Old basement, Stinky HVAC Air: What Can We Do?
June 21, 2020 6:49 PM   Subscribe

We have an old home from 1929. The basement does not smell like fresh spring air, for sure! As a result, when our HVAC runs the AC the air that comes through does not smell awesome. Can we do anything?

We replace the filter every month. Get it serviced regularly. Should we get an air purifier for the basement near the intake? Any ideas would be appreciated.
posted by anya32 to Home & Garden (12 answers total)
 
You might want a professional mold and mildew inspection, unfortunately.
posted by mhoye at 7:01 PM on June 21, 2020 [2 favorites]


Best answer: Do you need the basement air conditioned? Mine sure isn't. If you cover any vents and intakes in the basement, it should not be exchanging basement air with the rest of the house.

If it's extra humid down there, consider running a separate dehumidifier though. Get the kind with a hose that runs into a drain, not the kind where you have to empty a bucket.
posted by fritley at 7:03 PM on June 21, 2020 [2 favorites]


Best answer: Oh, sorry - also, check if you’ve got a backflow valve installed on your basement drain? They don’t just stop the water from backing up, they also stop the bad smells from coming in.
posted by mhoye at 7:04 PM on June 21, 2020 [4 favorites]


Best answer: Yup, our HVAC is right next to a drain where the trap was dry so you got bad smells going through, putting a litre of water in there every 4-5 months is enough to stop sewer gas from coming up.
posted by furtive at 7:21 PM on June 21, 2020 [2 favorites]


Best answer: A dehumidifier would not be a bad way to spend a few bucks. Portable ones; like a Haier, or etc... one that holds a couple of gallons. It fills up; dump it out. Amazon is full of them.

Humidity does nothing good for about anything I'm aware of except for plants, mold, and maybe mushrooms. Which you are probably not considering growing in the basement. .
posted by Afghan Stan at 7:26 PM on June 21, 2020 [1 favorite]


Best answer: I recently got a dehumidifier for the basement and was astonished how fresh it smelled just a couple weeks later. I knew we had occasional dampness problems but dang, apparently the entire Internet was correct in telling me that those were just symptoms of a larger issue. Definitely go for one with the bypass hose for a floor drain, or a pump if you need to move water into a sink or out a window.

Regarding the rest of the house: do you use the furnace filters with carbon in them? They work great for pet odors, at least, and I don't see why they wouldn't help with whatever smells you're experiencing.
posted by teremala at 7:32 PM on June 21, 2020 [1 favorite]


Best answer: Yeah your filters aren't gonna filter that kind of stank (and changing them that often is pointless and wasteful).

You probably need a dehumidifier.
posted by aspersioncast at 8:32 PM on June 21, 2020


Best answer: If you cover any vents and intakes in the basement, it should not be exchanging basement air with the rest of the house.

Be careful with this. A lot of furnaces source a significant portion of their recirc air from the basement and blocking the intakes off can cause the evaporator coils to freeze up.

putting a litre of water in there every 4-5 months is enough to stop sewer gas from coming up.

You can also dump a litre of mineral oil (you can buy it at the pharmacy) into the trap and it won't evaporate.

Besides any floor drains you might have you'll want to make sure the cover on your sump pump if you have one is well sealed. Pumps never completely empty the sump so they'll often have standing water in the bottom.
posted by Mitheral at 11:56 PM on June 21, 2020


Best answer: Two birds, etc: Buy a dehumidifier (every old house basement should have one) and instead of dumping the bucket manually, just let the water drip into the floor drain, which will keep the sump wet.
posted by seanmpuckett at 4:41 AM on June 22, 2020 [1 favorite]


Best answer: Dehumidifier. Professional cleaning of the coils. And we were just told about an ionizing air cleaner called the iWave, which we are considering for our house.

Good luck, I feel ya.
posted by wenestvedt at 5:03 AM on June 22, 2020


Be careful of anything labelled as "ionizing", those devices generate ozone (O3) which you do not want in your house in any concentration.

US EPA Guide

The iWave claims to not generate ozone but doesn't appear to show how that claim is true. Be skeptical.
posted by JoeZydeco at 8:00 AM on June 22, 2020 [1 favorite]


Response by poster: In world record speed it smell better! 2 dehumidifiers and hot water down our open drain. I’ll pour water down the drain regularly just in case. Thank you so much!
posted by anya32 at 5:26 PM on June 23, 2020


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