About stages in A/C


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Old 08-06-10, 04:15 PM
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About stages in A/C

I have just installed a new Amana 2 stage 16 SEERs A/C system, and have a few questions:
1) How to determine what stage is on currently ?
2) What conditions trigger to switch between stages?
3) How can I control the stage?
Thanks.
 
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Old 08-07-10, 09:07 PM
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Iam not sure what problem you are having but here is a run down of how a 2 stage system typically works.

There are typically 2 conditions that will cause your unit to go to 2nd stage
A. The set temp on your tstat is 2 degrees or more higher (for heat) or lower (for cool) than the room temp. This is a tstat controlled system
B. The air handler determines that the Compressor has been on a certain amount of time continuously in 1st stage say 10 minutes it will then step up into 2nd stage to satisfy the call. This is a Air Handler controlled system.

You will need to determine how your installer set your system up some installers use a cheapo single stage tstat and let the air handler determine second stage. I have actually seen some systems where the jack legs did not even hook up the 2nd stage wiring on a nice 2 stage tstat (due to not enough wires and no desire to pull a new wire I guess) and they also did not set the dip switches correctly for the ECM motor. I prefer a proper 2 stage tstat and let it take care of all staging calls. I have recently installed a 4 stage heat and 2 stage cool Frigidaire unit at my own crib here. I use the Honeywell 9421 tstat with the equipment interface module to take car of the controls I am very pleased with the setup so far. After that install I can certainly understand how easily a installer can mess up a controls system on one of these highly complex units. It appears that there are 4 critical areas. Tstat selection/Tstat setup/Tstat wiring/Unit dip switches etc. if a man messes up on any one there will be problems with the unit.
 
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Old 08-08-10, 03:04 AM
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Originally Posted by Former Member

There are typically 2 conditions that will cause your unit to go to 2nd stage

B. The air handler determines that the Compressor has been on a certain amount of time continuously in 1st stage say 10 minutes it will then step up into 2nd stage to satisfy the call. This is a Air Handler controlled system.
I've not seen of heard of this type of set up on a two stage cooling, just in gas heat set up.

As said before, depends on what kind of stat is there.

If you have a basic or older stat, there will be a "swing", and some people can feel that 2˚ change. Where "smart" stat like honeywell, will not have the swing, they will cycle 2nd stage on as needed to help keep the temp in check.

Long run time is normal for two stage system, and it's not using more powere on this set up.
 
 

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