Section R. 325.2434 - Supply ventilation systemsRule 34.
(1) A supply ventilation system shall be provided to ensure a flow of air into the working environment to replace the volume of air exhausted.(2) A mechanical air supply system shall be provided if its absence will result in building negative pressures sufficient to cause back-drafting of vents from fuel-fired equipment or ineffective control.(3) Mechanical air supply volumes shall be heated to maintain a minimum air temperature of 65 degrees Fahrenheit measured at the point of air discharge to the space. Exceptions to this requirement are refrigerated storage rooms, special process rooms, and similar locations where lower air temperatures are essential to the preservation of the product or service, or, if in the opinion of the director, a lower air temperature will not be harmful to the health of the persons affected.Mich. Admin. Code R. 325.2434