On Sun, 15 Aug 2004 02:53:24 GMT, Scott
wrote:


Hi, I was wondering if anyone had any ideas about how to reduce the
noise coming from my furnace. Usually there's some steady noise, making
it sound kind of like an old locomotive in the distance. Occasionally,
it sounds like it's banging around....


I had a similar problem way back that I caused by over tightening the
fan belt and I think compounded by adding grease to the bearings. My
diagnosis was that the grease dried up from the furnace burner's heat
and caused friction on the bearings. The dried grease and bearing
shavings created an abrasive slurry that wore further into the
bearings until it ovalled the shaft hole as well as gouged the shaft
itself. Thus the banging when the blower starts or stops plus the
other noises your furnace has when running.

The remedy will be to replace the fan shaft and the bearings, a fairly
easy job. Use the opportunity to clean the fan and the insides of
the furnace. Be careful of sharp metal edges. Manufacturers then
weren't that careful to remove the burrs.

The bearings are just plain bronze bearings meant to run without any
lubrication. A few drops of car engine oil initially perhaps to let
the shaft and bearings seat in but that's it. Of course when you
replace the parts make sure that the fan belt and motor/fan pulleys
are aligned. The belt tension should be provided by the weight of the
hinged mounted motor only.

Since that replacement my gas furnace has been running more than 10
years now without trouble