Welcome, 'chucker. Yup, that sounds about right....one low and one higher up. Really any size tyou feel comfortable with, even ones you can close. (like house wall registers) Always have some vents in a shack, no matter what. You need some fresh air to circulate. Many, many threads on this. And DON'T rely on that low oxy sensor to keep you safe; CO levels can still be high enough to get you sick with those. I've experienced it myself. So many think that you're safe from CO with that, it's NOT true. 28 yrs in law enforcement and as an EMT I've seen the guys that trusted those as we loaded their bodies up. I'll never stop preaching this, if I can save but one life.
