New Trane S9X1 inducer high pitched noise. Is this normal?

[Morac]

I had a 25+ year old HVAC system replaced a couple of days ago with a Trane S9X1B040U3PSBAB HVAC. I don’t know the model of the old unit, but it was so old it had a passive hood venting system and apparently didn’t use fuses.


The new unit is installed in a hallway closet on my second floor near my bedroom. When the old unit was running I barely heard anything in my bedroom with the door open and not at all with it closed. The new unit makes a high pitch noise that’s audible not only from my bedroom with the door closed, but on the first floor of the house (townhome). That’s a good 30 feet away through the (vented) closet door of the utility closet.


The person who installed it said it was the inducer motor (something my old system didn’t have) and he didn’t seem to think it was unusual. Though we didn’t run the heat that long since it was hot that day and it was late by the time he got the HVAC working. I’ve read that inducer motors do have a higher pitch and can be heard, but from what I’ve read they shouldn’t be loud enough to hear several rooms away. It’s louder than both the blower and the burner and can easily be heard over both. I think it woke me up this morning.

I tried putting my hand on the furnace and the PVC pipe to see if maybe that would quiet the noise, but it didn’t. I did fell vibrations in the pipe though.

I spoke to the owner of the company that installed the furnace and played him a recording and he said it sounded normal, but he’d have some one check it out. I’m still waiting on that, but considering the installer didn’t think it sounded unusual, I don’t have much hope another guy will either.

While not exactly the same, the closest I’ve found to the sound it makes is this video of a Trane XR95. I can’t post links, but it’s a YouTube video with a video ID of 9YpEfcbXKMI.

Is the guy right? Is this normal? If so is there a way to quiet it or soundproof the closet?
If not what could be the cause?

[mgenius33]

First, don't sound proof the closet without knowing what type of venting system you have. If it's non-direct vent, that means you're drawing combustion air from the closet space. If that closet is too tight it will not work properly. If it's direct vent, meaning you have intake and exhaust pipes, then you should be ok. I would check with your installer first though.

Depending upon the flue pipe configuration it could be moving too much combustion air and causing it to whine. It may need to be checked with a combustion analyzer to ensure proper operation. High oxygen levels can be an indication of too much excess air.

If all is in order, have them replace the motor assembly. It's under warranty and a quick fix. Probably take longer to diagnose than it would be to replace it. I have 2 Trane furnaces, and can barely hear the inducer motor standing a couple feet away from the unit. My bet is flue configuration. How, many pipes, how long are the pipes, and how many bends do they make?

[Morac]

The new system is using direct vent I believe as part of the process for the entire installation was weatherizing/sealing the attic and they told me they needed to run 2 sets up pipes up through the roof to suck in and blow out air. The pipe on the right goes up to a 45 degree elbow joint which then connects to another pipe that goes up an existing hole in the ceiling into the attic. The pipe on the left goes straight up through a new hole. Both are labeled “7200 2” PVC Type 1”.

I don’t know how long the pipes are. They go up through the attic out to the roof into a boot where they then turn down to keep out the rain. At least that’s what I was told. The attic is high enough to stand in near the center where the pipes are, so I’d guess maybe 10 to 20 feet total length per pipe. For bends I’d say 1 for the left one and 2 for the right.

They also installed a tankless water heater in the same closet that also has 2 pipes going straight up and I’m assuming it also has an induction motor. That one doesn’t make a high pitch noise. It sounds more like a white noise machine.

There’s also a washer and dryer in the closet. I haven’t tested whether either would drown out the inducer motor noise.

Listening to everything today, I’m not sure the inducer is louder per say or that it’s just more noticeable and carries further because of the pitch. I measured about 54 dB in the closet using an iPhone app. I can hear the blower from downstairs if I listen for it, though I’m not sure if that’s through the vents or not. It’s not really noticeable probably because I’m used to it. The inducer I can just hear any time it kicks on and many times I hear it over other things making noise like the TV. I don’t hear it if I go down into the basement.

[Morac]

The people came to fix some other issues and they told me the sound it’s making is normal for my model. One guy told me he’s installed hundreds of the units and that’s what they sound like. I still don’t think it sounds right, especially for a brand new unit.

Unrelated to this, the installation manual says the circuit board takes a 5 amp fuse and the people who installed the board put in a 3 amp. The fuse blew when I tried to have an Ecobee installed and they blamed the Ecobee, but now I’m wondering if it was because the fuse should be a 5 amp. I’m assuming the manual is correct.

[pecmsg]

The people came to fix some other issues and they told me the sound it’s making is normal for my model. One guy told me he’s installed hundreds of the units and that’s what they sound like. I still don’t think it sounds right, especially for a brand new unit.

Unrelated to this, the installation manual says the circuit board takes a 5 amp fuse and the people who installed the board put in a 3 amp. The fuse blew when I tried to have an Ecobee installed and they blamed the Ecobee, but now I’m wondering if it was because the fuse should be a 5 amp. I’m assuming the manual is correct.

