It is very important to NEVER vent air out of the home! The only exceptions are bathroom and kitchen venting as that air is considered undesireable where air that is simply heated by components should be recirculated through the house. HVAC systems are designed to recirculate air and in the summer warm air from the house is simply reprocessed into cooler air. In the winter, that heated air can be utilized as part of the HVAC system as well. When venting out of the home though, that air is replaced by air from either the attic or outside which can be hot, humid, dusty, smelly, etc. It takes more energy for the HVAC to 'condition' that air than air simply heated by components.