How to Size Your Heating System
Similar to air conditioning, heating systems (furnaces, boilers, and heat pumps) must be sized according to a heating load calculation. While cooling loads focus on removing heat and humidity, heating loads focus on overcoming heat loss through your home's envelope during the winter. Once the size is settled, the HVAC installation cost calculators price the job.
Key Factors for Heating Sizing
- Climate Zone: The severity of your local winters is the biggest factor. A home in Minnesota requires significantly more heating BTUs than an identically sized home in Florida.
- Square Footage: The total volume of air that needs to be heated.
- Insulation and Windows: Well-insulated homes retain heat much better, allowing for a smaller, more efficient furnace.
Furnaces vs. Heat Pumps
Furnaces typically use gas, oil, or electric resistance to generate heat and are rated strictly in BTUs (British Thermal Units) for heating output. The furnace replacement cost calculator gives the installed price for gas or electric.
Heat Pumps, on the other hand, provide both heating and cooling. They are usually sized based on the cooling load (in tons), but in very cold climates, they may need to be slightly oversized or paired with "auxiliary" electric heat strips to handle the winter heating load.
Jump Straight to an Answer
- Furnace size by square footage
- How many square feet each furnace BTU size heats
- Electric furnace size in kW
- Heat pump size by square footage
- The heating and cooling load formula, with a worked example
- Heat pump installation cost by size
- Garage heater size chart
- Window air conditioner with heat vs a window heat pump