Topic
7 guides.
Washable filters save waste but most are MERV 8, which catches large dust and pollen and little smoke-size particulate. For allergies or smoke, a disposable MERV 13 is the better buy.
Air conditioning dries the air as a side effect of cooling. In damp basements and mild, muggy weather it does little; a dehumidifier does the job. In humid summers, many homes need both.
A bypass HEPA unit pulls part of the return air through a HEPA filter with its own fan, so it does not choke your furnace. EPA says most MERV 13 filters get close to HEPA results anyway.
Most purifier HEPA filters last 6 to 12 months; a few last four or five years. The right answer for you depends on run time and how dirty your air is. Here are the makers' own figures.
For most forced-air homes, yes: MERV 13 is EPA's suggested minimum and catches at least half of smoke-size particles. The two caveats are your system's airflow and how often the fan runs.
Efficiency is liters of water per kWh. Our top small-space pick, the avylo ADC018, is certified at 2.05 L/kWh and an estimated 257 kWh a year; here is the ranked list and how to read the label.
If you cannot see light through it, it is gray all over, or the system is struggling, change it. EPA says an overloaded filter will not work well and can send air around the filter.
