Noisy Rheem - http://www.hvacmechanic.com/ Forums
Original message
| NMFlyer
 |  "Noisy Rheem"
, posted Thu 17 Nov 12:45  
I purchased an 1150 sq foot home heated with a Rheem Criterion II.
The heater seems to work fine but the intake charge is Very loud. Is there a way to slow the motor speed to take the edge off of the noise?. Are there any other tricks for making the intake charge quieter on this furnace?.
KW
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Replies:
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| iceman9795
| "Re(1):Noisy Rheem" , posted Fri 18 Nov 00:44
If your unit has a variable speed motor(ECM) you need to check and make sure all of your vents are open, these ECM motors are able to calculate their cfm by load on the motor and will adjust the speed accordingly to move the proper cfm. if you close off any supply vents the motor will automatically speed up to compensate for the reduction in air flow by pushing more air through the grills that are open. or it could be a bad duct design, but it sounds like you have a restriction in your airflow somewhere.
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| Tech One
| "Re(1):Noisy Rheem" , posted Thu 17 Nov 14:05
If it's a whistling noise, and your filter is clean, It may be from high volocity air and the return air duct is to small. Do not change the blower speed unless you know what the CFM requirements are.
Tech 1
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| | nmflyer
| "Re(2):Noisy Rheem" , posted Thu 17 Nov 15:08
The filter is new and clean. It is not a whisteling noise, just loud air noise.
The return duct is 25 x 16 (the same size as the intake port on the side of the furnace). It is only about a 18" duct run from the furnace side to the room return air intake grate.
In fact, there is a second return air port that is a 16" insulated duct, about 14 feet long.
This is the noisiest intake I have ever heard.
The reason I ask about the motor speed is because all I can find on line says it has a variable speed motor. Unfortunately the manual or instructions did not come with the home.
Thanks KW
KW
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| | Freon
| "Re(3):Noisy Rheem" , posted Thu 17 Nov 15:54
Your problem is common. The noise you hear is vibration and blower noise conducted through both the air in the return duct and the walls of the return duct. Your solution is to stop the vibration/motor noise as much as you can. The best way is to insert a section of flexduct that is in a U shape. Since the furnace is so close th the return grille, you can afford a long section of flexduct. Also rubber pads under the furnace will help if some noise is conducted through the wooden floor.
Changing the motor speed is an option but only after you research the air flow associated with each speed. If the blower motor is going too slow, not only will some of the supply registers have negligeble air coming from them but the heat exchanger will age more quickly due to excessive heat. The proper air flow is determined by measuring the difference in temperature of incoming and exiting air. The range for this rise is printed on the furnace data plate. However you should check what speed the motor is set to. Usually (emphasis on usually) the high speed is for AC and medium is for heat. Again, temperature rise is the ultimate test for the proper blower motor speed.
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| | nmflyer
| "Re(4):Noisy Rheem" , posted Thu 17 Nov 16:04
Thanks, I only have about 5" between the furnace side and the wall. That specific wall is over a foot thick and contains the intake plenum. Because of that I'd have to remove the whole heater system to change the return air duct.
As far as the motor goes, I understand your point. What I don't know is how to determine what the motor is currently set on or how to change it. (keep in mind, I don't have the manual). The temp chart you mentioned is on the furnace panel and I can check that.
I have a feeling that it was default set to HI. This unit has no associated air conditioning with it. It is a small home and IF I can slow the motor speed down a bit and stay within the specs on the chart, I'll try it. I just have no info on how to accomplish that task.
Is there a place to get an online manual, or does anyone have the info I need?...
Thanks again. KW
KW
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| | shank
| "Re(5):Noisy Rheem" , posted Thu 17 Nov 21:35
Post the model number of the unit, and I can get you the manual.
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| | Freon
| "Re(5):Noisy Rheem" , posted Thu 17 Nov 17:39
What are the colors of all the wires coming from the motor? I'm sure a tech here will know which lead is for what speed. Usually, on simple, older motors, black is high, blue or brown medium/medium high and red low. But things change... wait for definitive information.
As to the vibration problem, you can try and cut a 2" slice from the return duct and use a rubber coupling. That will help eliminate the noise transmission through the duct walls. You might consider baffles placed inside the duct but those would be dependent on not restricting air flow too much. Lining the ducts with acoustical tile should also help, especially at bends in the ducting.
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| | nmflyer
| "Re(6):Noisy Rheem" , posted Fri 18 Nov 09:37
Freon, good advice on quietening down the duct... Ill try some of that. Not sure I have room to get in there and put in a flex joint, but Im sure that would help. The accoustic tile idea is a new one, but it makes a lot of accoustic sense.
Ill go look at the motor today and see if I can get the wire colors and routing.
The Model is RGPH-07EHUER SN # FD5D302F59926448
THanks for the help ... KW
KW
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| | shank
| "Re(7):Noisy Rheem" , posted Fri 18 Nov 13:23
You should have mail.
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