My forced air Gas heater makes a high-pitched whining noise but I'm
pretty sure that it's NOT the blower! If anyone has heating a/c
savvy, please read on.

We are in a house in Chandler, AZ, that is about 4 years old. It has
forced air gas heating. I hear that it's been done cheaply: both the
heater and air conditioner are located in the attic (the a/c
compressors are outside, the blower etc. are in the attic). People
say this is a bad design but cheaper for builders, so we're stuck with
it.

We bought the house in during the summer, so we tested the a/c and it
works flawlessly. I also tested briefly the heater enough to notice
that it worked, but I was so excited looking around our potential new
dream home I didn't notice the high pitched squeal it makes.

So around November, when you have to start using the heater in this
part of Arizona, I switch the thermostat over to heat and am appalled
when I hear this high pitch whining noise that appeared to coincide
with the heater. I figured, no problem, it's probably an unlucky
small vent in a duct that's making this noise, and I'll just find it
and go over it with duct tape. But then I notice that it doesn't
coincide with when the blower runs.

Here's its behavior: when the heater lights up to warm the air BEFORE
the blower starts, the whine begins. It continues while the blower is
blowing, but then about 2 minutes before the blower stops it stops. I
assume this is the same time the fire goes out and it stops actively
heating while the blower continues to blow over the still hot metal
parts.

Does anyone have any idea what is doing this? I could swear it seems
to be coming not from the heater itself but from some ductwork about
20 feet away in the attic (inaccessible to me), and this makes no
sense to me because as I said, it doesn't start and stop with the
blower, so I don't think it's some kind of air movement noise. (I
could be mistaken. In the small attic trying to locate the source of
the whine is like trying to find a cricket--I can't really tell where
its coming from.)

Any ideas?

The high-pitched whining you hear is almost certainly from the exhaust
fan.

Your furnace has two fans -- a small exhaust fan to make sure there's a
draft up the chimney to exhaust the combustion gases, and a large
blower fan to blow the air throughout the house. The running of the
exhaust fan coincides with when the gas is burning, which is what you
described.

It sounds like you've got a failed bearing in the exhaust fan, and it's
probably eventually going to fail completely. Ours took at least a
year to completely fail after the first time we heard it making bad
noises.

If you've got a service plan on the furnace, you can ask them to
replace the exhaust fan before it dies completely, but they may say no
(they did when my exhaust fan was dying and I asked them to replace
it). In that case, you'll have to pay them to replace it early, or
wait until it fails, in which case you'll have some period of time with
no heat while waiting for them to come replace it (and perhaps a longer
time while waiting for them to order the correct fan for your furnace,
which is also what happened to us).

Obviously, if you don't have a service plan on the furnace, then
you'll have to pay for replacing the fan whether you do it now or when
it fails completely, so you'll probably want to do it now for peace of
mind.

I'm including your whole article below, because your initial posting
had a typo in the Newsgroups line so it didn't actually appear in
alt.home.repair....

N Harrison writes:
My forced air Gas heater makes a high-pitched whining noise but I'm
pretty sure that it's NOT the blower! If anyone has heating a/c
savvy, please read on.

We are in a house in Chandler, AZ, that is about 4 years old. It has
forced air gas heating. I hear that it's been done cheaply: both the
heater and air conditioner are located in the attic (the a/c
compressors are outside, the blower etc. are in the attic). People
say this is a bad design but cheaper for builders, so we're stuck with
it.

We bought the house in during the summer, so we tested the a/c and it
works flawlessly. I also tested briefly the heater enough to notice
that it worked, but I was so excited looking around our potential new
dream home I didn't notice the high pitched squeal it makes.

So around November, when you have to start using the heater in this
part of Arizona, I switch the thermostat over to heat and am appalled
when I hear this high pitch whining noise that appeared to coincide
with the heater. I figured, no problem, it's probably an unlucky
small vent in a duct that's making this noise, and I'll just find it
and go over it with duct tape. But then I notice that it doesn't
coincide with when the blower runs.

Here's its behavior: when the heater lights up to warm the air BEFORE
the blower starts, the whine begins. It continues while the blower is
blowing, but then about 2 minutes before the blower stops it stops. I
assume this is the same time the fire goes out and it stops actively
heating while the blower continues to blow over the still hot metal
parts.

Does anyone have any idea what is doing this? I could swear it seems
to be coming not from the heater itself but from some ductwork about
20 feet away in the attic (inaccessible to me), and this makes no
sense to me because as I said, it doesn't start and stop with the
blower, so I don't think it's some kind of air movement noise. (I
could be mistaken. In the small attic trying to locate the source of
the whine is like trying to find a cricket--I can't really tell where
its coming from.)

