR21bxM7