Replacing an HVAC system can be costly due to the labor, materials, and specialized equipment required. Professional installation is necessary to ensure the unit meets local code standards and that any existing ductwork is configured correctly for maximum efficiency. Additionally, there are costs associated with purchasing a new HVAC system based on size, features, and efficiency rating. Disposing of the old unit must also be done safely. All these factors contribute to why replacing an HVAC system can be expensive.