Our filter plan is very convenient, it goes hand in hand with the preventive maintenance. We supply a 5 inch merv 11 filter, highest level of filtration available, that last 6 months that provides the best filtration. The filters filter pollen, dirt, dust, even allergens. Dirty filters can also affect the air quality in your home, which is a problem for everyone, especially those with asthma or allergies. Then there’s your carbon footprint—old filters cause your heating and cooling systems to run less efficiently and use more energy. Why it matters: