Noisy Blower Remedies vs (Yet Another) New Furnace

[onnad]

I posted a while ago. Just had a new furnace installed last month. My HVAC contractor recently recommended and installed at 125,000 BTU Tempstar, single stage burner, PSC blower furnace in my 22 year old home to replace a 22 year old 140,00 BTU Bryant furnace. Basement installation in a very large utility room.

The Tempstar circulation blower is LOUD - way, way more circulation blower / motor noise now gets transmitted through the ductwork compared to the 22 year old Bryant furnace that was replaced. The noise is a low rumbling, "train like" sound whenever the blower is on - it's not an air velocity noise.

I complained to my contractor about the noise and he turned blower from setting 3 down to setting 2 - it reduced air velocity noise BUT didn't help at all with rumbling, "train like' noise from circulation blower / motor.

A couple of questions:

1) The Tempstar PS 80 does not have an insulated blower cabinet. If my HVAC contractor put sound absorbing insulation on all six sides of the blower compartment, would that help reduce the rumbling blower noise?

2) Would a section of flexible duct material installed between furnace and plenum reduce the blower noise being transmitted through the ductwork?

3) Are there "aftermarket" PSC blowers that my HVAC contractor could install that would be quieter than the factory standard Tempstar PS 80 PSC blower?

4) My research indicates the Tempstar PS 80 is a basic, builder grade furnace. My highest priority is a quiet, quiet, quiet furnace. I noticed Lennox advertises some of their furnaces are 4 or 8x quieter than competition. Any recommendations on which brands are truly ultra quiet models in a basement installation?

Don't want to take out a brand new (but noisy) furnace.....but I'm willing to consider if that what it takes to get something that is as quiet as the "obsolete" 22 year old Bryant furnace that was just removed from my house........

Thanks for your help

[motoguy128]

It unfortunately sound like you got what you paid for. Did you tell you installer that a quiet system was improtant up front? You might be able to beg the installer to switch out the unit (with some restocking fee) along with the increase price to a 2 stage vairable speed unit. You'll be much happier.

Also make sure they install soem sounds reducing material in the return plenum. Also, you generally don't want any ducts attached directly to the supply plenum. Thye should be located on main trunk lines at least a few feet downstream.

Is the noise whistling or or turbulence form high velocity at the ducts? Or is the noise sounds form the blower motor transmitted through the ducts? If the sound is form high velocity, and it only occurs on some ducts, you might need to do some balancing. It's usually pretty cheap to have manual dampers installed on each supply branch.

My system had some noise and balance issues. I resolved it by rerouting 2 of the branches further downstream and installing dampers to balance all of the other branches.

[thump_rrr]

First of all a canvas connector is a must to isolate the furnace from the ductwork.

Is the rumbling heard through the ductwork or felt through the structure of the home?

[beenthere]

1150 is too low of an air flow for that size furnace.
That puts you just over an 80°F temp rise.
If the furnace is listed that 80 is the max rise. Then as soon as the air filter gets a little dirty, it will start to over heat the heat exchanger.

The furnace is most likely too big for your duct system.
The old furnaces operated at a much higher temp rise, and didn't need as much air flow.

Do your own load calc, and find out what size furnace, you really need.

It is always possible, that the motor has a bad bearing from new.
But, even if that is the case. With that low air flow over the HX, your looking at a short life span for it.
And Tempstar will only warranty the HX once. After that, you'll be paying for it.

Switching to a new furnace of the same BTU with a VS blower, will only help, as long as it doesn't have to go to second stage. Once it goes to second stage, you will have loud noise again.

[onnad]

Thanks for quick feedback everyone.

Motoguy128 - the 22 year old furnace died at 11:00 pm on a Sunday evening in Chicago when it was minus 10 outside. My HVAC came out and said he could put in a furnace the next morning at 7:00 am - I had 8 hours to make up my mind on furnace. I didn't know noise was an issue on new furnaces until the new one was put in because the 22 year old furnace was whisper quiet - after researching the last 30 days I now understand the difference between ECM vs PCS blowers, single stage vs multi stage burners, sound insulated cabinets vs not, etc. I asked HVAC guy why he didn't recommend to me a 2 stage burner / ECM - he said they were expensive and tended to break down more. He offered to take out the new Tempstar and put in variable speed / 2 stage if necessary.........

