My training says that a recirculating exhaust fan can only be installed above an electric range, but that the exhaust fan over a gas range must be vented to the exterior. FWIW, the exhaust fan is part of an over the range microwave, in new construction. Can anyone post a code reference (IRC or Cabo if applicable. Any other codes will do) that makes this requirement, or am I off my rocker? (That may be a whole different thread) I know the manufacturer specs may require this as well. If possible, please cut and paste the applicable code so that I can reference it to a builder, as I do not have access to my code books at the time being. Any help would be appreciated, David Fogle HomeScope Augusta, Ga.