Time too get another contractor too review the entire install!

Was a start up and commissioning report filled out and a copy given to you?
War a combustion analysis performed as required by the manufacture? A copy should be attached to the furnace.

[mgenius33]

The people came to fix some other issues and they told me the sound it’s making is normal for my model. One guy told me he’s installed hundreds of the units and that’s what they sound like. I still don’t think it sounds right, especially for a brand new unit.

Unrelated to this, the installation manual says the circuit board takes a 5 amp fuse and the people who installed the board put in a 3 amp. The fuse blew when I tried to have an Ecobee installed and they blamed the Ecobee, but now I’m wondering if it was because the fuse should be a 5 amp. I’m assuming the manual is correct.

The fuse is fine. The total current should be well under 3A, more than likely Ecobee was installed without turning off power or some wires were crossed somewhere. If it's the factory installed transformer it's likely a 35VA which would have far less max current than 3A. The 5A fuse is maximum. Again, the transformer can't even handle 3A let alone 5.
I don't like the blow off, eh that's how they all sound. Those units should be relatively quiet. I don't sell many S9X units, I typically do the S9V models, but they're usually quiet. If not, I would be ordering another one, and if the new one made noise, I'd be on the phone with tech support until there is a proper fix.
The equipment needs to be verified that the inducer is not drawing too much current. There's a possibility it may need some type of electronic noise filter or something. All that said, I don't know what you mean by noise as all people have different sensitivities to different frequencies. To me white noise is more like a ssscccchhhhh sound like a waterfall or something. It's not a high pitched whine like an old picture tube tv set. If you're used to an old 70% draft hood furnace, then yes you may notice a whirrrring sound from the new unit.

Sometimes, the fix is isolation. I remember an old gas pack that caused compressor vibration through first floor of the home. The compressor sounded quiet standing next to the unit, but inside the house it was much louder. We tried rubber pads under the whole unit, blower speeds, checked all the compressor readings. The fix.... a flexible gas connector. This isolated the rigid gas line connecting the house to the unit.

[Morac]

Sometimes, the fix is isolation. I remember an old gas pack that caused compressor vibration through first floor of the home. The compressor sounded quiet standing next to the unit, but inside the house it was much louder. We tried rubber pads under the whole unit, blower speeds, checked all the compressor readings. The fix.... a flexible gas connector. This isolated the rigid gas line connecting the house to the unit.

I realized I can hear the blower and furnace from downstairs too, I’m just used to that noise after 20 years I guess. I’m not used to the inducer’s pitch. I recorded the sound, but I can’t attach it here as it only allows photos. The pitch kind of sounds like a leaf trimmer.

The owner recommended I replace my louvered closet door with a solid door. He said the slots were needed for my old furnace to pull air in from the house, but aren’t needed for the new 90+% furnaces. I’m not sure that would completely get rid of the noise, but it would definitely help.

My main issue with a solid door is the room will still heat up as even if the furnace doesn’t leak heat, the ductwork and pipes will still radiate heat. Plus the dryer is in there, though I could leave the door open when the dryer is going.

[Morac]

Time too get another contractor too review the entire install!

Was a start up and commissioning report filled out and a copy given to you?
War a combustion analysis performed as required by the manufacture? A copy should be attached to the furnace.

I’m still waiting for some paperwork as the installation hasn’t even gone through inspection yet. I’m supposed to be mailed/emailed some things. I don’t see anything attached to either the HVAC or tankless water heater besides some stickers with the model #, warning labels, etc. The only other thing left was the installation/service guide.

I don’t think a combustion analysis was done. I don’t know what that is, but they left shortly after they got the thermostat working. I was told they are filing paperwork as part of the inspection (such as a door pressure test), so maybe they did and didn’t give me a copy.

The whole install was done as part of an energy home improvement plan where the house is weatherized and old equipment is replaced by energy efficient models. The install is paid partially by a rebate from the state (NJ) and the rest is with an interest free loan from my electric/gas company with me paying it off over 10 years. Getting another contractor to come out would require me to pay out of pocket. I suppose I could call Trane directly.

[pecmsg]

I’m still waiting for some paperwork as the installation hasn’t even gone through inspection yet. I’m supposed to be mailed/emailed some things. I don’t see anything attached to either the HVAC or tankless water heater besides some stickers with the model #, warning labels, etc. The only other thing left was the installation/service guide.

I don’t think a combustion analysis was done. I don’t know what that is, but they left shortly after they got the thermostat working. I was told they are filing paperwork as part of the inspection (such as a door pressure test), so maybe they did and didn’t give me a copy.

The whole install was done as part of an energy home improvement plan where the house is weatherized and old equipment is replaced by energy efficient models. The install is paid partially by a rebate from the state (NJ) and the rest is with an interest free loan from my electric/gas company with me paying it off over 10 years. Getting another contractor to come out would require me to pay out of pocket. I suppose I could call Trane directly.