Thump-rrr - the noise is rumbling through the duct work. It doesn't sound loud next to furnace but seems to get "amplified" through duct work. Same issue with new AprilAir humidifier - when solenoid valve engages - the "tiny" noise in the basement gets "amplified" to huge "thump" throughout ducts.

Beenthere - thanks for insights. Contractor also installed Aprilair electrostatic filter - don't know what impact that would have on heat rise (if any)

Ironically, the only thing wrong with 22 year Bryant was that Blower failed...should have just replaced the blower vs putting in new furnace. Bryant wasn't efficient but was QUIET.

Any thoughts on which specific models actually are quiet under operation??????

[beenthere]

That filter is reducing your air flow also.
Thry a cheap standard air filter.
It may make teh noise louder, or quieter.

[DanW13]

Gee if the blower motor was the only thing wrong and you were in a pinch IMO I would have just had the motor replaced until such a time you could investigate brands, bells & Whistles of all the equipment available today and not have to make a snap decision. A blower motor for a older furnace you did have would robably only cost a very small percentage of what the new furnace cost and would have given you probably until next heating season to get it replaced. There are ECM motors available for replcement of PCS motors but then again oing that route it would be putting good money into a old piece of equipment. If your installer is willing to change what you already have there to a 2 stage VS blower motor then I would definately have him do it and pay the upgrade charge, just be sure the furnace is a ECM VS blower motor, the savings will be huge on the electrical side of things epsecially if your one that runs your blower 24/7 to keep the air filtered and moving thur out the home to balance your ID temps and the cost for the upgraded furnace over what is currently there will be returned pretty quick. I have saved nearly 60% on the electrical side with my new Infinity 58MVC and to run the blower 24/7 cost maybe $5-$6/month.

[onnad]

Beenthere - thanks for the follow up. Unfortunately, the AprilAir electrostatic filter and AprilAire humidifier were installed brand new with the Tempstar furnace last month. I'd prefer not to take the AprilAir filter out since I paid extra to have it installed a month ago with the new Tempstar.

As a first step, I'm trying to find a way to reduce the PSC blower rumble being transmitted through the ducts - if possible - before taking out the AprilAir filter or replacing the now 1 month old Tempstar furnace with another brand / model that is hopefully as quiet as the 22 year old "antiquated" Bryant that was replaced a month ago.

That was why I was inquiring if anyone had success with putting sound absorbing insulation in blower cabinet or installing a flexible duct connector between furnace and plenum to try to reduce the blower rumble......

From prior post, someone also suggested increasing return duct size to try to reduce blower "roar". In my application, it would not be easy to replace duct work as supply and return main ducts are on the other side of a finished drywall ceiling in my basement - would be a significant job rip out dry wall ceiling, etc to get at existing ducts to replace.

DanW13 - good point but the extra service charge my contractor wanted to put in a new blower in a 22 year old furnace at midnight on a Sunday evening was significantly more than you would have guessed and led me to agree with him that it might make sense to put in a new furnace the following morning. I agreed with his Tempsar recommendation since he had 20 years of HVAC experience and I have zero.

Live and learn.

[tedkidd]

Any thoughts on which specific models actually are quiet under operation??????

Sounds like you had good luck with Bryant - Bryant Evolution "quietest furnace you can buy" would have been a good choice. Also sounds like you have a huge house! Can't imagine what takes a 125,000 btu furnace!

Sorry for your unfortunate spot, hope you don't mind my using it to help others understand why they might not want to wait 22 years before looking into replacement options? You put it so nicely:

...the 22 year old furnace died at 11:00 pm on a Sunday evening in Chicago when it was minus 10 outside. My HVAC came out and said he could put in a furnace the next morning at 7:00 am - I had 8 hours to make up my mind on furnace.

I didn't know noise was an issue on new furnaces until the new one was put in because the 22 year old furnace was whisper quiet - after researching the last 30 days I now understand the difference between ECM vs PCS blowers, single stage vs multi stage burners, sound insulated cabinets vs not, etc.

I asked HVAC guy why he didn't recommend to me a 2 stage burner / ECM - he said they were expensive...

I'd never recommend a $xxxx (hypothetical cheap number) furnace, in fact I'll strongly recommend against it. But if that's what you request - if I don't facilitate I'll lose my job.

Did you ask for advice or simply tell him you wanted a cheap replacement. Did you treat him like a trusted expert, or like an oil change mechanic.