Any ideas?

Thanks for all the advice. I found what I think is the inducer fan
after opening up my Carrier WeatherMaker 8000 (about 4 years old) and
oiled it with wd40 where I could reach, but it still makes the noise.
Perhaps it is the bad bearings Jonathan Kamens mentions.

BTW, I called Carrier and there is absolutely no technical help of any
kind offered. I can understand that with something so potentially
dangerous they don't dare give out advice to consumers, but I'm
spoiled by computer and software vendors who at least will look up the
symptoms and tell you what they know about a model/version. Carrier
offers nothing but "here's someone to call in your area."

writes:
Thanks for all the advice. I found what I think is the inducer fan
after opening up my Carrier WeatherMaker 8000 (about 4 years old) and
oiled it with wd40 where I could reach, but it still makes the noise.
Perhaps it is the bad bearings Jonathan Kamens mentions.

Several comments:

1) I believe that the lubricated parts (if any) of most fans for this
type of application are sealed such that lubricating the unsealed
portion won't help.

2) If, indeed, the unsealed portion of the fan was previously oiled or
greased, then the WD40 you added will probably break down that
oil/grease, thus making the problem worse.

3) WD40 is flammable.

4) I believe that the air which passes through this fan is rather hot.

BTW, I called Carrier and there is absolutely no technical help of any
kind offered. I can understand that with something so potentially
dangerous they don't dare give out advice to consumers,

Yes, indeed. Your attempt to fix the problem yourself may have made
it worse and/or caused a dangerous situation. I suggest you pay a
professional for a service call.

Did that explain the flames shooting out of the side of his house? I thought
that was the special effects crew from Inferno?

--

Christopher A. Young
Jesus: The Reason for the Season
www.lds.org
www.mormons.com


"Jonathan Kamens" wrote in message
...
writes:

2) If, indeed, the unsealed portion of the fan was previously oiled or
greased, then the WD40 you added will probably break down that
oil/grease, thus making the problem worse.

3) WD40 is flammable.

4) I believe that the air which passes through this fan is rather hot.

As others have noted, it is likely the induced draft fan motor making
the noise. I had a similar problem, to which I'll share the solution.

The draft fan motor on our furnace had little oil ducts at the top to
allow a light oil to drip onto the bushing. I called a gas appliance
place to ask about a proper lube, and he told me that "3 in 1" sewing
machine oil was the proper lubricant. I oiled the motor twice in a
couple of weeks, and the squeal went away, never to return for the rest
of the time we owned the house, a total of 10 years. I lubed the motor
occasionally, when I remembered, but it was never on a regular
schedule...probably would have been good to oil it twice a year.

Hope this helps!

Gerard


My forced air Gas heater makes a high-pitched whining noise but I'm
pretty sure that it's NOT the blower! If anyone has heating a/c
savvy, please read on.

We are in a house in Chandler, AZ, that is about 4 years old. It has
forced air gas heating. I hear that it's been done cheaply: both the
heater and air conditioner are located in the attic (the a/c
compressors are outside, the blower etc. are in the attic). People
say this is a bad design but cheaper for builders, so we're stuck with
it.

We bought the house in during the summer, so we tested the a/c and it
works flawlessly. I also tested briefly the heater enough to notice
that it worked, but I was so excited looking around our potential new
dream home I didn't notice the high pitched squeal it makes.

So around November, when you have to start using the heater in this
part of Arizona, I switch the thermostat over to heat and am appalled
when I hear this high pitch whining noise that appeared to coincide
with the heater. I figured, no problem, it's probably an unlucky
small vent in a duct that's making this noise, and I'll just find it
and go over it with duct tape. But then I notice that it doesn't
coincide with when the blower runs.

Here's its behavior: when the heater lights up to warm the air BEFORE
the blower starts, the whine begins. It continues while the blower is
blowing, but then about 2 minutes before the blower stops it stops. I
assume this is the same time the fire goes out and it stops actively
heating while the blower continues to blow over the still hot metal
parts.

Does anyone have any idea what is doing this? I could swear it seems
to be coming not from the heater itself but from some ductwork about
20 feet away in the attic (inaccessible to me), and this makes no
sense to me because as I said, it doesn't start and stop with the
blower, so I don't think it's some kind of air movement noise. (I
could be mistaken. In the small attic trying to locate the source of
the whine is like trying to find a cricket--I can't really tell where
its coming from.)

Any ideas?


--
Gerard's Automobile Book, Video, and DVD Store
http://www.bob2000.com/booksvids.html
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