The answer to 'cost of system upgrade' is that the cost can vary widely depending on several factors. The total cost for an HVAC system upgrade typically ranges from $3,000 to $15,000 or more, but the exact price will depend on the size of your home, the efficiency and capacity of the new system, the complexity of the installation, and your local market conditions.
Some key factors that influence the cost include the type of HVAC system (e.g. central air conditioner, heat pump, furnace), the brand and model, the required ductwork modifications, and any necessary electrical or structural work. You'll also need to factor in the labor costs for the installation. Getting multiple quotes from licensed HVAC contractors in your local area is essential to getting an accurate estimate for your specific home and needs.