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Question DetailsAsked on 1/7/2016

We have 2 dogs. So what is the best disposable air filter to put in the Ventilation system?

To reduce indoor dust and pet dander

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2 Answers


A Merv 8 rated 1" pleated filter.Definitely not a 3M brand filter,they are to restrictive for proper air flow,avoid them.


Answered 4 years ago by BayAreaAC


Here is an explanatory article on filter ratings -

BayAreaAC's answer might have been a bit simplistic - you need to get a filter that meets the rating of your furnace. Filter MERV ratings are based on a specific size of particle they stop (effectively about 3mm or larger for MERV 8) and are rated at a specific entrapment efficiency (single-pass of the air) at a certain airflow. Unfortunately, there is not a standard airflow rate (velocity) for the testing, so a lot of filters are rated at a very low airflow, which makes for a low air pressure across the filter hence a higher efficiency than might be the case in real-world situations. Comparing two same-sized filters with the same MERV rating, the one rated at a higher airflow or velocity would be the more effective.

What particle size removal you need depends on the contaminants you need to remove - hairs are large so a low MERV rating will do, household dust around 8 is commonly recommended, cat dander (smaller than dogs generally) and pollen MERV 11 or higher is generally recommended if critical to an occupant, as opposed to just nuisance level removal being needed.

Check manufacturer recommendations (in your manual and online by model number) for several things - dimensions of course so it fits the frame right and does not let air flow around the filter, filter thickness (many units require a specific thickness to fit right in the filter frame), minimum required airflow through the filter (sometimes specified as a certain pressure drop at a certain airflow), and your desired MERV rating.

Also - go with a brandname filter, not a no-name or chinese branded import which may or may not accurately report its efficiency or be well made.

Unfortunately, due to resistance from manufacturers, a rating system for actual airflow capacity of the filter is not standardized or required to be reported on the filters, so you should go with the recommendation of the manufacturer and your HVAC technician as to what type and brands are likely to work well without causing problems. Do NOT go with too restrictive a filter without technician input, as too low an airflow can cause overheating of the furnace and premature fan motor failure.

Almost any commercially available filter will trap dog hair, which is generally over about 100 microns in diameter - dander and dust requires a finer opening size, and MERV 8 is near the higher-end for residential filters. For fine dust or allergen control, MERV 11 pleated filters (which give more surface area for the same frame size, hence less airflow restriction from the smaller opening size) are commonly recommended.

One other thing - personally, I detest "paper" as opposed to woven cloth filters - they tear easily, tend to commonly have manufacturing defects where the paper is glued into the cardboard frame, and the cardboard frames tend to be flimsy and buckle easily. I recommend a high-quality woven synthetic fabric filter with a sturdy border - which is likely to run about $4-10 each in 6-12 packs as opposed to $1-4 each for cheapos or paper or random orientation fiberglass "mat" type filters - the "old" mesh or mohair looking type, which do a lousy job of filtering out the finer materials.

Disposable electrostatic ones do a substantially better job of trapping fine dust and dander, and are commonly recommended for people with allergies or respiratory issues - around $10 each roughly in multi-packs.

Metal and washable disposable ones are generally not recommended - the technology for a reusable filter just has not come to the point of being efficient and economic at the same time.

This AL article shows a typical low-MERV fiberglass or polyester mat filter as the first photo, and a pleated woven one that the guy is handling further down.

Bob Vila also discusses and shows different filter types in the following link -

Bear in mind, the higher the MERV rating, the more of the contaminants in the airflow the filter will catch on each pass - but that also means it is more important to check it for clogging and change it more often so you do not risk damaging the furnace by limiting airflow.

One other thing - a unit that recirculates the return air through the filter will be a much cleaner airflow, and whether or not it brings in dirty or clean outside makeup air into the circulation path can also make a significant difference in how dirty the air in the ducts is. How much outside makeup air the furnace and water heater bring in from outside can also make a difference if brought in through an opening in the wall rather than fully ducted to the unit, as in dirty environments (deserts, farm areas, beaches, pollen-heavy tree and flower field areas especially) that air can bring a lot of contaminants into the house and mix them with household air before being exhausted with the combustion gases. Of course, the further away the makeup air vent is from the appliance, the more opportunity for that to happen.

Answered 4 years ago by LCD

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