Airmega 200

They don't really work if you have an active infestation. Ive got 4 lg ones in an 800sq ft house and I swear they do almost nothing. We even have this electrostatic filter in the hvac and still I've get systems when the doors close or the AC goes on. I have 2x airmega 200s, germ guardian rated for 900 sq ft, coway with uv rated for 600 sq ft. 2 upstairs and one down. If I were you id try to build the biggest Rosenthal filter or several as they don't get down hall ways or around stairs, etc. The think I don't like is they really tank your electric bill and are very noisy, as they have to stay on high mode.

The NYT just did a review and ranked the Coway Airmega 200 as the best air purifier. They're under $200. I bought two and like them a lot so far. They have an ionizer, but you can turn it off. They're quiet and move a good amount of air. There are two types -- one has a large circular front and sucks in air around the edges of the circle, and the other is a regular rectangular front that sucks air in across the entire front. I have the rectangular front model. They also have a good handle for moving it around. I really liked the Honeywell HPA300 (I think that was the model), but they stopped making them. The ones they sell now look similar but are about 1/3 bigger, and don't perform any better. I feel like the bigger model is really weak at lower levels and only works well on turbo, which is really loud, while the older models worked better at lower levels. And it's just way too big for the average room and has no handles for moving it around. I have one of those cylindrical Levoit purifiers, and it works fine but I don't like how it only sucks in air at the bottom 1/3 of the purifier. A lot of the bird dust I get (I have a grey) is floating much higher in the room.

If each room is 300-400 square feet, the Airmega 150 is way underpowered to get the suggested 4-6 air changes per hour. At minimum, you’d need something like the Airmega 200, but preferably something with a higher CADR so you didn’t have to run it on high 24/7. CADR is always measured at top speed, so it’s advisable to buy a more powerful unit so you can run it on a lower setting and get adequate cleaning without the noise of the top speed. Air purifiers are great, but they are not going to do anything for dust. Please read the stickied thread for more info. As others have mentioned, co2 can make basements feel very stagnant. Getting an ERV/HRV installed can bring fresh air into the space. You should also have the basement tested for radon if it’s present in your region.

I have coway flat version and the round Aim version, one for each bedroom. ayou can go ahead with either of them but the flat version is much quieter than the round one and also from my experience cleans up a few minutes faster than the round one. that said both get the job done well and ai have had no issues. I prefer the flat one since it has the removable pre filter to wash and quieter and firs snugly against wall.

Don't waste the money on Dyson (they're heinously overpriced). Go with one of the Coway models, you'll get more airflow for your money and the filters last much longer than they're rated for. The Coway AirMega AP-1512HH and AirMega 200M are good picks (have both and like them quite a bit). The Levoit and BlueAir models are good too, but they tend to go through filters quickly and that becomes expensive fast. The prefilters on the Coway models are good at catching particles and dust before they make it to the HEPA filter and clog it, so the HEPA lasts much longer. Also, the activated carbon will absorb smells and chemicals. Also, unless you have a giant wide-open space or really big rooms, it tends to work better getting several mid-sized air purifiers vs. one extra-powerful one. More purifiers means more airflow without a lot of noise. They also do a better job covering multiple rooms, since they're less at the mercy of airflow between rooms.

Happy to help! For what it's worth, the Whirlpool suggestion seems to be a similar design to the Coway (with similar benefits). I just don't have previous experience with it, and the Coways are somewhat cheaper and come up consistently on lists of top air purifier models. Note that for many air purifiers, after 3-5 years you'll spend more on HEPA filters than you do on the purifier itself. That's why it's so valuable to have a design that reduces how often the filters need to be replaced. [Wirecutter by the way was my source on being able to run the filters much longer than they're rated for, and they did a good overall set of reviews](https://www.nytimes.com/wirecutter/reviews/best-air-purifier/)