What size furnace is needed for a 3000 sq ft house?

The size of the furnace needed for a 3,000 sq ft house typically depends on factors such as climate, insulation, and home layout. A general rule of thumb is to use about 30 to 60 BTUs (British Thermal Units) per square foot, which would mean a furnace with a capacity of approximately 90,000 to 180,000 BTUs. It's best to consult with an HVAC professional who can perform a detailed load calculation tailored to your specific home conditions for the most accurate recommendation.