"Stormin Mormon" wrote in message ...
From your descrip, it sounds like it might be a booster fan to move the flue
gasses up the pipe. Sometimes those have an oil hole on each end of the
motor. Couple drops of SAE 20 or SAE 30 oil might quiet things down.
I couldn't really figure out what it was exactly. My motivation for
figuring things out is so that I can have a constructive brainstorm
with a gas contractor. This way I feel a little in control and would
prevent him from spending time and replace unnecessary parts.
Not being a gas specialist, I only looked and reasoned, to the best of
my abilities, and I knew it had to be a 3rd moving part. Not the main
fan, not the blower, something else. The loud humming/buzzing was
coming from higher up I thought.
So, ok, in the middle of a snow storm, the furnace stopped working.
The gas guy took a while, but together, I was able to work through
things logically. He started to take things apart, and told me it
looks like the large main fan motor. I told him that when I put the
thermostat's switch fan position to 'on' instead of 'auto', the fan
sounds like it's moving air quite nicely. He measured the amperage
how much the motor was drawing, looked normal.
After he took the front of the furnace apart, and started the motor,
he now thought the motor was running well, and the noise was indeed
coming from elsewhere.
Then, bingo. Right outside the house there is a little box with
'power vent' written on it. It's built into a small metal cage, and
mounted on the outside of the house. In it, there is a motor that
sucks the air out, and assists in flowing the exhaust out. There is a
small solid line that runs inside to another small box with a sensor
in it. If the sensor says that the venting is working well, it tells
the furnace it's good to go.
The motor is stuck and is making a humming and buzzing kind of noise.
Needless to say, this box being outside results in a shorter lifespan
than if this fan had been inside just before the pipe exits the house.
By the looks of the manuals of Lennox, it looks like this suction
exhaust thingy (power vent thing) is optional, because the other fan
normally blows the air out of the furnace. The exhaust is on the side
of the house. The exhaust from furnace to outside is about 6 or 7
feet.
Now the fun part. This part is not in stock and needs to be ordered
from the manufacturer. The number is SWG-4HD. I have no idea what
this thing is going to cost me. If anyone could tell me, that would
help.
Luckily, I have a gas fireplace, and it keeps half the house
relatively warm. The cat looks very comfortable, I think I might join
him ;-)
Tomorrow I'll find out more about this mistery part. Stay tuned.
Thanks to all giving me feedback btw. I'm not taking any chances and
will not risk blowing myself up, and am leaving the real work to a
professional ;-)
Some years ago, I had a blower fan in my trailer furnace start to squack.
Really enough to drive me out of the house. I took the blower cage out, and
found that it had oil holes. Put in a couple drops of oil, and it never
bothered me again.
--
Christopher A. Young
Jesus: The Reason for the Season
www.lds.org
www.mormons.com
wrote in message
om...
Greetings,
I have a Lennox 80MGF furnace that is making loud noises from time to
time.
I first thought that the blower's ball bearings or something was bad
and that the motor action is what was producing the loud noises.
The noise happens only sometimes and is rather loud.
After standing next to the furnace long enough for the sound to appear
again, as it's intermittent, I now think that the noise is coming from
a small box near the gas exhaust pipe near the wall where the pipe
exits through the wall from the basement to outside.
This little box looks has a flexible metal hose leading to the
furnace. It also has a solid hard small pipe line leading to the top
of the exhaust. I can't see where it exactly leads because it kind of
dissappears into the wall. The box is pretty much square and has a
small round thing on the side.
My ignorant mind is making the wild guess that this box takes samples
from the exhaust air, and determines that it does not like what it
smells, and is sounding an alarm.
I know I know, call in the gas guy. But I'd like to know a few things
before the gas guy starts telling me things.
If really needed, I could upload some digital pictures somewhere...