High efficiency furnaces noisy fans

[M.alex]

Had 3 30yr old Carrier furnaces. The heat exchanger cracked on two of them and I got suckered in to replacing them with new Lennox high efficiency furnaces rather than try to repair.

Now when the furnaces turn on there's an irritating low pitched whine coming from all of their fans that you can hear all over the house. The installation company has been back several times and tried doing a few things like lowering the fan speeds, but on the 3rd call gave up and said it's normal because today's units use much bigger fans so you're going to hear them running and to just live with it.

Such bullshit that a 30yr old furnace is basically quiet when running and new ones are noisy pieces of shit - are there any brands that are whisper quiet when running, or upgraded fans or something to make it quiet? I'd happily pay to rip these POS out and put new units in if I could find a quiet one (but I don't think you can go to the store and ask for furnance demos of various brands???)

[ThePenIsMightier]

I think I've heard people say that the fans running on DC motors are quieter.

[ExtraSlow]

Is it just for a second at startup? Or constantly?

[M.alex]

Is it just for a second at startup? Or constantly?

whenever the furnace is running. Like a constant 'weeeeeeeeeeeeeeeeeeeeeeeeeeeeee' that gets louder (higher pitched) as the unit ramps up (Lennox 296 variable speed), and immediately stops when the furance stops running.

all 3 make the same noise when they're running.

when I look up reviews of the unit everybody either gives it 5 stars and says they love it, or 1 star and says they hear a low pitched noise that drives them crazy when it's running.

i'm happy to pay $20k to rip out brand new furnaces and replace them for my sanity, but i have no idea how to view furnace demonstrations to see if all furnaces do this today or not.

my basement is undeveloped so they just sit in the middle of it .... perhaps all high efficiecny furances do this and they expect them to be put in an isolate room in the basement that is sound deadened???

[suntan]

It's just part of the new normal.

[M.alex]

It's just part of the new normal.

I hope not, this is god aweful irritating.

[msommers]

We have a Carrier Infinity 96 and I never get that. Couldn't tell you if that's a shit furnace or a great one but seems to do the job.

The ducting on our second story dings and pops though which is fucking annoying. Basement and main floor are fine, 2 floor it's like a gnome is in the wall flicking the ducting every so often. I assume expansions/contractions and I don't know how you fix that.

[ThePenIsMightier]

I bet a major nerd could figure out how to isolate and dampen portions of the ducts to mitigate this noise for way less than the cost of new furnaces. Don't call Wood (Beta Machinery) for help with this if you're looking for said nerd.

This sounds like your place is going to turn into The Shining.

[suntan]

We have a Carrier Infinity 96 and I never get that. Couldn't tell you if that's a shit furnace or a great one but seems to do the job.

The ducting on our second story dings and pops though which is fucking annoying. Basement and main floor are fine, 2 floor it's like a gnome is in the wall flicking the ducting every so often. I assume expansions/contractions and I don't know how you fix that.

Look into Aeroseal.

[Swank]

It's just part of the new normal.

My furnace wears a mask, super quiet.

[CarlLester]

We got two new Carrier Performance furnaces and they dont have any whine.

When we were shopping around JPS were selling furnaces which they said were the quietest you can get (they have them set up in their showroom so you can hear for yourself). We didn't go with them though as the reps who came to our house couldn't actually answer any questions. They also dont do any of the ductwork, just install the furnace, and we needed everything done.

[Ca_Silvia13]

We have a Carrier Infinity 96 and I never get that. Couldn't tell you if that's a shit furnace or a great one but seems to do the job.

The ducting on our second story dings and pops though which is fucking annoying. Basement and main floor are fine, 2 floor it's like a gnome is in the wall flicking the ducting every so often. I assume expansions/contractions and I don't know how you fix that.

That's called "oil canning" and you can fix it but being that it's your 2nd floor ducting it's probably not worth the hassle to rip up flooring and or the main floor ceiling.

[v8killa]

This was happening on our new build and they discovered that the furnace wasn't 100% sealed causing a low pitched whistle...they fixed it and now its all good.

[?????]

Can you hear the noise when you're at the source (fans) or just hear it from the vents and returns?

[M.alex]

Can you hear the noise when you're at the source (fans) or just hear it from the vents and returns?

