The Washable Air Filter still has a place in the air filter world. Even as air quality concerns have put the focus on high efficiency air filters and away from the lower efficieny ones. Being one of the largest distributors of air filters in the United States and actively supplying into nearly ever industy we still see a need for a filter that is washable instead of disposable, and have identified 6 times we would recommend them:
- When IAQ isn't the driving force for filtering the air. There are some instances, like unit-vents, where it is either not a main goal or possible to use a high-efficiency air filter and the washable air filter works well. In this application there is enough particle removal to keep the little fan and coil mostly clean, and because washables have sturdy metal frames if there is a big expanse (10"x40"x1" is a common size) having the strong frame ensures the filter does not lose its shape and stays properly installed in the unit.
- Very Large Particles are the main target for capture. Again, the focus here is equipment protection and not IAQ, large particles can casue damage and inefficiencies to equipement and can also just make a mess of a production or warehouse area. In these cases where the level of cleanliness of the space is at a lower thershold and we only really need to capture large particles then disposable filters may not be best.
- Low Airflow Resistance - SOMETIMES Here we get into the weeds a little. Just because a filter doesn't catch much particles doesn't mean it allows air to pass through it easily. Some of the most restrictive filters we supply are MERV-4 metal washables. This is simply a product of the airflow dynamics through the media. There are however newer washable medias available that allow for very low airflow resistance and decent particualte removal.
- Wet Environments. This is the number 1 area that a washable air filter is currently used. Becasue of their rugged, durable, and hydrophobic construction they are a perfect solution to a wet or humid environment as they can act as coalesers and actually reduce the amount of water in the air - allowing other filters downstream to last longer and do a better job of removing particulate without being compromised by wet air which commonly leads to either filter failure/collapse or higher static pressure due to water being trapped in a traditional dispoable filter.
- First Layer of Protection. Along the same line as a wet environment, if you are having problems with the disposable filters needing to be changed too much and you want to add an additional level of pre-filtration then a good quality washable may be a good solution. The only caution here is you don't want to be creating another maintenance issue while trying to solve a different one.
- Homes/Residential. While I understand that people want to use high-efficiency filters in their home, and there is a substantial industry that makes and supplies "HEPA" filters for home use it typically is not practical. Putting aside the argument that those filters are restrictive and burn-up fan motors (which I don't presribe to for a couple reasons, but that's a different post - please email me if you'd like to find out why I've come to this conclusion for now though) there are some nice washable options that will fit well with how residential furnace/air conditioning systems work. Plus you get the green/sustainable benefit of not having to throw away filters every month or two - a well maintained washable air filter in a home system should last 5+ years.
Now, with these scenarios of when it may make sense to use a washable filter, do not misinterpret that washables are good primary filters - for most applications we would still recommend a filter of at least MERV-13 for IAQ reasons. Each application though should be reviewed or audited and these are just a few where we've found the washable filter to be a good fit.