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How do I change the fan speed on my Rheem Classic 90 plus 45k btu heating system

How do I change the fan speed on my Rheem Classic 90 plus 45k btu heating system


  #1  
Old 10-29-12, 01:54 PM
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How do I change the fan speed on my Rheem Classic 90 plus 45k btu heating system

Well my title says it all. I have a Rheem Classic 90 plus burning propane. I know it has 4 fan speeds with the fastest putting out 1400 cfm and slowest around 900 cfm. It's pretty loud as it is and I know that I just have to change a couple wires on the the control board and I know It has to do with the connections marked W W. I understand the idea of the fan having 4 wires for 4 speeds but why are they all connected to the control board? For the lowest speed how should they be connected? Thanks for any input...
 
  #2  
Old 10-29-12, 02:36 PM
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I would recommend against making a change in the fan speed, since that can cause the furnace to run too hot or too cold.

The fan speed needs to be adjusted to stay within the heat rise specified on the rating plate of the furnace.

"Pretty loud" is a vague term. You might have a problem with the fan or motor, or you might not.
 
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Old 10-29-12, 04:53 PM
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Thanks for responding SeattlePioneer. I had my system checked out by a tech before running it for the season and the heat rise was right in the middle of it's range. I know to check the heat rise after making any changes "recomended in the manual". Besides there is a circuit that will shut the system down if the heat exchanger gets too hot.
 
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Old 10-29-12, 06:55 PM
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The limit will only shut the furnace down if the supply air is 10+F greater than the maximum on the rating plate.

The temp rise is right where it should be so the blower speed shouldn't be adjusted.
 
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Old 10-29-12, 06:59 PM
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why are they all connected to the control board? For the lowest speed how should they be connected?

Read more: http://www.doityourself.com/forum/ga...#ixzz2AkAJ02um
A separate speed is used for a/c if you have it.

The unused leads are normally connected to dummy terminals.
 
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Old 11-02-12, 08:06 PM
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Thanks Muggle. We don't have a/c. Dummy taps eh. Makes sence.
 
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Old 11-03-12, 03:35 PM
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Ok the yellow is for medium lo fan speed and it's on M1. So do I just have to swap it with the wire for lo speed? The other wires are on terminals labeled-heat cool fan etc. Do these terminals control fan speed at the various stages of the heating cycle?
 
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Old 11-11-12, 07:56 PM
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Bump. Any one have any more advice?
 
 

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