How to Determine the Right Furnace Size for A Home
A furnace is valuable and essential residential heating equipment that keeps the interiors warm and comfortable when the weather outside is cold. Homeowners looking for a furnace, whether as a replacement for an old unit or installing in a newly-built home, remain concerned about figuring out the right furnace size that can provide sufficient heating for their homes. HVAC experts lay a lot of emphasis on the importance of choosing the right-sized furnace.
Oversized furnaces are less efficient, contribute to poor indoor air quality, short cycles, make too much noise, have a shorter lifespan, and require frequent repairs. Undersized units provide uneven and insufficient heating, lead to high energy bills, and experience frequent breakdowns.
How to determine furnace size
One way to ensure that the home gets the furnace size suited to the home’s needs is by working with an experienced HVAC contractor. For homeowners willing to do the calculation for the energy requirements of their home to stay warm and then purchase the appropriately-sized furnace, we present here the correct ways to determine the furnace size:
BTU or British Thermal Unit measures the energy required to warm a pound of water by one degree Fahrenheit. Furnaces are sized based on the heat they produce every hour measured in BTU. Therefore, a higher BTU rating signifies more heating.
Calculate the home’s square footage
The first factor to consider is the square footage of the house. The bigger the home is, the higher the BTU requirement to provide adequate heating. Calculate the area of each room and add them up to get the total square footage. Multiply length and width if the room is rectangular. For a triangular room, multiply length and width and divide the result by two. For unusually shaped rooms, divide them into small areas for individual calculations. Avoid measuring areas without ducts. Several furnace charts mention the required BTUs for a particular home size. For example:
A 1,200-square foot home needs BTUs ranging between 35,000 and 75,000
An 1,800-square foot home needs BTUs ranging between 45,000 and 90,000
A 2,100-square foot home needs BTUs ranging between 65,000 and 125,000
However, it might not be accurate, as it represents a broad range rather than a specific unit, and therefore, it is essential to consider other critical factors.
Climate zone
The climate of the region you reside in plays a critical role in determining the BTUs needed for heating the home. Areas in cold climate zones require a more powerful furnace than areas experiencing milder temperatures or fall under hot and dry climate zones. Find out the climate zone for the region and multiply the square footage by the lower range recommended for the particular time zone if the house is adequately insulated or a higher number for old and poorly insulated. For example, a well-insulated home of 1500-square-foot under the climate zone with a heating factor ranging from 40 to 45 BTU will require 60,000 BTUs to keep the house warm and comfortable.
Other essential factors
Quality and number of windows, sun exposure, home’s age, number of residents, ceiling height, house shape, roof color, number of floors, furnace’s energy efficiency rating, presence of ductwork, and ceiling fans also affect the furnace size.
Choosing the right-sized furnace means more efficiency and comfort. Hire an HVAC contractor if all the calculations seem daunting and overwhelming. Working with an experienced professional means making informed purchasing decisions.
Fix My Air DFW of Fort Worth specializes in residential and commercial HVAC services including routine maintenance, installation, and repair. All makes/models. Call us at (817) 439-9811.
