Coleman Rattle After Gas Ignition

[sameyers]

I could really use some help on this one... After my Coleman furnace in my 87 mobile home lights off the gas, my heater makes a rattling sound throughout the whole burn time of the heating cycle after the gas lights off and stops when the burner stops and while the blower motor continues to run for the minute or so. I have verified that the sound seems to be coming from the top to where the exhaust connects to the unit. With a mirror and flashlight (obviously not sticking my head directly above it) I have seen something moving around while the unit is in operation in the exhaust pipe when I am on the top of the roof looking down the exhaust.

I have contacted Coleman directly before I found this great site and they gave me an idea and wanted to run it past you for further help. The Coleman rep said that it is a shutter that is directly in the exhaust path and loosens up over time and starts to rattle. Is this correct? They said that it might be loose rivets holding the shutter in place that might be the culprit.

I have slid up the outer exhaust pipe on the unit but am having trouble getting the inner pipe to slide up so I can access the shutter. Any ideas on how to do this? I figured that if I can get to it, I have the skills to fix it or replace it.

I also wanted to say thanks in advance and I would be humbly grateful for any advice on how to proceed on this.

[Robert]

Hi,

You're very welcome and thanks for the kind words and compliments from myself and Mark (owner of website).


What he referred to as a shutter I'm guessing is what is called a Flue Restrictor . It is to restrict combustion gases exiting furnace with residual heat still in them and keep them inside heat exchanger a little longer to remove as much heat as possible.

Not all furnaces have them, but several do.

They are held in place by a stainless steel rivet which in time can and does sometimes come loose.

If it becomes loose and the restrictor rattles, a second stainless steel rivet or screw may need to be added.

This must be done without changing the design of the restrictor opening or closing.


Did you try gently twisting the inner flue pipe to get it to slide upward ?


Could be some rust holding it in place.


Take care and best wishes,
Robert