House in the woodlands, 03 build.

Gets up to 63 in the late morning (temp switch from 70 overnight to 74-75 for daytime, basically A/C doesn't run), come mid-afternoon until the evening (highest heat load) it gets down to 56 or so.

Old house was low 50s and felt comfortable. Feels sticky in the new house.

What steps should I take to figure this out? Had the whole A/C inspected, they are properly charged and are not short-cycling, seem adequately sized. Turned off the ecobee setting where the fan blows without the A/C running to extract the last of the cool air. Measured humidity using both the ecobee and a hygrometer.

needs to have the a/c run more often. probably an oversized unit for the house. or add dehumidifiers in teh house.

it's 3300 sq ft, running 5 tons total (3 down 2 up), a manual J would be needed but at face value and living in it, doesn't seem undersized. i'll keep taking a look

3300sf/5ton=660sf/ton
Prior to ManJ the rule of thumb is
475sf/ton unless an insulated floor above then 575sf/ton in the rockwool days of vented attics

So we might take any focus off of oversized
Let's insure no condensate holding in the pan, draining well, dosed with slimeout tabs all summer
Let's inspect for duct leaks, poor taped joints, etc. as we insulate over ducts
Let's shade the compressor outside
THEN a dehumifier seems justified

2003-2026=23yo
A time to ponder replacement with variable speeds = humidity killers saving dollars
Zoned segregeted systems ala Unit A down unit B upstairs
ManJ that is comprehensive to include shade trees, sunny/shaded windows, et al.

BTW - am not an HVAC guy

A/Cs are 3 year old single speed leaky Lennox's…. Stuck with em!

Gives me an excuse to install an aprilaire when it cools off

How's your attic ventilation? If you were to blow a little smoke up there does it hang, or does it scoot out?

I bought a thermal camera and a fog machine to check it all out

Good idea, didn't know it was an option. Will check it out

Dill-Ag13 said:

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House in the woodlands, 03 build.

Gets up to 63 in the late morning (temp switch from 70 overnight to 74-75 for daytime, basically A/C doesn't run), come mid-afternoon until the evening (highest heat load) it gets down to 56 or so.

Old house was low 50s and felt comfortable. Feels sticky in the new house.

What steps should I take to figure this out? Had the whole A/C inspected, they are properly charged and are not short-cycling, seem adequately sized. Turned off the ecobee setting where the fan blows without the A/C running to extract the last of the cool air. Measured humidity using both the ecobee and a hygrometer.

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The biggest head scratcher here is that you say the data is the same but it feels very different. Not much anyone can offer if you truly had 50% relative humidity air at 70 degrees in both houses and they felt very different. At that rate the only difference is air velocity (fans) and solar energy from windows.

I would personally run the AC at 69 at night and only let it get up to 72 in the day. See how that feels. 74-75 being comfortable in a houston home means you were really dry in your old home.

Beyond that, its time to go air sealing. Outlets, recessed lighting, etc. Anything that punctures your drywall needs to be sealed. Go look for drafty windows, bad weatherstripping, etc.

Once you've air sealed, how is your bathroom fans doing when you shower or after? Those add significant moisture loads to your house. Are you using the fan enough?

Sealing may help, but I had all new windows installed and new attic insulation. When they did the insulation, they sealed all the ceiling gaps around fixtures with expanding. Neither seemed to make a difference in humidity.

Another thing to consider, not all thermostats are equal. One may read 72, but another may read 75. Just because you set it at 72 in your previous house, it doesn't mean the new thermostat's 72 is really the same temperature.

Thanks, all. Have verified the humidity and temps across both floors with a secondary thermometer/hygrometer combo. Running 58-62%. Old house was 50-55 - super comfortable. Bought a small fog machine and thermal camera. Will mess with those and blower speed