Filters
Filters, one of the most expensive category for maintaining your system is your filter. How to choose it. We must look at two factors,restriction of air flow and filter efficiency.

MERV 4 Efficiency <20%
Polen, Dust,
Particle Size >10pm
Minimal filtration

MERV 8 Efficiency 30-35%
Mold, Hair Spray
Cement Dust
Particle Size 3.0-10.0 pm

Legionella, Humidifier dust
Milled Flour, welding fumes
Better filtration

All Bacteria, Tabaco smoke
Superior filtration
Particle Size .30-1.0 pm
Is important to keep it clean, to have less restriction and to protect your blower motor and to keep your indoor air clean. Dirty filters will have more resistence on air flow and the blower motor will overheat. As a result after long period of time, blower motor can broke early.
HEPA Filtration system is high efficiency system up to 99.97%. Is designed for removing particles and bioaerosols down to 0.3 micron. Particle like virus, carbon dust, combustion smoke. HEPA system it is a sealed bypass design which traps particles and prevents them from escaping.