Fuel burning space heating and/or water heating equipment with a combined input rating greater than 150,000 Btu/hour shall be provided with air from outdoors for combustion and dilution using the methods described in Section 18-28-703.3.
Exception: Single-family and two-family dwellings (including townhouses) are not required to use outdoor air for combusting and dilution. Such dwellings shall be provided with air for combustion and dilution in accordance with Sections 18-28-702, 18-28-703.2, or 18-28-703.3.
Fuel-burnings heating equipment and/or water heating equipment with a combined input rating less than or equal to 150,000 Btu/hr is not required to be provided with air from outdoors. However, the air volume within the space shall comply with the unconfined space definition for the aggregate input rating of all fuel-burning heating equipment and/or water heating equipment installed in that space. Fuel burning appliances typically used on an intermittent basis, such as clothes dryers, residential cooking equipment, and/or fireplaces are not required to be provided with air from outdoors. However, the combined air volume within the adjacent, communicating living spaces (not including bedrooms, bathrooms, and toilet rooms) shall comply with the unconfined space definition for the aggregate input rating of all fuel burning appliances installed in those living spaces.