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Old 01-01-2010, 07:17 PM   #1
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What runs before furnace starts


the furnace is an interior upright furnace.

something turns on that makes a loud squeeky noise! this sound comes from lower half of furnace.

then after 30sec or so, the furnace lights up and some sort of blower/fan starts. the sound comes from upper half of furnace and below evaporative cooler.

I"m assuming the thing that makes the loud squeeky noise will break down soon. what is it?

I'd like to tackle it before it breaks down so i can quickly fix it and also have time to shop around and save money. (first and prolly only time to use smilies)


Last edited by rosco; 01-01-2010 at 07:20 PM.
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Old 01-01-2010, 07:49 PM   #2
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What runs before furnace starts


it sounds like probably a draft inducer fan. It is not uncommon to have one go bad.

what is the manufacturer and model of your furnace? Somebody can probably check to see if your unit has one.

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Old 01-02-2010, 11:07 PM   #3
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What runs before furnace starts


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it sounds like probably a draft inducer fan. It is not uncommon to have one go bad.

what is the manufacturer and model of your furnace? Somebody can probably check to see if your unit has one.
This is all the information i can find: carrier Weathermaker 8100TS interior HVAC unit? product: 58TUA100----12116; model 58TUA100-16; series 120; serial 3000A61374

yes, i'd like to find out what it is and if someone can help, i'd greatly appreciate it.
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Old 01-03-2010, 10:27 AM   #4
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What runs before furnace starts


from what I have found (not a lot) you have a draft inducer and I believe, as you open the front cover, it will be on the left upper corner of that opening. I saw a quick glimpse of one in a video from a guy that was having some other problems with his unit.

from what I could see it is most likely black and about 3 or 4 inches in diameter.

So, can you take off the front cover? If so, do that and set the thermostat so it will start (or have somebody else set the t-state so you can be at the unit when it starts).

Listen to the area the draft inducer is and see if that is it.

I found a video that shows a very good view of the draft inducer. This is an 8000 series but I believe it is the same basic configuration.

at exactly the 8 second mark on the video, he is pointing the camera right at the draft inducer

Last edited by nap; 01-03-2010 at 10:31 AM.
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Old 01-03-2010, 07:06 PM   #5
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What runs before furnace starts


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Originally Posted by nap View Post
from what I have found (not a lot) you have a draft inducer and I believe, as you open the front cover, it will be on the left upper corner of that opening. I saw a quick glimpse of one in a video from a guy that was having some other problems with his unit.

from what I could see it is most likely black and about 3 or 4 inches in diameter.

So, can you take off the front cover? If so, do that and set the thermostat so it will start (or have somebody else set the t-state so you can be at the unit when it starts).

Listen to the area the draft inducer is and see if that is it.

I found a video that shows a very good view of the draft inducer. This is an 8000 series but I believe it is the same basic configuration.

at exactly the 8 second mark on the video, he is pointing the camera right at the draft inducer
NAP,
Many thanks for following up. the "draft inducer" or black thing, is in the upper panel. the noise comes from the lower panel before the things in the upper panel start (draft inducer and gas blowers).
it is the fan that runs when the heat and AC are both turned off. the "fan" on the wall thermostat.
Would you know the name of this fan? and would you know if a novice could replace it? the squeek only happens when i run the thing labeled "fan" on the wall thermostat for a full day. if i turn the heater and fan off for ~30 min and then turn only the furnace back on, no squeek.

Thanks for the help!
Rosco
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Old 01-03-2010, 07:32 PM   #6
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What runs before furnace starts


well, that would just be known and the "fan" or "blower fan" or "blower".

It should not be running before your heat exchanger has heated up.

Quote:
something turns on that makes a loud squeeky noise! this sound comes from lower half of furnace.

then after 30sec or so, the furnace lights up and some sort of blower/fan starts
the order of operation should be:

draft inducer runs
burner fires
a bit later the blower runs

when the thermostat is satisfied, the burner and draft inducer will shut off and then a bit later, the blower will shut off.

You kind of lost me on the order of running on your furnace though. It doesn't make a lot of sense to me as you put things.


So, if we are happy that it is the blower, is the sound a metal scraping or more or a squeaky sound? I have had blowers that the mounts have deteriorated enough that the fan hit it's shroud, especially on start up.

or, the motor itself could be going bad. It won't save it forever but it might prolong it's death if the motor can be oiled. You will have to open up the housing and look at the motor and see if there is a place it can be oiled. They often have a little spring loaded lid where you would oil it. there is often one on each side of the motor.

be sure to turn the power off to the furnace when you are working on it so it does not start while you have you hands someplace that would not mesh well with the furnace running.

for the life of me I cannot find a picture of an oil port for a blower motor. Anyway, if you can oil it, you would use a light oil, like 10 weight.

