Expected Temp and Humidity with AC?

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Old 06-27-14, 06:45 PM
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Expected Temp and Humidity with AC?

Just had a split 2 ton 16 seer AC system installed. Single speed compressor and multi speed AH. (Manually change speeds) It has a delay feature that lets the AH fan run a bit after the compressor shuts off.
What is the humidity level I should expect?
With outside temps of 90 degrees, and humidity of 85% - 90% during the day, our inside temp is 77 degrees and 55% humidity. We can make it cooler, but are comfortable at 77.
Just wondering if I should try lowering the AH fan, to get lower humidity. I would hope that if the lower fan speed lowered the humidity, that we would be able to set the thermostat at 78, and be as comfortable as at 77 degrees, with higher humidity. But not sure about that.
I assume the lower fan speed would require longer run times, and more $ to run.
So, do you think I should mess with the fan speed?
We had a single wall unit before (860 sf house) so don't have much to compare to.
Thanks for any advice.
 
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Old 06-27-14, 06:56 PM
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If you can turn off the blower off delay it would decrease the humidity in your home.

The water that has condensed on the evaporator coil will evaporate and go back into your home when the condenser turns off and the blower continues to run.
 
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Old 06-27-14, 07:17 PM
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Good point. I'll look into that. I thought it would save $ as it would still be cooling, without the cost of running the compressor. I guess everythings a trade off.
Would you do it if it was your system?
 
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Old 06-27-14, 07:32 PM
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Air conditioning control is often is a choice between efficiency and comfort.

I have that option with my Prestige thermostat as well but I do not want higher humidity in my home. I do not use the delayed fan off function.
 
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Old 06-28-14, 07:50 AM
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Your 2-Ton condenser is oversized, it would even be oversized at 1.5-Ton.

Slow the blower down as much as you can; no lower than 325-CFM per ton of cooling.
Remove the fan-off time-delay; after condenser is off it cycles the moisture off the coil into the rooms.

What are the on & off times? Important to know...

What is the indoor temp-drop at 50-% RH; or even if U don't know indoor RH?

On 90°F days it should keep humidity at 50% or lower.
 
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