We are trying to meet the ventilation requirements for mechanically ventilated spaces via ASHRAE 62.1.-2010. It is common for buildings in our region to employ ceiling mounted VRF systems or fan coil units at perimeter zones, however, it is highly uncommon to install filters on VRF interior units or small size AC units, so a majority of manufacturers do not provide interior equipment that allows the installation of filters equivalent to MERV 6.
It is unrealistic to require MERV 6 filters for all small air flow systems due to maintenance issues for these smaller systems. Is there an alternate path available for projects with smaller ventilation systems to comply with the particulate matter filtration requirements for this prerequisite?
Yes, for the EQ prerequisite Minimum indoor air quality performance, small indoor fan coils such as VRF fan coils can be exempted from the ASHRAE 62.1-2010 Section 5.8 or ASHRAE 62.1-2007 Section 5.9 particulate matter removal requirements subject to the following constraints:
1. The fan coil may not introduce outside air directly from the outdoors. The fan coil must either be a 100% recirculating system, or have outside air delivered from a Dedicated Outside air system that filters the outside air.
2. The fan coil cooling capacity must not exceed 30,000 Btuh (9 kW)