When it’s cold outside (even in LA), you need the right furnace to heat your home evenly and efficiently. The size of a furnace directly affects how well it can heat the intended space. A furnace that’s too big will switch on and off frequently; too small and it will run constantly. Neither is ideal.
Additionally, a small furnace will lead to high energy bills, uneven heating, and a shorter lifespan. In all likelihood, you’ll probably still be cold. A furnace that’s too big, on the other hand, might make parts of your home uncomfortably hot while leaving other areas improperly heated. This constant cycling in short bursts could wear it out quickly. To avoid these problems, learn how to choose the right furnace size for your home.
How to Choose a Furnace: 5 Steps
Learning what size furnace you need requires a small lesson on the science of heating. Gas furnaces are differentiated by their BTU capabilities. BTU stands for British Thermal Units. One BTU represents the amount of energy required to heat one pound of water by one degree Fahrenheit. To determine the proper furnace BTU you’ll need for your home’s heating, you’ll have to do a little math.
1. Determine the Square Footage of Your Home
You should be able to find this number on the paperwork you received when you purchased your home. If you can’t find that, you can calculate the square footage yourself.
Start by measuring the length and width of each room in your home. Multiply the length and width of each room together to get the square footage of that room. Then simply add together the square footage of all your rooms.
Don’t include rooms that don’t have ductwork or rooms you don’t plan on heating, such as garages or sunrooms. Most furnace size calculators operate under the assumption that your ceilings are eight feet high. If your ceilings are higher or lower, make changes to your calculation accordingly.
2. Identify Which Climate Zone You Live In
The United States is divided into different climate zones. Your zone will dictate how many BTU per square foot you need to heat your home. A house in Minnesota takes more BTUs than one in Florida. Living in California, your furnace won’t have to be heavy duty.
If you’re working with Mike Diamond, then your home lies in Zone 2 – a hot-dry or mixed-dry climate zone. In Zone 2, you need 35-40 BTUs for each square foot of your home.
3. Calculate the Furnace Size You’ll Need
To determine the number of BTUs you need to heat your home: multiply your square footage by the zone heating factor. If your home is well insulated, use the lower number. If your home is not well insulated or has other factors that may make it harder to heat, use the higher number.
For example: in a well-insulated L.A. home that is 2,000 square feet our equation is:
2,000(sq ft) X 35 (zone factor) = 70,000 BTUs
For this home, we need to install a furnace with a rating of 70,000 BTUs. But we have one more step to finding our perfect furnace.
4. Calculate Your New Furnace’s Actual Output
Before you buy, make sure you’re getting a furnace that’s big enough. When you shop for your new furnace, you’ll notice two numbers on it. The first is the amount of heat it will produce in BTUs. The second number is its efficiency rating. To calculate the actual BTU output of any furnace, multiply the two numbers. For example, a furnace capable of 100,000 BTUs at an efficiency rating of 80% will actually produce 80,000 BTUs of heat:
100,000 X 80% = 80,000
Make sure you calculate this properly before installing a furnace that is too small for your space.
5. Reference a Furnace Size Chart
You can also compare your home’s square footage to a furnace size chart. There are a number of different furnace size charts out there. These charts give comparisons between home square footage and the BTUs needed to heat it. It’s not as accurate as calculating it yourself. Most charts follow guidelines similar to these:
- A 1,200-square-foot home will require between 35,000 and 75,000 BTUs
- A 1,500-square-foot home will require between 45,000 to 90,000 BTUs
- A 1,800-square-foot home will require between 55,000 to 110,000 BTUs
- A 2,100-square-foot home will require between 65,000 to 125,000 BTUs
- A 2,400-square-foot home will require between 75,000 to 145,000 BTUs
Expert Furnace Service and Installation in Los Angeles
If you’re interested in updating or upgrading your home’s furnace, give Mike Diamond a call. Our expert technicians can answer your questions about the make, model, and size of the perfect furnace for your home. We’ll be able to get your just right furnace installed quickly and efficiently.
Frequently Asked Furnace Sizing Questions
What type of furnace do I have?
While the make and model vary, it’s likely that you have a natural gas furnace installed in your home. In Los Angeles and across most of The U.S., gas furnaces are the most common way people heat their homes. You can identify a gas furnace by the gas line piped to it and the blue pilot flame inside. If you’re unsure, a technician from Mike Diamond will be happy to help you identify the type of furnace you have and give you suggestions for a replacement furnace.
What is BTU in furnace calculations?
BTU stands for British thermal units. It is a standard unit of measurement for determining how much heat energy you will need to warm your entire home. See the formula above to calculate how many BTU you need.
Can a furnace be too big for a house?
Yes. A furnace that is too big will have difficulty warming a home consistently. It will turn on and shut off frequently causing some areas to heat more than others. Having a furnace that’s too big costs more upfront and will cost more on your monthly utility bill.
Who installs the right size furnace in Los Angeles and Orange County?
You can trust Mike Diamond’s licensed technicians to select and install the right furnace for your home. We’ve been matching L.A. homeowners with the right appliances for nearly 50 years. We know what works best!
