Furnace making funny noise

[check]

Hi, Folks, I need to identify a noise that my high efficiency propane furnace is making, and I am hoping some of you have heard this before. The supposedly experienced service guy could not tell what it was, and so he just "guessed" it was the ($800!) fan motor.

It is a Payne Model PG96VAT48080 furnace, installed in August of 2013, and has worked fine up until now. But just recently, every once in a while there would be this strange kind of buzzing/honing sound when the fan was going full blast (e.g, on AC).

Here is a video link:

IMG 1884 - YouTube

It is very intermittent, and seems to only come on when the fan is on high.

Any ideas, my fellow TBNers?

James

 

[Diggin It]

No tube here, but from your description, maybe a fan bearing. Maybe an obstruction that gets drawn in with the higher airflow?


My refrig/freezer sounds weird sometimes. Finally figured out it wasn't defrosting properly and frost buildup would encroach on the fan blades at times.

 

[radios1]

you're getting ripped big time if he wants $800 for a fan motor, the video has no audio, but it has to be a worn fan motor, that's the only thing that moves!..

 

[grsthegreat]

Most of Those newer units use a dc inverter fan, variables speed. There spendy but not $800. Get part number and hit ebay. I replaced mine years ago....was less than $200 and took 10 minutes.

The compressor fan on my monagram built in fridge was failing. GE repair wanted nearly a grand to repair it. I got motor on ebay, direct OEM, for $90, took about an hour to install. Never did one before. Fridge works like brand new. No noise.

 

[Sigarms]

you're getting ripped big time if he wants $800 for a fan motor, the video has no audio, but it has to be a worn fan motor, that's the only thing that moves!..

First need to determine correct terminolgy from the OP. There is a difference between a fan motor for exhuast and a blower motor. For $800 I'm guessing it's the blower motor (added the fact that the exhuast fan motor really shouldn't have an affect on running the AC, but the blower motor would).

I installed my 80% variable speed gas furnace with a heat pump in my attic around 2004. Last year my blower motor went out. One of my few work perks is I buy directly from the manufacturer. As noted, I believe what the OP is refering to is the blower motor. My cost on that variable speed constant airflow ECM motor was WELL over 50% of the cost of what the OP was quoted (and my luck, it was past the 10 year parts warranty). If he gets it installed for $800, he wouldn't get ripped off IMO. As far as moving parts, need to look at the blower housing assembly as well, which includes the blower wheel).

Customers expectations are that if the unit is making a noise and it's diagnoised at being the blower motor, if the motor is replaced and the furnace is still making the same noise, the contractor should make it right and fix the "real" issue at no charge.

That said, if the gas furnace was installed in 2013 and it was registered, it should have a 10 year parts warranty, which means ANY part would be free, but the OP would still have to pay the labor to change it out. Since it was installed in 2013, not certain why it wouldn't have a 10 year parts warranty?

Carrier came out with on of the first variable speed ECM motors in the 1990's. Cost back then for the motor was about what I paid for mine in 2019 (20 years later). When I first saw the cost of the motor (not what the contractor pays for it) I remember joking to a guy back then that "dang, the cost of this new motor costs only a little less than a complete new gas furnace."

Due to FER regulations, PSC driven gas furnaces are no longer being made (those are the "cheap" permanent split capacitor motors that you could buy all day long for under $120 at supply houses). Every furnace now being produced (including electric mobile home "furnaces") now have at least the much higher priced constant torque ECM motor (AKA the X-13 back in the day LOL).

FER Standards Require Electronically Commutated Motors | 218-1-29 | ACHRNEWS

On a sidenote, we can thank California for the higher priced blower motors. Still more stuff coming down the pipe in the next couple of years due to that wonderful state.

 

[check]

First need to determine correct terminolgy from the OP. There is a difference between a fan motor for exhuast and a blower motor. For $800 I'm guessing it's the blower motor (added the fact that the exhuast fan motor really shouldn't have an affect on running the AC, but the blower motor would).

I installed my 80% variable speed gas furnace with a heat pump in my attic around 2004. Last year my blower motor went out. One of my few work perks is I buy directly from the manufacturer. As noted, I believe what the OP is refering to is the blower motor. My cost on that variable speed constant airflow ECM motor was WELL over 50% of the cost of what the OP was quoted (and my luck, it was past the 10 year parts warranty). If he gets it installed for $800, he wouldn't get ripped off IMO. As far as moving parts, need to look at the blower housing assembly as well, which includes the blower wheel).

Customers expectations are that if the unit is making a noise and it's diagnoised at being the blower motor, if the motor is replaced and the furnace is still making the same noise, the contractor should make it right and fix the "real" issue at no charge.

That said, if the gas furnace was installed in 2013 and it was registered, it should have a 10 year parts warranty, which means ANY part would be free, but the OP would still have to pay the labor to change it out. Since it was installed in 2013, not certain why it wouldn't have a 10 year parts warranty?

Carrier came out with on of the first variable speed ECM motors in the 1990's. Cost back then for the motor was about what I paid for mine in 2019 (20 years later). When I first saw the cost of the motor (not what the contractor pays for it) I remember joking to a guy back then that "dang, the cost of this new motor costs only a little less than a complete new gas furnace."

Due to FER regulations, PSC driven gas furnaces are no longer being made (those are the "cheap" permanent split capacitor motors that you could buy all day long for under $120 at supply houses). Every furnace now being produced (including electric mobile home "furnaces") now have at least the much higher priced constant torque ECM motor (AKA the X-13 back in the day LOL).

