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  1. #1
    Join Date
    May 2019
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    Exclamation Desperate For Advice - A/C Runs 14+ Hours Day

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    Hey everyone! I want to thank you in advance for your help by sharing your knowledge, wisdom, and advice with me. I also apologize in advance for my ignorance when it comes to HVAC.

    Approximately 18 months ago we had purchased an older home built in 1952 that is 2,869 sq ft heated. We are located in South Georgia. We remodeled the home, and during the remodel we had the old unit replaced with a brand new 5 ton Rheem air handler and outside unit installed by a local HVAC/Rheem dealer.

    When we had the old unit we noticed it would run and never shut off, and the house would never cool down past 76-77 on hot days when the temperature is above 90+. We had the new unit installed and it still runs 12-14 hours a day when the temperature hits 90+ outside. As soon as night time hits, or the temperature falls back down to the 80s the unit is able to cool the house down to 72-73 degrees. On cooler days, especially during the fall, it doesn't run anywhere near the amount it does in the summer.

    I was ignorant and thought maybe our unit was undersized by 1-2 tons especially due to the fact our house still has the original wooden single pane windows, and the house has 34 windows on it. The back of the home faces east, and the front of the home faces west. I did have insulation added to the attic last summer to see it would help. We didn't really see a difference in comfort or run time of unit.

    I had a different contractor come out yesterday to give a quote on possibly adding a mini split to help supplement the main unit. I was thinking this would help solve the problem of run time and overall comfort of the house.

    Long story short, he went to the closet where the air handler is located and said that my problem was not that I needed a mini split to help supplement the main system at this moment, but he said the installation of the new unit was not done correctly.

    He showed me where the air handler is not sealed correctly, and the attic air is pouring into the closet with the air handler. If I understood him correctly, he explained that the air handler is receiving the hot air in addition to what comes through the return thereby making the system have to work harder and never able to cool house down efficiently.

    It seems to make sense to me, but I wanted to see what your opinion was.

    I did reach out to the original contractor who installed the system, and explained my findings and he is coming on Friday to take a look. He said if he finds the installation was done incorrectly he "will make it right."

    Please see attached photos for reference.

    My questions are:

    1) Does this finding seem correct as to why my system runs 12-14 hours on hot days?

    2) If this was not installed correctly, what should I be on the look out for? Any specific things I should look for to make sure it is sealed correctly?

    Again I apologize for the long post, and for my ignorance.

    Thank you again for your help.

  2. #2
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    9,290
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    Keep us posted.
    Regards Teddy Bear
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  3. #3
    Join Date
    Jan 2014
    Location
    New England
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    Run your blower fan only put a accurate thermometer in a return(s) grille and one in your supply, you can move thermometer to different supply and returns. Check temperature difference, if your return duct is not leaking your temperature difference should be the same or very close. Do this when it’s a hot day.

  4. #4
    Join Date
    Mar 2018
    Location
    Chico, Ca #StateofJefferson
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    If enough hot attic air is getting sucked into the unit or return ducting then yes it could be. You could try measuring the air temp right before the airhandler to see how it compares to your supply temps. Did the installer make any changes to the ductwork? Did the house originally have ac or just heat?

    When the installer comes out ask for him to record the static pressure of the return and supply while the ac is running. Also wetbulb/dry bulb of return/supply. Have you ever had a duct leakage test done? Ask him to record all his measurements for your records and let us know

  5. #5
    Join Date
    May 2019
    Posts
    6
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    Thread Starter
    Quote Originally Posted by Bazooka Joey View Post
    Run your blower fan only put a accurate thermometer in a return(s) grille and one in your supply, you can move thermometer to different supply and returns. Check temperature difference, if your return duct is not leaking your temperature difference should be the same or very close. Do this when it’s a hot day.
    Outside Temp 90
    Indoor Humidity 37%

    Return 75.7
    Supply 65.2

    Nest shows current indoor temp of 78. I set it to 75 and it's been going for nearly 2 hours and Nest hasn't moved from 78 indoor temp.

