In general, you should be removing lint from your dryer’s lint trap after each use, as build-up can clog the dryer and be an unfortunate cause of a house fire. Disposing of the lint before and after every use is easy enough to remember, but actually cleaning the filter is a little different. Statewide Appliance Spares recommends giving the mesh filter a deep cleaning every three months with hot water and a little detergent.

Obviously, it’s important to change your air purifier filters. A dirty filter can compromise the efficiency of your air filter, and if you have an older model, they don’t clearly indicate when they need to be replaced. Some filters last longer than others, but air purifier company Brondell recommends changing filters on the following schedule:

True HEPA: 8,760 usable hours or about every 12 months

Activated Carbon: 8,760 usable hours or about every 12 months

Mesh Pre-Filter: Should be cleaned every 2-4 weeks

Your oven range filter has probably never been touched, but years of buildup can be unsafe. Air conditioning and heating experts with Ambient Edge say oven range filters should be changed every one to three months—though your milage may vary wildly depending how often you cook. The oven hood filters out smoke and grease, and regularly changing the filter helps the hood do its job. So, if you’re cooking a lot, keep your oven range filter in mind.

Replacing humidifier filters helps keeps bacteria at bay, but when to change the filters depends on the type of humidifier and the quality of your local water. According to Water Filters Fast, “you will need to change the filter at least once during the winter/heating season when it is being used daily,” and we agree. And locations with particularly hard water should change humidifier filters even more often, about three times a season to function properly.

Out of the many appliances with filters, vacuum filters have the most visible effect when it isn’t changed. When the vacuum filter is no longer functional, the vacuum will leave behind dust no matter how many times you empty the canister or bag. When that happens, it’s a good sign the filter needs to be cleaned or replaced. Check your vacuum filter every six months, at minimum, if you use it fairly regularly. If the filter is soaked and can’t be cleaned, it’s time to buy a new one. Otherwise, you can replace filters once a year to be safe.

Most air conditioners warn us when it’s time to clean out the air filter, but we often ignore the little red light. These filters must be cleaned or changed to keep your AC running though, so plan to clean or change your AC filters every 30 to 60 days. If you have severe allergies, cleaning filters every three weeks can help prevent flare-ups.

When your water filters need changing, they stop doing their job well, and according to Home Warranty, we should replace the filters in our sinks about every two to three months. The filter you probably pay the least attention to is your refrigerator water filter, the one connected to your refrigerator water and ice dispenser. You’ll want to change the refrigerator water filter twice a year (depending on the manufacturer), and if you’re still working with a pitcher water filter, make sure you get new filters every two months or per 40 gallons of use.

HVAC systems don’t need a lot of attention, and changing the filter on a regular basis can keep it that way. Fiberglass filters don’t last very long and should be changed every 30 days. If you have the means and can buy pleated filters, these can last up to six months with average use. Whichever type you choose, schedule regular cleanings and replacements will keep your HVAC running and your utility bill low.

Furnace heaters have filters like any HVAC system and need to be changed to keep the coils working and your air clean. Knowing when to change the filter is based on the type of furnace. You must always check the manufacturer’s guidelines and create a schedule for filter cleanings or replacements. Generally, fiberglass filters should be changed every one to two months, and paper filters every four months to a year.

Similar to an oven range, overhead microwave filters help take care of smoke and grease while you cook. Most microwave hoods use carbon filters that require regular servicing to work. According to Whirlpool, you should change these sorts of filters every six months to function efficiently.