Thanks Section327 - I passed that information along.

We had a similar problem in our house we completed last year. The house is 3200 square feet, foam sprayed, with a large living room with full height ceilings. We have a 3 ton on each side. We were having condensation issues in the attics, and humidity issues in the house. I had the return ducts on both sides disconnected, and ran an open return in the attics. It helped tremendously with the condensation issues in the attic, and some with the humidity issues in the house. I run a pair of dehumidifiers off amazon during the colder months to stop window condensation, otherwise its worked great. I saw little change in my electric bill when I began conditioning the attics.

I don't think a 5 ton unit on your size house seems off at all. Even with the spray foam. Keep in mind that the poster above is correct about the "in between" months. That is, October-November and March-April. Things get bad when its 60-70 degrees outside and you get high humidity outside or a few rainy days. Your going to have some 60-70% indoor humidity days. The AC isn't running enough to dehumidify the moisture getting in. I have had this problem in every house I have ever owned. You have a couple of options:

1.) Install a whole house dehumidifier to take are of those "in between" months. That would be an extreme option.
2.) Set the temp a little lower during these months so it runs a little more to reduce moisture levels.
3.) Run bathroom fans when showering and run the vent-a-hood when boiling pots and cooking. That helps alot. I know you said nobody is in the house, but for when you do move in.

I would not make any judgments on the A/C until you get into the summer and see what the duty cycles look like with a higher heat load on it.

Bonfire97 said:

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I don't think a 5 ton unit on your size house seems off at all. Even with the spray foam. Keep in mind that the poster above is correct about the "in between" months. That is, October-November and March-April. Things get bad when its 60-70 degrees outside and you get high humidity outside or a few rainy days. Your going to have some 60-70% indoor humidity days. The AC isn't running enough to dehumidify the moisture getting in. I have had this problem in every house I have ever owned. You have a couple of options:

1.) Install a whole house dehumidifier to take are of those "in between" months. That would be an extreme option.
2.) Set the temp a little lower during these months so it runs a little more to reduce moisture levels.
3.) Run bathroom fans when showering and run the vent-a-hood when boiling pots and cooking. That helps alot. I know you said nobody is in the house, but for when you do move in.

I would not make any judgments on the A/C until you get into the summer and see what the duty cycles look like with a higher heat load on it.

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As a contractor who deals with some seedy contractors, do not do this. If you let them off the hook until after you're moved in (ie you've paid them in full) you'll never hear from them again. You need to get this resolved before you close/final pay/move in.

They made some tweaks to settings and it now goes from mid to high 50s to low 60 % humidity at night now, which is an improvement. We're going to try the American Standard thermostat referenced above and see if that helps a little too. Thanks for everyone's input. Again, happy to share the j load calcs via email or if I can figure out how to post them (or a link to).

Are they PDFs? I could screenshot each page and black out identifying stuff like names and addresses, the post to IMGUR. Images are the only thing that can be shared on texags.

You can also put a Dropbox link to the pdf

Any update? It got stupid hot yesterday for this time of year. Good time to see if your unit is sized correctly.

We changed out the Nest thermostats for the American Standard 824 thermostats referenced above (thanks for that!) and HVAC contractor also supposedly made some tweaks to settings. Humidity levels have been under 60 ever since...between 56 - 59 or so. I'm okay with that I think...although its frustrating that my current 100 year old home stays in the 45ish range, which is much nicer. Of course, I'm guessing the new house will use much less energy even though its 40% larger.

May still consider a dehumidifier down the road...but i wanted to be in acceptable humidity range as is first before we went that route.