# What is the correct blower speed setting?



## beenthere (Oct 11, 2008)

Set it to the speed that the temp coming out of the furnace in heating is 55° warmer then coming into the furnace.
Use same speed for both heating and cooling.

Measure temps at return plenums.


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## Samber (Jun 17, 2010)

Thanks for the reply! The temperature rise range for the furnace is 25 to 55, so is it correct to aim for 55?

Also, there are two different connections for heating and cooling, so I can't use the same speed for both, unless I changed it in the winter.

Is it ok to run the furnace in the summer?

Thanks!


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## beenthere (Oct 11, 2008)

Shoot for 40 to 45 then.

Need a twinning/doubling connector to run both heating and cooling at the same speed.

You can run a gas furnace in the summer. Doesn't hurt anything. Just heats up the house a little faster then in winter.


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## Samber (Jun 17, 2010)

Ok, so if I get the heating split correct that will be the correct cooling CFM as well?

Also, the circuit board has four terminals: Heat, Cool, M1, and M2. The two speed setting wires that are not hooked up to heat or cool are on M1 and M2. Is it ok to hook any of the speed wires to either Heat, Cool, M1, or M2?


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## beenthere (Oct 11, 2008)

M1 and 2 are park terminals. Thats where you put the unused speed wires. So they don't dangle and get drawn into the blower.

If you have 2 speeds that get you close to the 45° rise, You can use the one that gets you the hire temp as your cooling speed.
The blower at a 45° rise will be moving about 800CFM. For your 1.5 ton it should be a bit less though.

Check the temp rise at all speeds and post back what they are. And I can tell you which ones are best for heat or cooling.
Often on small furnaces though, the same speed works out best for both heating and cooling.


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## [email protected] (Jul 19, 2020)

Is the twinning/doubling connector that you mention to run both cooling and heating at the same fan speed just a Y in the wiring with a proper connectors on the end? When in “fan only” mode how is the speed selected? 

I have a Rheem model RGRA 07EMAES. 
Thanks
Jeff


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## beenthere (Oct 11, 2008)




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