Rheem furnace dip switch adjust


  #1  
Old 01-23-19, 03:50 PM
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Rheem furnace dip switch adjust

Hello,



I have a sparkly clean new furnace with variable speed motor, but it doesnt seem to run on low speed often enough. It turns on and off pretty often, which usually means its sized too large. And it doesnt run on low speed enough.

So I wanted to try adjusting the dip switches. (My installer crew didnt even take off the protection covers to the dips, and he is not returning my calls anymore). I have a non communicating Thermostat(Honeywell T5 smart stat), so I have to adjust from the dips. From the instructions below, can anyone tell me what the numbers mean? +7f, -7f, 12f.... I REALLY dont understand the negative 7. If it has anything to do with how many degrees the stages run for, then neg 7 makes no sense. It would mean the furnace only turns on if the room temp goes down 7 degrees, but never if UP 7.



And if I prefer the low speed to be set at 12, what do I set the high speed at in order to balance?


We set the temps down near 60f at times, then up to 68 ish, and we are in NO hurry for it to get there. Below is from a manual. The bold text shows my question. Also attached chart. Any explanations will help, thx.

I. Low Gas Heat Rise (Airflow) Adjustment; S3-13,

S3-14

Two dipswitches (S3-13, S3-14) shall be used to

select low (1st stage) gas heat rise airflow adjustment

in legacy mode. Each selection will use a different

airflow demand for first stage gas heat. The

selections are set to approximate a specified temperature

rise as follows. Note: Temperature rise

will vary based on conditions and technician

should always check temperature rise.

S3-13 S3-14 Target Temperature Rise

OFF OFF Nominal Value Specified on Rating

Label (Factory Setting) (Approx.)

ON OFF Approx. +7F

OFF ON Approx. -7F

ON ON Approx. +12F


J. High Gas Heat Rise (Airflow) Adjustment; S3-

15, S3-16

Two dipswitches (S3-15, S3-16) shall be used to

select high (2nd stage) gas heat rise airflow adjustment

in legacy mode. Each selection will use a different

airflow demand for second stage gas heat.

The selections are set to approximate a specified

temperature rise as follows. Note: Temperature

rise will vary based on conditions and technician

should always check temperature rise.

S3-15 S3-16 Target Temperature Rise

OFF OFF Nominal Value Specified on Rating

Label (Factory Setting) (Approx.)

ON OFF Approx. +7F

OFF ON Approx. -7F

ON ON Approx. +12F
 
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  #2  
Old 01-30-19, 06:58 PM
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Well, I finally ran across this flyer which shows a cross reference in the last table so i could change the switches. https://cdn.globalimageserver.com/Fe...8-83BB4C60BCE0
It may have made a change to increase run time to the lower speed, but my Decibel meter only registers 2 to 3 decibels less at the lower fan speed. I still cant find any info or person who can tell me what this motor is really capable of or what a Rheem communicative Tstat would do differently, noting exact run times and decibel differences. Maybe consumer reports can do furnaces?
 
 

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