In 62.1-2022, where should filtration be installed for adequate PM removal?

• A. Upstream of cooling coils and other wetted surfaces with a minimum of MERV 8.
• B. Downstream of cooling coils and filtered air only in the occupied space.
• C. Filtration is required only for outdoor air, not recirculated air.
• D. Filtration is optional.

Answer: (A)

The main idea is to get particulates out before air passes through critical parts of the system, especially the cooling coils and any wetted surfaces, to protect equipment and improve air quality. Installing filters upstream of the cooling coils and other wetted surfaces ensures that PM is captured before it can foul coils or build up on damp components, which also helps maintain coil efficiency and lower maintenance. The requirement sets a practical minimum filtration effectiveness, using a MERV 8 or higher rating, to remove a meaningful portion of the particles that would otherwise enter the occupied space.

This placement is preferable to filtering after the air has already passed through the coils, which would allow particulates to affect coil performance and could miss PM in recirculated air if filtration were limited to downstream or outdoor-air paths only. Filtration for both outdoor air and recirculated air is needed in 62.1-2022, and filtration is not optional.