ReplyCould be the fan bent when trying to get it off a 30 year old motor. Hopefully they checked the rest of the furnace out very well and you don't need to put a bunch of money into what's the equivalent of a car with 800,000 miles.
Regular Guest
Need some opinions...
The blower motor in my nearly 30 year old Rheem Criterion recently died. We had the blower motor replaced with an OEM spec motor. Now when the heat kicks on there is a annoying humming or vibration noise coming from the unit. At first, I thought it was the washing machine running on spin cycle downstairs... Called the HVAC technician back out and now they are saying that the fan and possibly housing need to be replaced.
I don't mind having this stuff replaced if needed, but does this sound plausible? There was absolutely no sound, other than the sound of air coming out of the vents, prior to the motor dying. The technician is saying that with the unit being as old as it is, it isn't uncommon for the old fan to vibrate when a new motor is installed (new motor is spinning faster than the old one). For one, this was not stated prior to having the motor replaced. Had it been said that it is common for the fan to make noise when they installed this new motor, I would have gone ahead and replaced the fan as well to save on the labor. I also have a hard time believing this is the case... The fan is metal. Unless it was damaged when pulling the motor, I find it hard to believe that it has deteriorated over time and is now vibrating due to the new motor spinning faster than the old.
Professional Member*
Could be the fan bent when trying to get it off a 30 year old motor. Hopefully they checked the rest of the furnace out very well and you don't need to put a bunch of money into what's the equivalent of a car with 800,000 miles.
Global Moderator
It is possible that the replacement motor is not wired correctly. Another possibility is that the original motor was set for the incorrect speed but the new one IS on the correct speed.
Did the tech measure the temperature rise to ensure the new motor is on the appropriate speed?
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Professional Member*
Could be any # of things. What does the contractor say?
Regular Guest
Thanks for the replies. Not sure if the tech measured temp rise. The tech did say that neither motor is an ECM motor so they said they could not adjust the speed up/down.
Regular Guest
Tech said I needed to replace the fan and housing and the noise would go away.
Professional Member*
Maybe get a second opinion!Originally Posted by bcampbe7
Professional Member*
Some of those older Rheems/Ruuds had a 3/4 hp blower motor, even the 75,000 btu had the 3/4 hp motors. They could have had the original motor on a lower hp setting.
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"When the teachers become unteachable we're all in trouble" ~ Mr. Bill
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Professional Member*
Hard to believe unless it is a belt drive motor. Even then things can be done.
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Global Moderator
Baloney! Get a better tech.
*********
https://www.hvac20.com/ High efficiency equipment alone does not provide home comfort and efficiency. HVAC2.0 is a process for finding the real needs of the house and the occupants. Offer the customer a menu of work to address their problems and give them a probability of success.
Find contractors with specialized training in combustion analysis, residential system performance, air flow, and duct optimization https://www.myhomecomfort.org/
Professional Member*
Actually he probably just need a Tech not a Parts changer!
R I P Icemeister
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Regular Guest
Thanks for all of the help and ideas thus far.
Tech came back out today. This is the original tech that installed motor. The tech that came out on Friday was different. The tech today set fan to medium and told us to use thinner air filters. Even without a filter, the noise is still there, albeit a bit quieter since fan is now on low. Tech said that the fan was not damaged when he removed it from the old motor. He did say he is going to talk to his boss to see if he had any more ideas.
I am wondering if the new fan could be bad. I can’t see that being very probable though.
Professional Member*
Well I hope he is not a moron and just set the fan to a lower speed tap without testing the temperature rise.
Wow, I really hope.
Regular Guest
Not sure if they did or not... My guess is they didn't. They were only here for about 25 minutes and I have wireless thermostats that take a minute or two to boot up each time the power is shut off.
I just performed a temperature rise to the best of my abilities (watched YouTube to see where to perform temp readings) and this is what I get with my cheap equipment:
Temp just after A-coil - 91*F
Temp at return inside cabinet - 68*F
Thermostat was set to 72*F to get it to come on.
Not sure my method of performing a temperature rise test was valid. I also couldn't find the label that identified what the temp rise should be on this 1993 Rheem Criterion gas furnace.
Regular Guest
Wanted to circle back around on this issue and give an update.
More experienced tech came out and immediately said that the fan was spinning too high. He said with the age of the unit, finding the same RPM fan may have been difficult so they bought one close. He set the heat on LOW and the AC on MED/LOW. Temp rise test showed 34*F. Seems to be running better than ever. Heats the house up fast and you don't hear a thing.
Thanks for the help and guidance.
Professional Member*
Funny, my BS meter is ringing!
Temperature rise is one measurement but...………………. Were any air pressure measurements taken?
R I P Icemeister
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Regular Guest
Not that I know of... If it isn't obvious, I am no expert and do not know what an air pressure measurement would be or how that is done.
They didn't take any measurements in the living area of the house. I didn't go into the attic with them.
Professional Member*
Call them back and Ask what the T E S P readings were?
R I P Icemeister
Supporting our Vet’s
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Regular Guest
Is that something that should be done any time a blower motor is replaced?
Professional Member*
Of course it's not an ECM if it's 30 years old, but it could be a shaded pole if it's that old...
__________________________________________________ _______________________
“Experience is a hard teacher because she gives the test first, the lesson afterwards" ~ Vernon Law
"It's what you learn after you know it all that counts." ~ John Wooden
"When the teachers become unteachable we're all in trouble" ~ Mr. Bill
"Remember "Pro" is only a name, it's not always a mindset determined to do everything correctly" ~ Mr. Bill
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