New house...upstairs AC issues...

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New house...upstairs AC issues...

Postby stangman39 » Sun Jul 24, 2011 10:08 pm

Hi all,
I'm new here!

Recently purchased a new house which has 3 levels (basement, main and upper) and each level has their own unit.
I know most areas have been having very very hot temps recently. However, during the day it is pretty much impossible to get my upper level cooler than 80 degrees without running the AC for hours!
I have a home warranty on the house and had an AC tech come out and check the system about 2 weeks ago. He said everything was working fine and the air coming out of the vents for the upper level was 57 degrees.
Well, I've done some testing and checking over the last week.
The attic (where the upper HVAC is located) was getting up to 130 degrees during most days. I used a digital wireless thermometer to test this. The roof is new and I'm pretty sure there is a ridge vent. I recently had a attic vent fan installed (not a whole house attic fan) to remove heat from the attic. I've noticed with this fan it keeps the attic around 12-15 degrees cooler during the hot times. I also noticed in the morning the temp in the attic gets down to 75-80 degrees.

In the morning I can get the upper level down to 78 degrees pretty quick because the attic is cooler. I've noticed in the morning during this time the air coming out of the vents is 65 degrees. During the hottest times of the day the air coming out of the vents doesn't go below 75. So I've got 75 degrees air trying to cool a 84 degrees upper level.
Seems like my issue is the attic getting too hot during the hottest times of the day and the cooler air coming from the AC is not cold enough to cool the upper level fast enough. I'm not sure how else to get the attic cooler so the air is cooler. I have been keeping the t stat set at 84 upstairs just so the AC isn't running all day thus making my electric bill very high!
(I tested the air coming out of the vents on the main level (which I don't have any issues keeping at 78-80 degrees and it doesn't run all the time) and it is a nice 63 degrees).

Thanks for any help or ideas.
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- New house...upstairs AC issues...

Postby heatseeker » Mon Jul 25, 2011 12:24 pm

Sounds like you need some insulation in your attic or maybe better sealed plenums and ductwork. maybe your unit is undersized, or there are some problems with the other units. 57deg and 80 deg temp is 23 deg split. sounds preetty good. also remember home warranty companys aren't going to cover any changes in the current designs. Heat rises too on a hot day you will have problems with the upper floor.
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- New house...upstairs AC issues...

Postby stangman39 » Mon Jul 25, 2011 12:42 pm

The 57 degrees read by the tech was when the attic temp was the coolest and outside temp was around 85 degrees.
I run into issues when the attic temp gets too hot...this making the air coming out of the vents from the AC much warmer than it should be.
I have insulation in the attic but I guess I could look into having more blown in.
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- New house...upstairs AC issues...

Postby heatseeker » Mon Jul 25, 2011 3:19 pm

Sounds like you need a better service tech or you need to upgrade your system. I wouldn't expect much from the warranty company though.
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- New house...upstairs AC issues...

Postby nomadpeo » Thu Jul 28, 2011 7:17 am

check for return air leaks in the attic. test the temperature difference between the return air grill and the entering side of the evaporator. if you have electric heat, you will need to take the second reading at the entering side of the unit. if it's ductboard, poke a hole; if it's metal duct, drill a hole in the duct there. if you have a gas fired furnace, measure the intake of the evaporator by making a hole in the transition just prior to the coil entering side. if the ducts on the return side of the coil are not well sealed, the intake of attic air has a direct effect on efficiency, of course.

you may want to pay for a second opinion on the functionality of your system. even if you have a hot attic and inadequate insulation, it may run a lot, but you should get some performance out of it. the system needs to be tested thoroughly. home warranty companies do not always have your best interest in mind. that is just a personal opinion.

by the way, the ridge vent is effective, but only if there is adequate intake. make sure the soffet vents at the eaves are not restricted with blown in insulation. the natural draft to draw out hot air depends on a source for outside air at the bottom.
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- New house...upstairs AC issues...

Postby heatseeker » Thu Jul 28, 2011 8:48 am

noamadpeo isn't that what i said
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Postby aircooledtx » Thu Jul 28, 2011 4:01 pm

heatseeker -
> Sounds like you need a better service tech or you need to upgrade your
> system. I wouldn't expect much from the warranty company though.


Hey, what the ______hell. What's wrong with technicians who work with warranty company's.
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