For a 1,000 square foot home, the cost of an HVAC system is $6,000 to $12,000, including a new furnace, air conditioning unit, and ductwork. For larger homes and more complex setups, however, the price could be significantly higher. For central air-conditioning, you'll pay $3,000 to $5,000 and up for a 2,000 square foot home. A new furnace in a central heating system costs $2,500 to $7,500 or more. If you don't need ductwork, the cost of a new heating and cooling system can be significantly decreased.