New American Standard not holding temperature

I just got 2 new HVAC systems installed (upstairs and downstairs), and I noticed during the day, the downstairs unit doesn't want to hold the temperature. The other day, I had it set for 78, and it crept up to 82 (starting around 3PM), and didn't get back below 80 until 10PM.
Now it's hot here in Atlanta for the past few days, but these are new units (2.0 ton downstairs and 2.5 upstairs). The upstairs unit seems to maintain the temperature without a problem.
Today I set both units at 75 (cooler than usual - just a test to see if they hold). The upstairs is still 75, the downstairs is 78.
Also, in the evenings (with the downstairs unit constantly running) I sometimes feel a little warm (not terrible) sitting in the den, but then feel a burst of cool air (like the unit just clicked on).
Any ideas what could be going on? Could the weather (97 outside right now) be the culprit? (Though my upstairs maintains without a problem) Or the thermostat? Or bad unit?
The installer says he is going to try some "expansion valve" at the coils - does this make sense to anyone?
Thanks
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@mail.com wrote:

The downstairs unit id not working properly, which could be for many reasons.
If he is installing TXV metering devices on the E-Coils, that's what they should have to begin with. Do a little reading & thinking, also take some temps indoors & outdoors at the condenser. Also, get a percent humidity gauge.
Here are two of the page links: First the Ductwork Design & functioning - http://www.udarrell.com/proper_cfm_btuh_duct_sizing_air_conditioning_systems.html
After the ductwork & airflow is correct - http://www.udarrell.com/ac-trouble-shooting-superheat-subcooling.html udarrell
--
WISDOM PRINCIPLE DIRECTED EMPOWERMENT COMMUNICATIONS -
THE REAL POLITICAL ISSUES and WISDOM BASED PEOPLE EMPOWERMENT
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
What is a [humidity gauge?]
Could you mean a sling psychrometer?
Zyp
wrote:

http://www.udarrell.com/proper_cfm_btuh_duct_sizing_air_conditioning_systems.html
http://www.udarrell.com/principled_adjudication_disputes_administration_justice.html
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Zephyr wrote:

--
WISDOM PRINCIPLE DIRECTED EMPOWERMENT COMMUNICATIONS -
THE REAL POLITICAL ISSUES and WISDOM BASED PEOPLE EMPOWERMENT
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@mail.com wrote:

If I were you:
1. Get another HVAC company out and have them look over both systems. 2. Have them also provide you a heat load for downstairs system to see if the first HVAC company put in the right size system.
--
Moe Jones
HVAC Service Technician
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

So have the installing company diagnose and correct the issue.

I have lots of ideas, however, the exact problem can't be located right now. Ya see, I sent my crystal ball in for calibration last week. So you might check back in a week or so.

Don't know, what design temperatures are listed in your manual J calcs?

Or an installation issue Or a refrigeration issue Or a ducting issue
How many guesses would you like?

It makes sense that they don't know what the actual problem is... as if they knew, they wouldn't be *trying* anything. They would be correcting the real issue and know what that real issue was by doing a proper diagnosis.
Any chance you went with the lowest bidder?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.