Returns are quiet; vents are making the noise. I think the furnace is also making the noise but I can't tell for certain when I'm right on top of it

However, what i found is that if I remove the filter and leave the front furnace door open (which exposes the wires, etc.) the noise is like 99% reduced. If you strain you can still make some resonance out, but just barely.

Maybe it's not a furnace issue but some type of ducting/air-flow issue? Not enough/too much air based on existing duct sizing?

[suntan]

Maybe put in a cheaper filter?

[msommers]

+1. Our home inspector mentioned that all the really thick (expensive) furnace filters end up choking your furnace making it work harder. Their advice was to get a cheapie filter and if you really need the filtration get a proper air filter.

[whoreads]

Not enough/too much air based on existing duct sizing?

Just dealt with this issue after I had a new 96% efficiency Goodman put in last month; the old furnace had an annoying harmonic resonance that could be heard in some parts of the house but now it's gone.

However, the ducts are much noisier due to the greatly increased air flow and then, after a few weeks, it stopped working.

The guy suspected everything from critters in the vent to pressure switch and high limit switch but ended up replacing the inducer motor and advised me to use the cheapest filters.

[ExtraSlow]

You guys need the furnace filters mega thread.
https://forums.beyond.ca/threads/411253-Furnace-Filter-MEGA-THREAD (https://forums.beyond.ca/threads/411253-Furnace-Filter-MEGA-THREAD/page4)

[Darell_n]

My mid-efficiency furnace also gets weird harmonic noises occasionally that is equal throughout the house. It is 100% the metal louvres in my return air grills. Sometimes they start humming and need to be bent a little or pulled out if the kids have hit them with something.

[?????]

Returns are quiet; vents are making the noise. I think the furnace is also making the noise but I can't tell for certain when I'm right on top of it

However, what i found is that if I remove the filter and leave the front furnace door open (which exposes the wires, etc.) the noise is like 99% reduced. If you strain you can still make some resonance out, but just barely.

Maybe it's not a furnace issue but some type of ducting/air-flow issue? Not enough/too much air based on existing duct sizing?


My mid-efficiency furnace also gets weird harmonic noises occasionally that is equal throughout the house. It is 100% the metal louvres in my return air grills. Sometimes they start humming and need to be bent a little or pulled out if the kids have hit them with something.

That was my issue with a couple air return ducts closest to the furnace.
For years they sounded like a turbine engine and I thought it was "normal" until one day I made contact with the grill and the noise went away.

I've just place a magnet strip on the back side of the grill to stop the vibration and it fixed the issue.

[SilverRex]

Not sure if this helps anything but I replaced my 24 year old carrier furnace last month with a stage 2 goodman, the old furnace was crazy loud when trying to start, and I had to replace it because one of the heat exchange cracked. Anyways the new furnace is so quiet I can hardly hear anything. Not sure if this is because I was so use to the old one which was loud.

[ExtraSlow]

The "digital" motors are a lot quieter on startup than the old school type. See my furnace fan motor discussion for details.

[g-m]

Not helpful but my plumber said try to avoid going high efficiency as much as you possibly can because they suck and break way more often. He also agreed with using mid to low filtration filters and definitely avoid high filtration

[Maxt]

Measure your return air size and read in the installation manual to see if it meets the spec for the size of the furnace. Also buy a bucket of duct sealer and go to town on all the joints.
On some furnaces, you have to redo the return airs to a dual inlet to a prefabbed return box that the new furnace sits on to get the airflow the machine wants at full tilt.
I've observed that some companies use silver silicone to seal ducts, then when one edge of it comes free it becomes a noise maker like a kazoo.
I may as well add that it's important to check the grading of the furnace, there are some models that can have premature heat exchanger failure if the furnace is tilted towards the back, since condensate won't drain totally from exchanger when the drain pan is at the front of the furnace.

[M.alex]

Measure your return air size and read in the installation manual to see if it meets the spec for the size of the furnace. Also buy a bucket of duct sealer and go to town on all the joints.
On some furnaces, you have to redo the return airs to a dual inlet to a prefabbed return box that the new furnace sits on to get the airflow the machine wants at full tilt.
I've observed that some companies use silver silicone to seal ducts, then when one edge of it comes free it becomes a noise maker like a kazoo.
I may as well add that it's important to check the grading of the furnace, there are some models that can have premature heat exchanger failure if the furnace is tilted towards the back, since condensate won't drain totally from exchanger when the drain pan is at the front of the furnace.

can you elaborate on the prefabbed air return box? my furnaces are just on the ground using the return air system that was with the original furnaces (from like 1992). one comment i'd read previously is return air setups for old mid-efficiency furances could cause harmonic issues with new furnaces because of higher fan speeds.

