Furnace blower overly noisy?

[gshort71]

Have been in a new build house for almost 3 years. Purchased a high efficiency Carrier furnace to be installed with the build.

From the very start, the furnace was loud. The company that did the installation cleaned the blower wheel of drywall dust and it helped with some of the noise. Once summer came and the blower ramped up for A/C, it got really noisy. The main floor return was where the bulk of the noise came through. Called the installer again, but all they did was turn the fan speed down so it wasn't as loud. I delt with it until it started getting louder.

This spring I decided to finally get something done about the blower noise. I discovered on my own something the installer missed every time they came out, the return duct going into the furnace was undersized. I hired a company to take a look and they did the quick calculations for my system and sure enough, it was undersized by 2". They replaced the return that the upstairs and main floor returns fed into, but the noise actually got a little worse.

Since the furnace was still under warranty, I hired the local Carrier dealer and warranty people to take a look at it. They believed it was either the blower motor or the main floor return was undersized. Carrier told the dealer it was probably mechanical and they replaced the blower motor. Noticed a huge reduction in the noise I was hearing from the main floor return, but I started noticing a vibrational hum. Almost like a clothes dryer was running in an adjoining room.

The noise appears to be in the same location of the furnace that the previous noise was coming from. It seems to be a vibrational hum that you can hear on the main floor and through the return air duct on the main floor. Since we have never had a quiet blower motor, is this normal? Is it the blower motor or something else vibrating? The Carrier installer & warranty company suggested a new Infinity furnace for quiet operation. Yikes, alot of money! There has to be a better solution. Help!!!!!!

[beenthere]

Edit out the price, its not allowed here.

Have them check the blower wheel, see if its out of balance.

[t527ed]

Edit out the price, its not allowed here.

Have them check the blower wheel, see if its out of balance.



ditto

[gshort71]

Carrier warranty company replaced blower wheel early on, thinking that could be the source of the noise. Although the old one appeared to be slightly warped, it didn't seem to make a difference in noise with a brand new one. About a month later is when they also replaced the blower motor. So at this point the blower motor and wheel have both been replaced.

[Focko]

Might be something got sucked into the blower wheel, putting it out of balance. If you open it up and look at it you might see a piece of insulation or something stuck in it. That's an easy fix if that's what happened.

Edit: Do not do this unless you are CERTAIN the power is turned off to it.

[beenthere]

Have them set up an appointment for the CARRIER rep to come out with them.
Not just talk about the noise over the phone.

[Freezeking2000]

I personally do not think it is Carriers fault. Sounds like a install issue, you should not have a loud heating system with any brand if installed properly.

[zaneman]

I believe you have an installation problem with harmonic sounds in the duct system. Why don't you consult your installation manual and have your installer go over the job with you? Carrier is known for quiet operation should the unit be installed properly. You stated the duct sizing was inadequate how is the workmanship on the total install? Just a few suggestions for you to check out. The last thing you need is a new furnace!

[gshort71]

The Carrier warranty company also pulled the furnace to clean it and check for problems. Other than being extremely dirty from the build, it appeared fine. Could they have reinstalled it improperly or was it already that way and they just returned it to its original state when reconnecting it?

[woody19]

Have someone check your duct installation to insure it is sized/installed correctly and see what the static pressure is. This should be done and not just guessed at.

[gshort71]

I have talked to the service rep and Carrier rep, together. They think it could be to much air flow and will be coming out to check things out.

[tedkidd]

I have talked to the service rep and Carrier rep, together. They think it could be to much air flow and will be coming out to check things out.

Never heard of too much airflow. Can someone explain this to me?

[powerup]

Do you have metal ducting and if so, are there isolation dampers before and after the airhandler.

[captube]

Sounds like the furnace was used for construction heat.

Vibration from running dirty will cause fatigue in the mounting brackets and blower ass. mounts. Don't run furnaces for construction heat. :)

[Focko]

What??? :eek::D

[gshort71]

I do have metal ducting. I have isolation damper before furnace, but not after. I still get the noise up through the return side anyway.

In response to captube, the furnace was run dirty under construction. Does that mean the mounting brackets and blower ass. mounts need to be replaced? Is it even possible to replace them?

[gasguy]

If the return ducting is attached tight to the floor joists, it will transmit and sometimes amplify any small noise/vibration. There should be flex connectors between the unit and the main trunk to stop transmission of noise/vibrations.

[gshort71]

Sounds like the furnace was used for construction heat.

Vibration from running dirty will cause fatigue in the mounting brackets and blower ass. mounts. Don't run furnaces for construction heat. :)

Service company is soming out this week to inspect furnace. Can brackets and mounts in the furnace be repaired or does the whole furnace have to be replaced?

[captube]

They are coming back, that is a good sign.

They could find some other reason for the vibration, but it sounds like they are going to solve it.



Service company is soming out this week to inspect furnace. Can brackets and mounts in the furnace be repaired or does the whole furnace have to be replaced?