FER Standards Require Electronically Commutated Motors | 218-1-29 | ACHRNEWS

On a sidenote, we can thank California for the higher priced blower motors. Still more stuff coming down the pipe in the next couple of years due to that wonderful state.

Thanks, Sigarms, I am pretty sure it is the blower motor that the HVAC guys wanted to replace. And yes, it normally costs about $817, but is covered (parts only) under the 10-year warranty. However, the labour is some $500 to install it. I also sent a note to Payne with the video in case their people know what the cause is. Frankly, I am surprised that no one recognizes this sound - it is very distinctive. And it is VERY intermittent. One theory was that the cause was a hi-test, high efficiency, HEPA furnace filter, which apparently restricts the airflow quite a bit, making the
blower work extra hard to get the necessary volume of air flow. So I put in a cheap filter, and things were fine for a while. Just recently, however, it happened again while the AC was on and the blower was on high (which the furnace itself determines), and this time it did not stop when I put a new (cheap) filter in.

 

[Sigarms]

Thanks, Sigarms, I am pretty sure it is the blower motor that the HVAC guys wanted to replace. And yes, it normally costs about $817, but is covered (parts only) under the 10-year warranty. However, the labour is some $500 to install it. I also sent a note to Payne with the video in case their people know what the cause is. Frankly, I am surprised that no one recognizes this sound - it is very distinctive. And it is VERY intermittent. One theory was that the cause was a hi-test, high efficiency, HEPA furnace filter, which apparently restricts the airflow quite a bit, making the
blower work extra hard to get the necessary volume of air flow. So I put in a cheap filter, and things were fine for a while. Just recently, however, it happened again while the AC was on and the blower was on high (which the furnace itself determines), and this time it did not stop when I put a new (cheap) filter in.

Honestly, I didn't watch the video. Ok I just did now LMAO. Sounds like the motor, but was the blower wheel and shaft looked at as well?

$800 for a variable speed constant air flow ECM motor is pretty much the norm.

I hate to say this, but $500 isn't too bad of a price for labor for that kind of motor. A good HVAC contractor/company will give you one year labor on the warranty part IMO. Meaning if you spend $500, you know it's fixed for at least a year with no more money coming out of your pocket if the service work performed doesn't eliminate the original issue). Good contractors will also offer you a service agreement, and a good business practice is to offer discounts on any labor work because you have a service agreement with them. That said, at $80 for a service call, 3 quotes is still costing you $240, but you could call different companies to see what they offer and what they charge for service work.

If a guy is going to charge you $500 for labor to replace the motor, he should of looked at everything to ensure that this is the actual issue and it's not a question of what the best odds are as when I watched the video. I'm behind a computer, I didn't take the time to come to your house. Better service techs will video what they take appart and show the homeowner the issue. Did you take the video or the did the service guy? If you took the video, I'd drop the guy that came out because you're doing more work than him. Ultimately, good companies who do good work and communicate clearly with their customers are not the cheapest.

However, considering the motor type and filter "change up" you mentioned, any decent service tech should be noting the static pressure along with CFM's (and give you a copy for your records as well). Your furnace installation instructions has a blower table along with allowable static pressure along with allowable CFM's (reason why proper ductwork sizing is important if a new system is being installed).

By collecting this data (SP and CFM's), it will let you know exactly how much "strain" a certain type of filter is having on the system for certain. This is why this kind of data is important with that kind of motor IMO. Without knowing the size of the ductwork, it's possible even a standard 1" poly filter could be running higher than normal static pressure. 7 years for a blower motor isn't unheard of, but I'd want to make certain the ductwork system isn't straining it. By doing this basic work of measuring SP and airflow, it's not a theory of what could be wrong, it will tell you for a fact either way of what is the issue of premature failure.

The "magic" number on a good static pressure is a .50 with around 340-400 CFM's per ton (I would guess anything over a .85-.90 will cause premature failure on your type of motor). The reason why you measure both SP and CFM is because some guys will lower the fan speed to decrease the SP. Only problem is if you aren't hitting you're CFM's by lowering the fan speed, you can kill the compressor (checking actual CFM's the system is producing will verify this). Guys always want to jump to gauges first for readings on AC issues, but without verifying air flow and SP first, your refrigerant readings could be off without even knowing the real reason. Old instructor always use to say know your A,B,C's (airflow before charge).

FYI, Payne and Carrier are made at the same plants. Same company, different marketing.

Ironically enough, the cheaper PSC blower motors were more immune to higher static pressure issues than the much more higher priced variable speed constant air flow ECM motors (I've seen 1.2 SP have a constant negative affect on PSC motors as well, which would kill your type motor rather quickly). So what's the US government do? Make it illegal for manufacturers to use PSC motors now in their new furnaces.

 

[kenmac]

So what's the US government do? Make it illegal for manufacturers to use PSC motors now in their new furnaces. The reality is at the end of the day, I'm not certain if we're really saving money.

You can always count on the Government to mandate what's best for the peasants !

 

[Sigarms]

You can always count on the Government to mandate what's best for the peasants !

Just be glad you're out.

Part of what's coming down the pike by our federal government is static pressure and how it correlates to AHRI ratings.

Keep in mind, this won't affect service or retrofit equipment, but it will affect new installs with ductwork on new homes that are inspected.

 

[radios1]

ECM motor repair kits are cheap. ecm motor repair kit - Google Search now, if it needs new bearings, that can be done at a motor repair shop cheaply too!..