Good system design and furnace sizing is vital for any furnace replacement job. Hiring an experienced company that employs skilled technicians adept at properly sizing furnaces and designing optimal HVAC systems can help ensure you get the right heating solution for your Rockville home. Your installation estimator will perform a “load calculation” to properly size your furnace and provide you with workable options. Factors like square footage, number of windows, insulation quality and exterior wall sun exposure all go into this calculation to ensure optimal accuracy.