    Thoughts?

  6. #6
    Join Date
    May 2019
    Posts
    6
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    Thread Starter
    Outside Temp 90
    Indoor Humidity 37%

    Return 75.7
    Supply 65.2

    Nest shows current indoor temp of 78. I set it to 75 and it's been going for nearly 2 hours and Nest hasn't moved from 78 indoor temp.

    The house had A/C and heat before. No changes were made to ductwork that I am aware of.

    When we first bought the house, we opened up some walls, and found that 2 of the ducts were disconnected and essentially cooling the attic. Those leaks were addressed, but still didn't make a huge difference in overall comfort of home.

  7. #7
    Join Date
    May 2019
    Posts
    6
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    Thread Starter
    Quote Originally Posted by Makeitcold View Post
    If enough hot attic air is getting sucked into the unit or return ducting then yes it could be. You could try measuring the air temp right before the airhandler to see how it compares to your supply temps. Did the installer make any changes to the ductwork? Did the house originally have ac or just heat?

    When the installer comes out ask for him to record the static pressure of the return and supply while the ac is running. Also wetbulb/dry bulb of return/supply. Have you ever had a duct leakage test done? Ask him to record all his measurements for your records and let us know
    Outside Temp 90
    Indoor Humidity 37%

    Return 75.7
    Supply 65.2

    Nest shows current indoor temp of 78. I set it to 75 and it's been going for nearly 2 hours and Nest hasn't moved from 78 indoor temp.

    The house had A/C and heat before. No changes were made to ductwork that I am aware of.

    When we first bought the house, we opened up some walls, and found that 2 of the ducts were disconnected and essentially cooling the attic. Those leaks were addressed, but still didn't make a huge difference in overall comfort of home.

  8. #8
    Join Date
    Aug 2002
    Location
    Southold, NY
    Posts
    21,571
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    Start by throwing that POS NEST out!

  9. #9
    Join Date
    Oct 2011
    Location
    Gladstone, Oregon (Portland)
    Posts
    1,207
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    But they look cool...lol.

    Nest is such garbage, just spyware is all it is intended for.

  10. #10
    Join Date
    Jan 2014
    Location
    New England
    Posts
    5,237
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    Quote Originally Posted by pastuh View Post
    Outside Temp 90
    Indoor Humidity 37%

    Return 75.7
    Supply 65.2

    Nest shows current indoor temp of 78. I set it to 75 and it's been going for nearly 2 hours and Nest hasn't moved from 78 indoor temp.

    Thoughts?
    I was talking just running the blower fan, no A/C to check temperature difference. Unless the 10 degree is the temperature difference with just the blower fan running?

    If your A/C was running a sweet spot is approx. 20 degree difference between the return and A/C ( give or take )

  11. #11
    Join Date
    Mar 2018
    Location
    Chico, Ca #StateofJefferson
    Posts
    497
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    Any chance you can measure the return air temp right at the air handler? How about a pic of the air handler install?I’d still recommend a duct leakage test done by an independent 3rd party

  12. #12
    Join Date
    May 2019
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    6
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    Thread Starter
    Quote Originally Posted by Makeitcold View Post
    Any chance you can measure the return air temp right at the air handler? How about a pic of the air handler install?I’d still recommend a duct leakage test done by an independent 3rd party
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    The 75.7 was the temperature I was getting underneath the air handler. The temperature right around the air handler in the closet about is 92.3. (Granted this is at 8PM now, and the outside temperature is now 81.) This is due in large part to the air pouring out the attic in to the closet where air handler is. This closet is located in main hallway of house with a louvered door that doesn't appear to be sealed tight.

    Here's one more pic of air handler install further out:

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  13. #13
    Join Date
    Aug 2002
    Location
    Southold, NY
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    If the air is pouring out of the attic there's a good chance a supply duct(s) are leaking.

    Is that the only return?
    What size is that?

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