I suspect the HVAC guy didn't recommend nicer equipment because you indicated you wanted something cheap. After the fact, you asked why he didn't recommend MS/VS equipment, this is pretty unfair. You show up looking at Chevy Aveo's, indicate your budget, then are disappointed I didn't encourage you to look at Sedan DeVille's?


Hypothetical numbers, tend to bring questions like, how close was your install to that hypothetical number.

[motoguy128]

Thanks for quick feedback everyone.

Motoguy128 - the 22 year old furnace died at 11:00 pm on a Sunday evening in Chicago when it was minus 10 outside. My HVAC came out and said he could put in a furnace the next morning at 7:00 am - I had 8 hours to make up my mind on furnace. I didn't know noise was an issue on new furnaces until the new one was put in because the 22 year old furnace was whisper quiet - after researching the last 30 days I now understand the difference between ECM vs PCS blowers, single stage vs multi stage burners, sound insulated cabinets vs not, etc. I asked HVAC guy why he didn't recommend to me a 2 stage burner / ECM - he said they were expensive and tended to break down more. He offered to take out the new Tempstar and put in variable speed / 2 stage if necessary.........

Thump-rrr - the noise is rumbling through the duct work. It doesn't sound loud next to furnace but seems to get "amplified" through duct work. Same issue with new AprilAir humidifier - when solenoid valve engages - the "tiny" noise in the basement gets "amplified" to huge "thump" throughout ducts.

Beenthere - thanks for insights. Contractor also installed Aprilair electrostatic filter - don't know what impact that would have on heat rise (if any)

Ironically, the only thing wrong with 22 year Bryant was that Blower failed...should have just replaced the blower vs putting in new furnace. Bryant wasn't efficient but was QUIET.

Any thoughts on which specific models actually are quiet under operation??????

Sounds like the installer is being pretty helpful. His first priority was to get you heat, which he did. Now is your chance to get it done right.

Whatever unit you select, make sure it's sized correctly by having a load calculation done. I think my Trane VS furnace is pretty quiet. I suspect most if not all the VS furnaces have extra sound reducing material in the cabinet.

Next make sure the ductwork is sized properly, mainly the supply and return plenum and first sections of main supply and return trunks. It's like a highway. If you have a 3 lane highway merge with a 2 lane highway, you need 5 lanes if both are at maximum capacity... otherwise the cars will need ot increase their speed to get more traffic volume.

[superheatrman]

A cheap solution to noisy blowers. they work well, dime store vfd...
http://www.fanhandler.com/

[cmajerus]

very possible it is a blower wheel that is off balance, or furnace is oversized for the ductwork. Have him check the static pressures. And I always install flex connectors, they do help reduce vibration transfer. Insulating the cabinet may help, but doubt that is the major issue.

[BURL-REF]

I have to agree on the rumble being a bad blower wheel. Call them back to look at the blower wheel, and reset the rise on the furnace.

[motoguy128]

A cheap solution to noisy blowers. they work well, dime store vfd...
http://www.fanhandler.com/

Looks like it's basically a low price single phase VFD, but it does appear they have some simple loop control using temperature sensor or switches and a slow amp rate for the VFD. Not bad really. Good for comfort, althouhg you'll give up some effecincy on a heat pump, since more airflow provides better heat transfer.

[onnad]

Thanks for all your posts. I spoke with my HVAC contractor today. Here's his views on the Tempstar PS 80 single stage, PCS furnace he installed a month ago.

1) On issue of furnace beings oversized for application. He's absolutely adamant - I mean adamant - that my 3 level 4,400 sq ft colonial home (3,400 sq ft on main level and top level, 1,000 sq ft in finished and heated basement) is properly sized at 125,000 BTUs. I'll buy the Manual J software to confirm or refute this but he doesn't think improper furnace size is the issue. Instead...........

2) He thinks the home should have been designed for two furnaces (each around 60,000 BTUs) one in basement and one in top floor. He said the 125,000 BTU furnace has big burner orifices and large blower which is creating the rumbling noise.

3) He didn't recommend a two stage, variable speed blower furnace because he thinks a VS might be actually as loud as the Tempstar PS 80 because he has set the blower at 1,100 CFM (level 2) on the Tempstar.

