Due to indoor air safety, health and moisture concerns, building scientists recommend that unvented appliances never be installed within the conditioned space of homes. Additionally, atmospherically vented and/or fan-assisted draft systems should be installed separate from the conditioned space. Unvented systems are identified as having no systems to vent combustion by-products to the exterior. Atmospherically vented and fan-assisted appliances rely on surrounding atmosphere to provide for ventilation of combustion by-products to the exterior. Each type of appliance has the risk of introducing harmful combustion gases, such as carbon monoxide, and moisture vapor back into the space in which they are located - greatly adding to indoor humidity levels and increasing the risk of unsafe indoor environmental conditions for building occupants.
Unvented combustion appliances, fireplaces or space heaters should not be installed within or adjacent to the conditioned space of the home. Atmospherically vented and fan-assisted draft appliances should be installed separate from the conditioned space.
Vent all combustion fireplaces and appliances to remove combustion products as well as process fumes to the exterior of a building.
Atmospherically vented and fan-assisted draft appliances may be installed in unconditioned locations adjacent to conditioned space, however all walls, floors and ceilings separating the appliances from conditioned space shall be air sealed and insulated to meet the IECC 2015.
- The technical advisor will visually confirm compliance during the mid-construction review and final inspection.
- Technical Advisors shall field verify that atmospherically vented and/or fan assisted draft appliances have been separated from conditioned space via a blower door test.
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