Questions about Filters

Frequently Asked Questions About Filters

You’re not alone and there’s nothing to be afraid of. Many homeowners have questions about the filters that go into their furnace or refrigerator. We’re here to some of the most common questions on this page.

If you have a question that’s not covered here, call us at 1-888-407-5688 and one of our filter experts will be happy to give you a thorough answer. You can also reference our handy glossary for specific definitions of filter-related terms.

Furnace Filter Questions

1. What is a furnace filter?

Furnace filters are removable devices designed to trap dust, dirt, allergens and other particles, keeping these airborne contaminants from entering your home through the ventilation ductwork.

2. How do I find my furnace filter?

Furnace filters can be located behind a panel, inside a slot/opening next to ductwork or behind a vent grate. Begin your search in the space where the HVAC unit is located. If you are not sure where the unit is located, switch the heating/cooling fan on and listen. Follow the sound to the unit. Sometimes filters are not within the unit but located in a return air grille/vent in the house. The grill should be hinged and when open will expose the filter.

3. How often should a furnace filter be replaced?

It depends on the filter type. Replace fiberglass, flat panel filters monthly. Pleated or box filters can have longer life spans, usually three months. However, a filter’s lifespan varies depending on its construction and the amount of particulates it has to trap due to environmental conditions. Always refer to the manufacturer’s replacement recommendations.

4. What happens if the filter is not replaced?

A dirty filter can’t remove allergens and particulates properly. A lack of proper filtering can negatively affect a home’s indoor air quality(IAQ.)

5. Does the filter have to be replaced with one made by the original manufacturer?

OEM or original equipment manufacturer products can offer a manufacturer’s guarantee but a quality aftermarket filter will often perform just as well.

6. Where is the filter’s size listed?

The size for most furnace filters can be found printed along the outer frame of the filter. The size will be printed as three numbers configured like this: 16 x 25 x 1.

7. What are the numbers on the furnace filter frame?

The numbers printed along the outer frame of the filter are its dimensions or size. This is the nominal measurement, the number you need to know when ordering the right size for replacement.

8. There isn’t a size on the filter frame. Now what?

If you can’t find any dimensions printed on the frame of the filter, measure the length of each side with a tape measure. Round up to the nearest inch and you should have the filter’s nominal size. Match that size to the list of sizes provided in the pull-down menu on our page “Find Your Filter by Size.”

9. What does MERV mean?

MERV stands for “Minimum Efficiency Reporting Value”. It is a rating number given by an independent testing company (ASHRAE) identifying the product’s filtration capabilities. The larger the MERV rating, the smaller the particles (and the greater the number) the filter can trap.

10. If a filter doesn’t have a MERV rating, will it still trap contaminants?

Yes. Some filter brands do not contain MERV ratings, while others still provide their own ranking system within their product line. Most OEM filters will have a MERV rating.

11. What’s the best MERV rating for someone with allergies?

Filters rated MERV 8 and higher are best for homes with allergies and asthma sufferers.

12. Why do pleated filters have higher MERV ratings?

The folded or pleated construction of pleated filters allows this style to capture more particles than a flat panel style – better ability to trap particles equals higher MERV rating.

13. Are flat panel and fiberglass furnace filters the same?

Fiberglass filters typically are a flat panel-styled filter.

14. Are furnace filters washable?

Some furnace filters are washable. This style will be labeled washable and needs to be cleaned monthly. Fiberglass and pleated filters are disposable.

15. Can I set an automatic reminder with Discount Filters for installing a replacement filter?

Yes. Contact one of our Filter Specialists toll free at (888) 407-5688 or via our Contact Page where you can initiate a live chat.

Fridge Filter Questions

1. What is a refrigerator water filter?

If your refrigerator has a water dispensing system or ice cube maker, it has a filter to remove impurities often found in drinking water.

2. Where is the refrigerator water filter located?

Some water filters can be found in the base grille of the refrigerator or inside the refrigerator near the top, sliding out of a compartment in the ceiling area.

3. When does it need to be changed?

Always refer to the refrigerator’s owner manual regarding how long to use a water filter. However, most filters need to be replaced every six months. If your refrigerator has an indicator light, change the filter when the light turns yellow or red.

4. How do I know which filter to order as a replacement?

The filter part number is listed in the refrigerator owner’s manual. You also can remove the current filter, ordering the same brand and model number.

5. Do I have to order the same filter brand that came with the refrigerator?

Not necessarily. OEM or original equipment manufacturer filters are available for most refrigerator brands and models. Aftermarket filters are available as well. Often, aftermarket brands cost less and offer similar filtration capabilities.

6. What does the water filter really do? Why do I need to change it?

The filter removes harmful contaminants such as chlorine, lead, rust, turbidity, cysts and other pollutants that can make the water taste bad and potentially make you sick. Changing the water filter as recommended keeps the drinking water and ice cubes clean, clear and healthy.

7. If I buy filters in a multipack, will they expire before I use them all?

No. Store your extra water filters in a cool, dry location and they will be fresh and ready when you need to use them.

8. The water does not taste right after installing the new filter. What’s wrong?

It could be air bubbles in the filter. If you did not discard the first gallon or two of water after installing the new filter, the water could taste “off.” Run one or two gallons of water through the system. If the water still tastes odd, check to make sure the filter is installed correctly and then refer to the troubleshooting guide in the refrigerator owner’s manual.

9. How can I be sure the filter is installed correctly?

Gently tug on the filter. If it slides back out, it is not installed properly. All filters have a stopping point. Some just pop in while other require a turn—it may be a half or quarter turn depending on the model. Listen for a slight clicking noise.

10. The refrigerator water is dispensing very slowly. Is this a filter issue?

A water filter that needs to be replaced can cause the water dispenser to run slow or even spurt.

11. What does it mean when a filter specification refers to Standard 42 or 53?

Standards 42 and 53 are certification from the non-profit NSF International. Standard 42 refers to the filter’s ability to reduce chlorine from tap water. Standard 53 refers to the filter’s ability to reduce several more contaminants including lead, benzene, rust, turbidity and cysts that can cause illness.

12. Are all filters tested and certified by NSF International?

No. However, many of our filters at Discount Filters do carry NSF International certifications.

13. Who is NSF International?

They are the National Sanitation Foundation International, a worldwide leader in providing public health solutions.

14. I’ve changed the water filter but now can’t get the indicator light to turn off. Does that mean the filter is not working?

No. Often you need to hold in the reset button for several seconds for it to reset. If you just tapped it, it probably didn’t reset. If you’ve held the reset button in and it still hasn’t reset, refer to the troubleshooting section in the refrigerator owner’s manual.

15. Can I set an automatic reminder with Discount Filters for installing a replacement water filter?

Yes. You can reach one of our Filter Specialists toll free at (888) 407-5688. You can also chat live with a representative on our Contact Page.


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