Vents are not necessary in a basement. Places that are underground tend to stay cooler naturally. Only way I would do this is if someone was going to stay down there permanently or I was going to use as an additional room.

I have a 2500 sq ft finished basement that’s mostly below grade but a walk-out. I needed a dedicated HVAC zone if for no other reason than to dehumidify that much space in the summertime.

Thanks for your reply. What about air quality/rotating air for a/c?

Thanks for your reply. I’m looking closer at 700 square foot, but agree humidity is a consideration.

Basements stay cool, so I would only be concerned with a heating source and moisture removal.

We’ve looked into a dehumidifier + vented fireplace or baseboard heat as a good option. We also looked into a mini-split as a more expensive option.

To add to my question…I’m more interested in air quality, circulating air for a/c unit, humidity, etc.

Couldn’t I also simply get dehumidifier and/or air purifier?

Thanks for your reply!

If pulling in outside air is what you’re after and cost isn’t really an issue, then I’d go with the mini split. It’s usually the most convenient solution imo, unless your finished basement is fully below grade, then your mini split will need a pump to dehumidify, which may be noisy.

After talking with a few contractors, we decided against it because of cost. We can always open a window if we need fresh air. An ionizing fan could also be an option.

Edit: also worth noting, our basement temp never rises above 70, so an AC is never really a concern, and our dehumidifier has a built in fan to move air.

Did you test your basement for radon before finishing?

Thanks for your help. Sorry to sound naive, but what’s a mini split?

Could your existing system support that much extra space? I don’t know if a dehumidifier alone would handle it. Maybe a small heat pump would be best without breaking the bank?

They’re also known as ductless heat pumps/air conditioners.

https://cdn.thewirecutter.com/wp-content/uploads/2019/06/mini-split-acs-lowres-1.jpg?auto=webp&quality=60&crop=1.91:1&width=1200

An example of what they look like inside.

If your planning on spending a lot of time down there, I’d suggest putting in the vents if cost effective. A dehumidifier is certainly an option, but it’ll cause noise pollution if your watching tv, hobbies etc…

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Yep, humidity is definitely condensation.

This should not be an issue either. Just like nukethemoon said below you can utilize a dehumidifier with a fan if you are overly worried about air quality/air flow. What are you using the basement for? If just for storage I would not do any of this and save my money.

My kids learned this song in kindergarten, sung to the tune of Darling Clementine, and spent many hours teaching it to me:

Evaporation
Condensation
Precipitation
Collection…
(repeat until Dad screams)

So I am gonna have to disagree with you there lol!

Thankfully we already had a radon mitigation system installed.

Good point. I have seen them, however, that run off a timer. Perhaps I can turn them on overnight?

Finished basement…watching movies, kids playing, etc.

Well in that case it may be worth the split unit nuke brought up, however those can get pricy if you do not know how to install yourself. The unit may be reasonable, but labor is usually expensive. I had one put in a room I built inside a non climate controlled warehouse and it was about 6k. The one I put in was larger than the one nuke shared earlier.

Yeah, don’t want to dissuade you from them. Just purchased one a few months back. home brand. Around $200 Good reviews, settings for auto humidity levels etc. seems to be a good product.

Thanks for the input. Appreciate your time.

Good point. Probably not, therefore perhaps best to not tap into it.

Np. In addition, my basement is 1300sqr ft. I had left the vents closed over the summer to save on ac costs. It got a lil “damp” after awhile. Plugged that thing in and within a week was comfortably dry. Good luck!

Thank you!