[aaCharley]

I'm havaeing a similar moise and vibration problem with an installation of a replacement furnace system. The unit is a rheem 90 Plus Modulating gas. The unit is located in the basement and connected to the 50 year old metal duct system.

I complained about the great increase in noise compared to the old system. The installer replaced a few feet of supply duct near some registers with some flex and it quieted those down. Most of the remaining noise is comming from the return. It is still pretty loud. I can also feel the vibration in the floor when the system runs.

Other posts in this thread reference using "isolation dampers" and "flex connectors" to reduce the noise problem. I had earlier mentioned this to the installer. He did not believe that these were necessary. It seems that they would only help with the problem and I'm willing to pay for the installation. Can someone post a link to show me what these would look like and how they are incorporated in the duct work. I'd sure appreciate seeing these so that I can talk about it a little better. I guess I should have been more insistant on what I wanted installed. But the installer is the pro so I went with his judgement. Now I seem to need some remedial work and could use a bit of direction.

[beenthere]

Flex connectors will help with vibration. But not with grille noise of the return.
That could be undersized return duct, grille, or a combination of both.

[Airmechanical]

Have been in a new build house for almost 3 years. From the very start, the furnace was loud. I hired the local Carrier dealer and warranty people to take a look at it. They believed it was either the blower motor or the main floor return was undersized. Carrier told the dealer it was probably mechanical and they replaced the blower motor. Noticed a huge reduction in the noise I was hearing from the main floor return, but I started noticing a vibrational hum. Almost like a clothes dryer was running in an adjoining room.


without being at the jobsite my initial opinion is;

i beleive your first problem is the entire duct system is undersized!

the repair that they did for you was a bandaid (and not a very good one)

i am gonna leave it at that!



.

[Freezeking2000]

Flex connectors will help with vibration. But not with grille noise of the return.
That could be undersized return duct, grille, or a combination of both.

On a modulating furnace i would not think it would be a grill noise since it would be in low fire most times.

[beenthere]

On a modulating furnace i would not think it would be a grill noise since it would be in low fire most times.
Good point.


I over looked the mod factor.

[WhoIsThat?]

There is "white noise", which sounds like a waterfall and contains all frequencies.

There are resonances, which should be damped out by properly selected isolation mounts. All mounts are not the same.
http://www.google.com/search?hl=en&q=%22frequency+response%22+isolation+shock+mount&btnG=Search

[Airmechanical]

There is "white noise",



your watching too many movies!:p



.

[WhoIsThat?]

your watching too many movies!:p.
That, too.:o
http://en.wikipedia.org/wiki/White_noise

[gshort71]

Wow. Lots of info here. I had a 15 point inspection done on the furnace. It is getting the right amount of airflow. The blower motor was replaced earlier this year, so the connectors where all new and not loose and stressed from running dirty, like the previous motor could have been.

It looks like I'm having the same problem as aaCharley, in that a minimal amount of vibration in the furnace is being conducted and magnified through the floor and wall. While in the basement during the inspection, I noticed that the furnace return for the main floor runs along a load bearing wall braced by a steel beam. The hum/vibration on the opposite side of my living room also has the same supporting steel beam. I'm guessing that I need to look into isolaters and anti-vibrational material as well. Is this something I can do myself? Anyone have any suggestions?

[dash]

www.durodyne.com They are in the Glassline Catalog on this site.

Quieturn Vanes for 90 degree elbows.They stop the motor noise from making the turn,eliminate noise from turbulence.

[mchild]

www.durodyne.com They are in the Glassline Catalog on this site.

Quieturn Vanes for 90 degree elbows.They stop the motor noise from making the turn,eliminate noise from turbulence.

dash,

Just wanted to confirm that the quieting vanes you are referencing will also work in metal duct just as they do in the fiber duct shown in the manufactures catalog?

[glfdad26]

Better get the static pressures checked

[aaCharley]

Do you have metal ducting and if so, are there isolation dampers before and after the airhandler.


I am having a similar noise problem. System is a Rheem HP combined with the Mod90 furnace. The installer was here and took the line set down from being tightly attached to the floor joists in the basement. That did help with noise in heat pump mode. However, there is still a good bit of noise and floor vibration from the blower in the furnace when in either HP or Gas mode. noise is primarily from the first return duct. I would very much like to find the Isolation Dampers. I want to get the installer to put them in. He does not seem to want to get them, evidently they are made up for each job and he does not have the flex material. Is there a source for locating these so I can ask him to give them a try on killing the noise. I was expecting something a lot quieter than the old furnace I replaced.

[snupytcb]

if it is a low humm it could be the inducer making noise. is the furnace on any anti-vibration pads? does the return have a rubber transition collar to dampen the noise?

