Rheem Criterion II Blower Noise


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Old 10-30-09, 11:25 AM
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Rheem Criterion II Blower Noise

Subject furnace has developed a whistling sound when the blower runs on heat or cool. Sometimes there is no sound. It doesn't seem dependent on how long the blower has run. Also the blower seems to run too fast & the resulting air noise through the registers is annoying. The house has 4 bedrooms, one story in CA. Two of the bedrooms are shut off. The blower motor connections to the circuit board are: Red-Heat, Blue-Fan, Yellow-M2. Any idea how to quiet this monster?
 
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Old 10-30-09, 01:35 PM
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You are describing a furnace that has a high static pressure due to an inability to circulate air properly through the ductwork. That could be because of a plugged filter, collapsed or damaged duct someplace, fan speed set too high, too powerful a motor, return air vent too small or covered over or too many warm air vents closed.
 
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Old 10-31-09, 12:10 PM
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Rheem Criterion II

Vents have all been opened & filter cleaned. Ductwork not checked. The blower motor speed has been changed from med/low (factory) to low. Whistling is still there. The furnace is 100,000BTU for a typical 4 bedroom CA home with 2 rooms not used. Think blower moter is 3/4hp. When installed 8 years ago we were disappointed how loud it was (& is) & how much faster the hot air came out of the vents. At that time there was no whistling but the overall furnace noise much louder than the old furnace & the air from the vents were moving curtains & blinds. Installer said that was because new furnace was much more efficient than the old one! I wish the Rheem blower motor could safely be slowed down in order to provide a slower delivery of heat. The furnace heats quickly but at the expense of noise at the furnace (rumbling, whistling) and too high speed hot air at the vents. Guess I have a racehorse instead of a plow horse.
 
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Old 10-31-09, 02:51 PM
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What makes you think there is a 3/4 hp fan motor on the furnace? A common horsepower rating for a 100,000 BTU furnace would be 1/4 to 1/3 HP.

Furnaces have the static pressure listed on the rating plate. That's the maximum difference in static pressure between the air coming into the furnace and the air going out.

Too much static pressure differential and you can cool off the furnace too much, as well as creating too high velocities through the ductwork. Or the ductwork could be too small, damaged or whatever.

Sounds like you need to find a GOOD repairman who has a monometer and knows how to use it to analyze problems with the furnace fan and ductwork of the kind you describe.

A competent person should be able to diagnose the problem accurately in one trip and give you good ideas on how to correct the problem.

It's possible the whole furnace is significantly oversized for your house.
 
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Old 11-01-09, 08:44 AM
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Rheem Criterion II

This furnace is 100M RGPH-10NBRJR and the spec sheet lists 3/4hp for the blower motor (also on the motor nameplate). This morning when the furnace turned on the whistling was quite noticeable but after 3 cycles heating the noise disappeared. The noise can also be heard in cool mode with just the blower running. How is the best way to find a good furnace person? Appreciate your comments.
 
 

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