Here's his solutions to the rumbling noise:

1) Install sound absorbing insulation in plenum

2) Install sound absorbing insulation in Tempstar PS 80 blower compartment (although he doesn't think that will reduce noise much)

3) Install flexible duct connector between metal plenum and metal furnace housing to reduce vibration noise transmission

4) If all that fails to fix the noise issue - he did offer to put in a two stage, sealed burner, variable speed blower furnace - but it will be a Tempstar VS 80 - because that's the line he carries

Thoughts on whether his plan is logical? Thanks for your perspectives.

[beenthere]

Can you measure the size of the duct/ducts, that come off the supply and return plenum.

At 1100 CFM that furnace is probably not going to last too long.

Flex connector will eliminate vibration. But doubtfull its going to help with rumbling noise.

[motoguy128]

He said the 125,000 BTU furnace has big burner orifices and large blower which is creating the rumbling noise.
.

Really? Maybe on a Tempstar, but on Carrier and Trane furnaces they simply use more burners, all the same size. It makes it much cheaper to produce. The larger ID fan and larger blower could cause rumbling, but it's more likely the chaep uninsulated housing is causing most of it.

Sounds a little like he's just making excuses to avoid changing out the unit.

One negative about adding sound absorbing matieral, it will reduce the inner dimensions of the ductwork, which can increase air velocity.

He is right that a VS blower isn't nesseasarily quieter, but the sounds proofing common on those units helps quite a bit. But undersized ductwork doesn't help.

I don't disagree that that is a large home for a single furnace. Again, wiht proper ductowkr it can work, but the distances may be a little long to the far bedrooms and it could be hard to balance. Imbalance issues can also cause noise where a few ducts have high velocity.

[onnad]

Beenthere - I measured the ducts. Here are the sizes

1) Plenum attached to furnace: 55x23x23.

2) Largest supply duct: 8x24 and probably 20 feet long (runs length of basement)

3) Second largest supply duct (juts off from large supply duct within first 12 inches): 9x 12 inches and probably 20 feet long (runs parallel to first supply duct)

4) Third largest supply duct (juts off top off main supply duct within first 12 inches) 9 x 9 square and probably 12 feet long

5) Fourth and fifth largest supply ducts (juts off front of main supply duct) are 9 inch circles and probably about 6 feet long.

There are multiple smaller ducts that attach to each of these 5 main supply ducts throughout the house

Return duct: 10 inch x 24 inch square by at least 20 feet (runs the length of house parallel to supply ducts). There are multiple cold air return circular return ducts that feed into the master return duct and a couple very large rectangle returns that feed into the master cold air return as well.

Beenthere - when you estimate furnace won't last long at 1100 CFM by not long do you mean 4 - 5 months or 4 - 5 years? The noise from the Tempstar at Blower Setting Three (around 1500 CFM is intolerable) - way too much duct work roar.

Thanks

[beenthere]

Probably several years.

With the 8 x 24 being the main supply trunk(all other ducts tap off it).

A VS will probably make noise when it goes to high fire.

The old furnaces had a very high allowable temp rise. So they didn't move much air.

[onnad]

Been There - sorry; I missed a couple main supply ducts. At the other end of the house there are two 12 - 15 inch circular ducts that run perpendicular to main supply duct.

Off of all the supply ducts there are 7 inch circumference circular ducts branches that actually go to each room in the house. There are 14 of these ducts on the first floor, there are 10 of these ducts on the second floor of the house and there are 6 ducts in the basement (30 supply ducts in all the rooms on the three floors). The actual size of the duct vent in the floor of each room are 10x3 in a rectangular shape. Some of the grills are wooden and some metal. The wooden ones are quieter than the metal ones.

There are 16 cold air return ducts (6 on first floor, 8 on second floor, 2 in basement) that are 10x5 in a rectangular shape vent shape. The cold air returns on the first floor are located about 6 inches off the floor. The cold air returns on the second floor are two per room - one 6 inches off the floor and one 12 inches from the ceiling. All the cold air return grills are metal.

The furnace is in a large utility room in the basement - probably sized 10 feet by 10 feet and gets plenty of air as it's open to a crawl space which is about 10 feet by 20 feet at one end of the house.

Ironically, when you stand next to the furnace in the basement; it's not loud - but sound seems to be amplified through duct work on the second and third level of the house, particularly in those rooms with feeder ducts very close to furnace and plenum. Blower noise is not an issue for rooms very far away from furnace on second and third floors.