Hello all!

I would like to hear your advice for a nonresidential HVAC project I am working on (climate zone 3C). A 75 sq. ft. ‘office space’ room in a building needs increased cooling capacity (it has to be separate from the central air system), and requires at least 30 CFM of outside air ventilation. The hourly sensible heat gain for the room is about 5,000 Btuh, so Title 24 requirements mean I’m looking at 6,000-7,000 Btuh mini splits.

My original idea was to knock out the fresh air intake on a ceiling cassette and use a 4″ duct directly outside, but I don’t know how I can be sure that fresh air intake hits that 30 CFM requirement (I’m guessing it will only provide 10-20% of the max cfm the mini split provides, which would be right around the 30 mark).

My other option is the Panasonic WhisperComfort ERV, which should be able to supply the 30 CFM supply air but will be a pain to duct in such a small space (very little attic room).

I welcome any advice or considerations I’m missing!