[aaCharley]

I'm a bit perturbed by the installation. No, there are no vibration pads. In fact, the furnace is set upon a metal sheet metal box. The furnace is an upflow model. Return air is connected to one side of the box, furnace is set on the other side and the box connects for the air supply. I did not like it when it was going in. The pro doing the install told me that it was standard practice and that airflow would be better in that configuration. I'm sure that the box is acting as a noise echo builder and flow restrictor as it needs more turns than just hooking up the return air through the side of the furnace. In any event, there are no vibration dampening pads or feet used. The way it is set up, that light weight box is actually more likely to be operating as a trampoline.

[tedkidd]

I'm a bit perturbed by the installation. No, there are no vibration pads. In fact, the furnace is set upon a metal sheet metal box. The furnace is an upflow model. Return air is connected to one side of the box, furnace is set on the other side and the box connects for the air supply. I did not like it when it was going in. The pro doing the install told me that it was standard practice and that airflow would be better in that configuration. I'm sure that the box is acting as a noise echo builder and flow restrictor as it needs more turns than just hooking up the return air through the side of the furnace. In any event, there are no vibration dampening pads or feet used. The way it is set up, that light weight box is actually more likely to be operating as a trampoline.

Not much of that makes sense. Maybe a picture would help.

Not sure how "more turns" could occur. Are you suggesting the hvac guy spent a bunch of his money to purposely build a contraption out of metal to restrict your airflow when he could have built something less expensively and better? Why would he do that?

If your box allows bottom and side return, then it indeed allows a tremendous improvement in airflow.

[aaCharley]

Look at the pictures of the install that this person got:
http://hvac-talk.com/vbb/showpost.php?p=1977624&postcount=1

The shiney metal box at the bottom is very much what I have. The installer did not fabricate it, it is a standard piece available from a supply house for this purpose. Airflow runs down in the return duct, into and through the box, then up into the bottom of the furnace. The installer purchases the box and cuts the two holes in the large flat upper side to accomodate the sizes of the return duct and furnace. The overall size of mine is about 10.5" X 27" with no liner. Any furnace vibrations could be amplified and transmitted to the return duct through the box. It has no isolation material or absorption material under it. Since the furnace is hard connected to the supply ducts they get the vibrations also. The return duct is also hard connected to the box so that whatever is vibrating at the furnace will transmit to the return system. By "hard connected" I am trying to convey that there is no flex connector or isolation material to absorb any vibration.

I would like to find a source for some isolation connector to use at the top of the furnace where it joins the plenum and at the top of the return duct before it gets to the horizontal section attached to the floor joists. Since several people have mentioned it in this thread, I hoped someone would provide a source for the items.

[gshort71]

I took a break from solving my issue about a vibrational hum in certain areas of the house from the furnace. As stated earlier in my thread, I have replaced the blower, the static pressure is fine, the duct work appears to be properly sized, and I have a flex piece between the furnace and return. I am planning on hiring a company to try and finally resolve it, but need some further advice and direction.

I think it could be harmonics that others have described, but I don't understand the locations of the hum and intensity. You can notice it standing over the furnace in the kitchen, but it's much louder in the entrance way to the house which is actually far from the furnace and around a corner. I can hear it coming from some supply ducts, but not others. The ones farthest from the furnace seem to be louder, but even they aren't as noticable as just standing in the hallway away from any duct and hearing it all around you, without a easily found source. It literally sounds like someone is running a piece of equipment somewhere in the house.

The basement, where the furnace is located, is actually much quieter than the upstairs. I only hear the sound of air until I get right next to the furnace and then I can sort of hear what I notice upstairs, but not very loud at all.

I can touch the floor beams that the return is mounted to and feel vibration, even though there is flex between the furnace and return. Does it all come down to needing isolators? If so, are there specialists for this type of work? Why would the hum be worse further from the furnace than closer?

I want to finally put this problem to rest. Please help.

[tedkidd]

Maybe, like blowing through a flute, you have the perfectly sized hole for the frequency you hear. You could have your duct work sealed. Here's the approach I would use:
Have your duct leakage tested.

Then have duct's sealed.

Then test again to determine leakage reduction and know what result you got for your $.


There are two potential benefits and little downside to this work. Even if it doesn't kill the noise the increased energy efficiency should justify the work.

[Ladiesman271]

You may need to isolate the duct work from the furnace. My setup has a sound isolator between the furnace and both the return and feed ductwork.


http://www.ecoduct.com/forms/Flexible%20Duct/Duro%20Dyne%20Flexible%20Duct%20Connector.pdf


You say that you have an isolator on the "return" duct. Do you have an isolator on both the feed and return ducts?

[hvac-learning]

If the noise is located at the r/a registers in the rooms maybe noisetransmission through the duct work and flexable connectors were not installed. or what sized Carrier heater some blower sizes require both sides of heater to get r/a duct or bottom and 1 side to get r/a duct. 4ton blower and 5 ton require this. in the modle# ending 2 numbers -16 or -20

[aaCharley]

Thanks for posting the link to the flexible connector and where it is available.