Woot is running a big sale on heaters, humidifiers, purifiers, and air conditioning units today, with discounts as high as 68%. Some standout deals include the Emerson SmartVoice tower heater at $100, and the Frigidaire PureA300 HEPA air purifier at $70, down from $159. Refurbished LG window and wall air conditioners are also included at a big discount. Prime members get free shipping on all orders, and the sale ends November 15.  Shop Now at Woot! An Amazon Company

AlorAir dehumidifiers and air quality gear are up to 30% off at Amazon, with the deepest cut on a crawl space ventilation fan. ALORAIR focuses on dehumidifiers for crawl spaces, basements, and water damage restoration, and many of its models have a built-in pump that moves water up and out without a floor drain. Shipping is free for Prime members. Shop Now at Amazon

Choose "Claim free item" on the Amazon product page and this AlorAir Sentinel HD55S crawlspace dehumidifier comes with a free 4-pack of filters, a $65 value. The dehumidifier is already 25% off at $486. That price is below its 90-day average of $519.  Shipping is free. Buy Now at Amazon

Handy for anyone wanting to add scent and a bit of ambient light to a bedroom or office without a lot of fuss, and it's currently $16 (40%) off the $40 list price. Apply coupon code "D5WEJRMC" for a savings of $16. Prime members get free shipping. Buy Now at Amazon

Home Depot is offering discounts of up to 50% off a wide range of dehumidifiers, from small countertop units to large commercial-grade machines. The Edendirect 50-pint dehumidifier, for example, is $170, down from $339.99. Shoppers looking for bigger spaces will also find options like the KESNOS 155-pint commercial dehumidifier at $559.99, marked down from $949.99. Shop Now at Home Depot

This ToLife dehumidifier is $20 off its regular price at Amazon. You'd pay $10 more elsewhere. It covers up to 1000 sq. ft. and includes a sleep mode that runs under 30 dB for quiet overnight use. Buy Now at Amazon

Apply promo code "PRELUV" to get this price, which is a total of $130 off. It covers up to 1,000 square feet and removes up to 70 pints of moisture daily, with a gravity drain system for continuous use without emptying a tank. It also comes with a 5-year limited warranty.

The same code takes 5% off everything else sitewide, as well. Buy Now at Argendon

Basement or job-site flooding situations call for this kind of capacity, since 240 pints a day covers large or damp commercial spaces that standard home dehumidifiers can't handle. At $459.99, that's $140 off the $599.99 list price. Buy Now at Amazon

Update: The price has dropped to $129.93 since this was originally published.

Dealing with damp basement air across a decently sized space, this one's rated for up to 2,000 square feet, which covers most finished basements without needing a second unit. It's priced at $130, a full $470 off the $600 list price. Buy Now at Walmart

Update: The price has changed to $22.99 since this was originally published.

A 4-liter tank means fewer refills, which matters most in dry winter months or for larger bedrooms where small humidifiers struggle to keep up. Walmart has it for $20.99, which is $16 off the $36.99 list price. Buy Now at Walmart

Update: The price has dropped to $39.96 since this was originally published.

A 4-liter tank means fewer refills for larger bedrooms or shared spaces that need steady humidity overnight, and the current $39.97 price is $50 off the $89.99 list. Buy Now at Walmart

Update: The price has dropped to $37.80 since this was originally published.

Good fit for basement or laundry room spaces prone to damp air, since it's rated to cover 500 square feet and holds 50 ounces before needing to be emptied. It's $8 off the $46 list price at Walmart, bringing it to $38. Buy Now at Walmart

Update: The price has changed to $69.99 since this was originally published.

Handy for basements or damp rooms where you want to cut moisture without emptying the tank constantly, thanks to the 85-oz. capacity. At $69.69, that's $49.30 off the $118.99 list price. Buy Now at Walmart

Update: The price has dropped to $208.27 since this was originally published.

Basement and crawlspace owners dealing with persistent dampness will get the most use out of this one, since 50 pints a day covers larger spaces without constant tank emptying. Walmart has it at $209.27, which is $121 off the $330 list price. Buy Now at Walmart

This small dehumidifier works well for damp closets, bathrooms, or RVs where a full-size unit would be overkill, and at $35.12, it's about $15 off the $50 list price. Buy Now at Amazon

Keeping the air comfortable in a large bedroom or living room is the main job here, and the 17L tank means you're not refilling it every few hours like with smaller units. It's $36 off the list price at Amazon, bringing it to $144. Buy Now at Amazon

Update: The price has changed to $50.45 since this was originally published.

Rust and mildew form fast in closets, gun safes, and cabinets with little airflow, and this rod runs continuously to keep that moisture in check without any upkeep on your part. At $50.95, it's about $3 off the $53.97 list price. Buy Now at Amazon

Basement and bathroom moisture problems call for this kind of capacity, since 34 pints a day covers larger or damp-prone spaces without constant tank-emptying. It's $25.56 off the list price, bringing it to $129.99. Buy Now at Amazon

These crystals are made for absorbing moisture in closets, boats, or RVs where mildew and musty smells tend to build up, so they're a practical refill to keep on hand if you already run a moisture trap. At $4.99, that's $0.90 off the $5.89 list price. Buy Now at Amazon

Basements and damp laundry rooms are where an 80-pint capacity actually gets used, pulling more moisture per day than smaller units without constant tank-emptying. It's priced at $112.01, about $20 off the $131.78 list. Buy Now at Amazon