M1505.4.1.5 Furnace Integrated Supply
Systems using space heating and/or cooling air handler fans for outdoor air supply distribution are not permitted.
Exception: Air handler fans shall have multi-speed or variable speed supply airflow control capability with a low speed operation not greater than 25% of the rated supply airflow capacity during ventilation only operation. Outdoor air intake openings must meet the provisions of Sections R303.5 and R303.6 and must include a motorized damper that is activated by the whole-house ventilation system controller. The motorized damper must be controlled to maintain the outdoor airflow intake airflow within 10% of the whole-house mechanical exhaust airflow rate. The flow rate for the outdoor air intake must be tested and verified at the minimum ventilation fan speed and the maximum heating or cooling fan speed. The results of the test shall be submitted and posted in accordance with Section M1505.4.1.7.