here is a pic of a motor with just a small hole for oil, no spring loaded cap

while you are at it, check the inducer motor for the ability to be oiled as well.
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Old 01-03-2010, 09:32 PM   #7
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What runs before furnace starts


If the draft inducer is the black round wheel (shown at 8sec in video) this is not making the noise. the noise starts before that black wheen and a motor start. It is in the lower half of the unit, whereas the furnace flames the black wheel (and some sort of motor/blower behind the black wheel. it is behind the black wheel in the video). i think it is the fan that ciruculates air throughout the house.
i just pulled bottom panel off (where the noise comes from). there is a large squirrel cage with a motor in it. it is one of these two things. Is the blower and blower fan? or is it just a fan motor and fan squirrel cage?

draft inducer runs
burner fires
a bit later the blower runs
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Old 01-03-2010, 09:40 PM   #8
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What runs before furnace starts


it is the squirrel cage fan aka blower all the same thing, that I was speaking of possibly oiling.

your fan/blower is running before the furnace even fires?

the only other thing that would act before the draft inducer would be a power damper but that would only run long enough to open and then stop. A few seconds tops.

here is a drawing of a basic updraft furnace. Anything look familiar as to what is making the noise?

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Old 01-03-2010, 10:36 PM   #9
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What runs before furnace starts


it is the circulating fan or its motor!

there isn't a way for me to access it. our's is a little different. the motor is inside the circulating fan, the only access is from the front (shown in this diagram) and the air filter is actually on the bottom.
Yes, it runs before the furnace and induced draft fan.

i just looked again and i can't access the motor or squirrel cage without dismounting them. i'll call and get quotes to replace both. THX!

on a totally different subject. Energy savings. the furnace/thermostat is set to keep the temp right at 68F. when it drops to say 67F, it turns on. when it gets to 68F, it turns off. it would be much nicer for the furnace (and AC) to turn on at say 65F and turn off at 72F. this way, it'd run a few times an hour. right now it is on-off-on-off-on.... well, maybe it wouldn't save energy, but it would be much easier on the HVAC units. i think. any ideas?

Nap, thank you very much for all your help!

rosco
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Old 01-04-2010, 09:09 AM   #10
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What runs before furnace starts


I'm certainly no furnace expert, but have worked on many an electric motor and motor/fan combos. I know enough about HVAC work to know that it does sound odd that the circulating fan comes on before the unit lights up. Having the draft inducer come on first sounds logical, but not the circulating fan. "rosco" states that the noise if coming from the circulating fan unit itself. "nap's" description of the oiling hole is common to what i am used to, and some of them are not easily accessible while in the HVAC unit. I've had to remove the circulating fan and even remove the motor from the housing to find the oil holes. A lot, maybe most, of these type motors have a bushing in them that is surrounded by a felt membrane which holds the oil. The bushing is made for sintered bronze which will allow it to wick the oil from the felt through the sintered bronze for lubrication. It's important to get the felt membrane full of oil, but not to overdose it, there's the challenge. At this point, IF you are comfortable with working on this unit, I would turn off the power to the unit, look to see if the circulating fan unit is easily removed, and IF so remove the unit for a cleaning and lubing. Good Luck, David
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Old 01-04-2010, 10:29 AM   #11
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What runs before furnace starts


Nap & Thurman -
since replying to Nap, i've wondered if maybe it wouldn't be too hard to remove power to unit and remove for cleaning and lube.

The visible part of the motor is covered in dust. i can't see enough of the motor to make out if the motor is easily dismounted from the squirrel cage.

either way, i'm much further ahead now. I know what is squeeking and have gotten quotes.

-r
ps. i'm now noticing the circulating fan to come on after the furnace and inducer fan. maybe the circulating fan just hadn't shut off from the previous cycle. the circulating fan runs after the furnace shuts off. ....but who knows. lol
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Old 01-04-2010, 03:09 PM   #12
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What runs before furnace starts


you remove the entire squirrel cage with the motor in it as a unit. Most fans such as this have 2-6 screws that hold it in and once they are removed, the fan unit simply slides out.
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Old 03-20-2010, 10:57 AM   #13
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What runs before furnace starts


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Originally Posted by rosco View Post

on a totally different subject. Energy savings. the furnace/thermostat is set to keep the temp right at 68F. when it drops to say 67F, it turns on. when it gets to 68F, it turns off. it would be much nicer for the furnace (and AC) to turn on at say 65F and turn off at 72F. this way, it'd run a few times an hour. right now it is on-off-on-off-on.... well, maybe it wouldn't save energy, but it would be much easier on the HVAC units. i think. any ideas?

Nap, thank you very much for all your help!

rosco
I'm not at home right now and some of the experts could tell you more but I bought a programmable thermostat for my forced air furnace and I think it has a function that allows you to set the parameters of operation like you are asking about. I can adjust the temperature range of when it decides to turn on based on my desired temperature. I don't know if it can do the range you are suggesting though.

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