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Nest and A/C issues


Premium Member
Sep 12, 2009
Model Number
1-5 years
Hello guys. Question with a bit of explanation. First i know my unit is oversized, has been for the last 3 years. Used to have a lux 1500 stat and just this year slapped in a nest as i heard it would save power, air wave, etc... Sounded good, yet It doesn't appear to be happening that way. Now i did have my AC guy out before cooling season began and he said that they never upgraded my return or ducts to represent the size of that unit, which is a Payne 4 ton. Doing this he said would cause way to much stress on the unit and by making the return and ducts larger capacity would eliminate that strain. So we did that. Now the unit cools fast, way to fast. Cycle times to cool approx 10-13 minutes at nest set at 78, off time approx 15-20. It was 86 outside for these particular numbers.

I have allot more as i have been watching like a hawk, but the numbers are similar in nature. Now nest has a setup called airwave. In case you dotn know its simply means it shuts the compressor off and runs fan utilizing cool coil until it reaches set point. In this case its 77. Nest goes with 1 degree band. So on at 79 as stat set at 78. Turing airwave on seems great and my initial idea to save energy, but based on the system now working better all airwave does is cut my run time down about 3-5 minutes...So a cycle of compressor on would be instead of 10-13 minutes, it would run 6-8 minutes.

Needless to say my KwH is through the roof compared to last year.. First couple months in im about 50 bucks more than last year with similair temps an usage. Note my Bills the last 3 years already have been crazy hence all these things to try to help. The bills are killing me. My neighbor for instance keeps his stat at 74, god i would love that..yet if i did that i would be in deep deep trouble... His bill, same house as mine, give or take a few differences in appliances etc and a York unit is half the bill mine is and his unit is the same tonage as mine 4 ton. Our homes are 1,236 sq. Sorry for the long winded post here. So I was thinking about putting my Lux back on, after all my bills were a bit cheaper then. So here is my main question. Should i do that to test if I can get the compressor to run longer?... the lux had a swing differential of 1-4 which mine was at 4. Or by getting the system to run better by increasing the air its supposed to get only screw me over. Only trying to do the right thing and it may have made things worse.

or i was thinking of getting another stat that would allow cph... although im reading 2-3 per hour is norm and that's what mine is doing even though short run times, its made up in my off times to appear ok although it appears its not. Good thing i dont live in a humid area, i am in Phoenix AZ. My ac did come out and turned the variable fan to its lowest setting which hasnt really changed times at all.

In conclusion, im hurting here $$ wise. I know a lower sized unit would be key here, yet $$ is an issue on that front. When I got this Payne approx 3 years ago, that was about it for awhile on the big expenses. I curse the installer for the issues i had and he caused (ceiling fell in due to improper pan which took drywall out, crack in ceiling, plus more, it was a mess) yet I guess in the end the blame is on me as I didn't research more on what should have been done, J loads..etc..... By the way, unit was checked when ductwork done and everything is working to specs. Even had a blower door test, where I found out my house has no leaks and is very tight.

Any suggestions on what i can do would be very much appreciated. Again sorry for the long post, wanted to explain the best i could. Thank you so much for your time.
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