What the work is
A denser filter in a housing built for a thinner one restricts airflow, and restricted airflow is the cause of a long list of expensive symptoms: a furnace tripping its limit, a coil freezing, a compressor working against itself. The filter that promises the most is not automatically the right one.
The fix is filter area, not filter density. A deeper media cabinet gives you better filtration and less restriction at the same time, and it is the change worth making if anyone in the house has a reason to care about what is in the air.
The number to know is total external static pressure, measured across the system. Most residential equipment is rated to about half an inch of water column and a great deal of it in the field is running well above that, mostly because of filters and undersized returns. Above the rating the blower moves less air, the coil runs colder, and the equipment works harder for less.
So we measure before and after. If a filter you want cannot be carried by the system as it stands, the answer is usually more filter area rather than a thinner filter — a deeper cabinet, or a second return — and we will quote that rather than tell you to buy something worse.
What is included
- The static pressure measured before and after, so the effect is a number rather than an opinion
- A filter housing sized to the system's airflow
- What to buy next time, written down, so nobody has to guess in an aisle
- Total external static pressure measured across the system, before and after
What is not
- A filter rating the equipment cannot carry
- Claims about health outcomes. We move air; we are not going to tell you what it will do for anyone's asthma
What to ask anyone quoting this, us included
- What is the static pressure now, and what should it be?
- Will this filter restrict my airflow?
- What size and rating do I buy next time?
- What is my static pressure, and what is the equipment rated for?
- Is the fix a different filter or more return?