I had the installer back again today (6th time in a month, but at least it's free under warranty for whatever good that does) .... as usual this guy just ho'd and hum'd and looked at the filter. I demonstrated how opening the furnace door made the high pitched noise disappear and he's like 'yea, you're just dumping out a lot of air now, doesn't mean anything'.

Probably going to go find another company and pay out of pocket, but would like some ideas so I can speak to them first to see if they sound like they'd be wasting my time or not.

[M.alex]

Ended up installing new motors in both furnaces as the irritating noise went away. Defective Chinese junk right out of the box.

[ThePenIsMightier]

That's a lot better than it could've been.

[ExtraSlow]

What motors did you get and I assume that's all under warranty?

[ZenOps]

The harder the bearing the noisier it tends to be. Softer sometimes means you have to replace it more often.

Same thing supposedly goes for high performance brakes, imperfect and lower quality durability means that it doesn't squeak. Used to be true for gasoline too, add lead imperfection - no more knocking.

On a completely unrelated side note:

IV3dnLzthDA

The quest for quiet has had several roadbumps. There is no clear winner as some people can't hear high frequencies anyhow.

Could be the covids too, much like how it blocks taste, it seems to enhance tinnitus and ringing in the ears.

[M.alex]

What motors did you get and I assume that's all under warranty?

Whatever the Lennox furnaces came with from the factory - maybe the bearings were shot on the original ones out of the box, who knows, I'm just happy it solved my issue

[SilverRex]

not sure if anyone experienced this before when installing a brand new furnace, but after running smooth for 2 months, one morning it stopped working. As I go check it out, I noticed it tries to start but then stops. A couple of clicking sound and no ignition. The error code shows it is dL (idle) mode, so no alarm there. Finally had to call the installer back to check it out, he says the controller board was shorted and it blew the fuse on it. The first time he turned it back on shortly after replacing the fuse, it sparked and blew the fuse again. He looked at everything, an did not find any shorts or wires in the wrong places. Could explain what happen, but in the end, replacing the fuse one more time did the trick and it has been 2 weeks without any issues.

Just thought I share to see if this is just an unusual anomaly. or a common issue with new furnaces.

[Darell_n]

not sure if anyone experienced this before when installing a brand new furnace, but after running smooth for 2 months, one morning it stopped working. As I go check it out, I noticed it tries to start but then stops. A couple of clicking sound and no ignition. The error code shows it is dL (idle) mode, so no alarm there. Finally had to call the installer back to check it out, he says the controller board was shorted and it blew the fuse on it. The first time he turned it back on shortly after replacing the fuse, it sparked and blew the fuse again. He looked at everything, an did not find any shorts or wires in the wrong places. Could explain what happen, but in the end, replacing the fuse one more time did the trick and it has been 2 weeks without any issues.

Just thought I share to see if this is just an unusual anomaly. or a common issue with new furnaces.

I wouldn’t harbour any hope it’s going to stay running for any length of time.

[ExtraSlow]

All these furnaces seem horrible for reliability. I would suggest everyone have alternate means of heating your home in an emergency. I keep two of the 1500W electric heaters and figure those plus two gas fireplaces and a small section of heated flooring should get us through an emergency if we have one.

[ThePenIsMightier]

All these furnaces seem horrible for reliability. I would suggest everyone have alternate means of heating your home in an emergency. I keep two of the 1500W electric heaters and figure those plus two gas fireplaces and a small section of heated flooring should get us through an emergency if we have one.

That and the furnace repair biz you're about to buy...

[ExtraSlow]

That as well.

[ZenOps]

If the furnace is only slightly annoying, it might be worth it to just sound deaden the room with something like Sonopanels. Roughly the same cost as an expensive gypsum board, but can't be painted over, which usually isn't a problem for basement utility rooms.

Also, you can wire up your furnace to accept a battery backup (to run the fan)

1JNuovFpCpQ I'm sure it would be possible to manufacture a much less jenky solution. Useful if you think the power grid in your area will fail more often than the furnace itself.

[ZenOps]

BTW: I find my furnace also makes a high pitched squeal. But knowing the startup sequence, its definitely coming off the natgas valve. Seems more pronounced on cold days.