And it's in your best interest to do it!

The contractor knows the #'s PSE&G are looking for and will just write them in, no measurements are taken. You will NOT have the energy savings you were promised, you need a second opinion

[mgenius33]

I don't think they necessarily did anything wrong per se, but going above and beyond what a typical contractor does makes them more of an elite contractor. Unfortunately, most people don't understand what goes into being an elite hvac contractor. Installation of an hvac system is not like installing a basic appliance like a refrigerator. It's not plug n play. Ducting modifications, and equipment adjustments more often than not, need to be made. Again, not saying there's anything wrong with the installation, but checking operation to ensure everything is within tolerance can help resolve some oddities. It could just be bad bearings in the inducer motor, or it could be as simple as a gas pressure adjustment. It's hard to tell over the internet.

One S9X1 I did install had a mis-programmed blower motor. It's supposed to have 9 speed adjustments. I could only get up to speed 5. Though the unit was factory set, I wasn't getting the temperature differential I wanted. Replaced the motor and voila, exactly what I wanted. I complained to tech support, and wouldn't you know, a couple months later there's a factory service bulletin. So, unless the elite contractors test the equipment for issues, the factory will continue producing something that could be a bit off. Would the factory blower speed have worked? Yeah, probably, but not the way that would deliver the performance I wanted.

[Morac]

I wanted to give an update on this.

I had told the original installers I wanted an existing (AprilAire) humidifier reattached, but because the condensate was in the way, there was no way to cut a return hole for the humidifier, so they never re-attached it and just left it attached to the ductwork, but removed everything else. This includes the water drain tube, without shutting off the water! The electro-mechanical switch was closed and power removed so the water wasn’t flowing, but still.

Any way, the same guy who came out and told me the inducer sounded normal was also out to remove the humidifier from the ductwork, patch the associated hole and remove the water piping. After he left, I noticed an additional whistling noise when the blower was going. I tracked that down to the air filter door not full closing because the filter wasn’t pushed in far enough.

I fixed that which not only got rid of the whistling, but also seemed to make the inducer quieter. That and/or sealing the duct helped.

I still hear it when the furnace kicks on, but it’s not as loud as as “whiny”.

[pecmsg]

I wanted to give an update on this.

I had told the original installers I wanted an existing (AprilAire) humidifier reattached, but because the condensate was in the way, there was no way to cut a return hole for the humidifier, so they never re-attached it and just left it attached to the ductwork, but removed everything else. This includes the water drain tube, without shutting off the water! The electro-mechanical switch was closed and power removed so the water wasn’t flowing, but still.

Any way, the same guy who came out and told me the inducer sounded normal was also out to remove the humidifier from the ductwork, patch the associated hole and remove the water piping. After he left, I noticed an additional whistling noise when the blower was going. I tracked that down to the air filter door not full closing because the filter wasn’t pushed in far enough.

I fixed that which not only got rid of the whistling, but also seemed to make the inducer quieter. That and/or sealing the duct helped.

I still hear it when the furnace kicks on, but it’s not as loud as as “whiny”.

More and more it sounds like oversized equipment on undersized ducts!

[Morac]

More and more it sounds like oversized equipment on undersized ducts!

I don’t feel like that’s it. My older furnace put out hotter air.

Anyway I have a new problem. The GFCI outlet that the condensate pump is plugged into tripped twice today. The first time I noticed because my heat stopped and the thermostat shut off because the pump cutoff tripped. The second time nothing was running, when I heard a pop and checked and it had tripped. The thermostat and furnace stayed on for that.

Since then it’s been okay. It was also okay yesterday.

During the time it tripped it was raining. I’ve had another GFCI trip during rain because it goes to the outside outlets, but this shouldn’t and none of the other ones in my house did.

One of my UPSes kick on because of a low voltage situation, but again no other GFCI tripped except the pump one.

The contractor thinks the GFCI is bad and is sending someone out Monday to replace it, but the rain makes me think over wise.

[pecmsg]

I don’t feel like that’s it. My older furnace put out hotter air.

Anyway I have a new problem. The GFCI outlet that the condensate pump is plugged into tripped twice today. The first time I noticed because my heat stopped and the thermostat shut off because the pump cutoff tripped. The second time nothing was running, when I heard a pop and checked and it had tripped. The thermostat and furnace stayed on for that.

Since then it’s been okay. It was also okay yesterday.

During the time it tripped it was raining. I’ve had another GFCI trip during rain because it goes to the outside outlets, but this shouldn’t and none of the other ones in my house did.

One of my UPSes kick on because of a low voltage situation, but again no other GFCI tripped except the pump one.

The contractor thinks the GFCI is bad and is sending someone out Monday to replace it, but the rain makes me think over wise.

Whistling with the door open is a major sign of return restrictions!
I wire my condensate pump safety to the A/C. If it fails during heat I’ll deal with the mess without shutting off the heat.