She is concerned that this 3400 sqft house isn’t going to have enough oxygen to sustain the three of us. Keeping the doors/windows closed with AC on is going to give us recycled air, which is very bad for you. The only time she’ll ever do that is if she feels very hot. Same thing when driving. Even if you turn on AC, she’ll have her window cracked open to let in that sweet hot air to feel that fresh air. Doesn’t matter you press the button to let in outside air. She doesn’t believe in them. She only believes in fresh air straight out the window.
Does she really think the terminus of this state of affairs ends in the suffocation of everyone in the house? If that’s what’s happening, and you don’t live in some sort of special, hermetically-sealed house, then she’s incorrect.
The most likely scenario, from what I know, is that your home’s attic lets in fresh air through the soffits on the eaves of the roof. That air gets pulled into the home (as well as helping prevent mold, etc., in the attic) in order to give you fresh air. Even with all the windows closed, your house is receiving fresh air. I’m no expert, but people have been making homes with HVAC systems in them for a long time. They figured this stuff out. That’s what standards and laws are for.
If your wife just wants the air in the house to be less stale, that’s fine, but surely that could be accomplished by opening a bunch of windows periodically and for a small amount of time. She’s not the only person in the house; the comfort of others is also very important, and 90F is approaching dangerous heat.
She had a lot of serious allergies when she was a child (with medications). They didn’t even give her any painkillers for her c-section because they didn’t know what painkiller they could give her without triggering any allergies. May be that is one reason why she is so paranoid about stuff like this. She doesn’t actually think we’ll suffocate, but she thinks it is unhealthy to breathe recycled air 24x7. There may be truth to it, but like you said, all it takes is opening door/window for a short period of time to get fresh air. She however does the opposite. Keeps windows and doors open for the whole day except for nights and a small amount of time when she turns on the ac. I’ll look into this attic/soffit air, because that sounds like something that might help things. Too bad the hvac guys didn’t say anything about it.