PaPaPeng wrote:
On Sat, 11 Mar 2006 12:35:55 GMT, "Paul Isaacs"
wrote:


I have an old Singer furnace, model GL1406, which I'm told is over 30 years
old (I've owned the house for 23 years). Except for two recent minor
electrical problems which cut off power to the blower motor, the unit has
been working fine. I have been told, however, that the blower bearings are
not in great shape and I should get a new furnace and it would be a lot more
efficient. Our gas bills, in NYC, have been very high lately, but is it
worth $4500 for a new Carrier 80% efficient furnace + $800 for a "by-pass
humidifier" to gain that efficiency? Prices include installation and
readapting ductwork, plumbing and electric. Which other brands should I
consider?




Your furnace works fine. The only critical factor to merit a furnace
replacement is if the heat exchanger is cracked and lets in toxic
combusted air into the house air circulation. Only then is it
mandatory and more economical to replace the furnace than to replace
the heat exchanger.

My Inter City gas furnace is 30 years old and looks as new as the day
it was installed. I had been coughing last season whenever my furnace
fired up. I asked the gas company for a FREE furnace inspection.
Your gas company should have a similar service. The technician gave
it a OK but said that the heat exchanger was already getting old.
Call for another inspection in the future if I suspect anything. He
also noted that I had put the fan in backwards. It will work but
won't blow that efficiently. Its easy to take out the fan and turn it
around to rotate the correct direction.

I spent $350 to get the furnace ducts cleaned, the only time in 30
years, and my coughing fits stopped.

25 years ago I swapped the 1/3 HP furnace blower for a 1/2 HP one from
my table saw. (I upgraded the table saw to 1 HP.) That motor has
been humming without trouble up to today. When I did the swapping I
also took out the squirrel cage blower fan to clean it. Reassembled
the stuff and it worked fine. After about a year's running the
furnace had an annoying thunk everytime the fan started or stopped.
So I tightened the fan belt, oiled the bearings and it will work fine.

This went on for 4 years until the thunks were rather disturbing and I
decided to take the fan out to clean it as well as check the
mechanism. The noise must be related to the fan as that was the only
moving part. The motor was fine. I found the bronze sleeve bearings
ovalled and the fan shaft worn and gouged quite deeply. I had
overtightened the fan belt. The tension wore into the bronze
bearings. Adding lube oil retained the metal filings to create an
abrasive slurry that gouged into the steel fan shaft.

The bearings are available from any appliance repair supplies shop.
They are meant to run without lubrication. Frankly the heat in the fan
chamber would distill off the light oil faction and leave a gummy
residue that is no good for lubrication. My 1/2 HP motor would have
overcome any frictional resistance without trouble where a 1/3 HP
motor might have overload burn out. The shaft is just be a 3/4 inch
diameter steel rod. The repairs were quite simple and can be managed
by anyone who is not all thumbs.

My advice for you is to get your gas company to give your furance an
inspection. He does not do repairs and has the obligation to give a
professional opinion on the safety aspects of your furnace. He also
has the obligation to report any serious furnace safety problems.
Besides gassing yourself your house can catch fire and burn down the
neighborhood in the process.

Take apart the blower fan assembly anyway and do a thorough clean-up
of that chamber. Obviously you do this only in the warmer months when
you no longer need the furnace running. You will be amazed at the
gunk and dust coats that had accumulated. Vacuum first. For stubborn
oilsoaked dust use varsol to wipe them off. A wet cloth and maybe some
soap should remove the rest. Then leave the chamber as clean bare
metal. Any oil or other coating will just attract dust which will be
baked onto the chamber walls. Much of the respiratory problems during
winter likely arise from the dust and gunk buildup lurking inside trhe
furnace.

The fan motor bearings are meant to run dry. My fan motor has been
running for more than a decade now without trouble. I check and clean
the fan chamber every three years or so. Do not add lube oil (ref.
abrasive slurry above). Set the hinged motor such that the standoff
screw will just hold the motor against the stop. The fan belt tension
should be from the weight of the motor, not by tightening the
standoff screw.
Hmmm,
Your old furnace may be working OK but it is of old technology with LOW
efficiency! Would you drive a car of '60s? Gas guzzling, polluter?