Furnaces aren’t one size fits all. They come in many sizes depending on your home and preferences. Here is everything you need to know about choosing the right size furnace for your home:
TL;DR
Choosing the right furnace size is important for both comfort and energy efficiency. If your furnace is too small, it won’t heat your home properly, and your energy bills will increase. If it’s too large, it will cycle on and off frequently, wasting energy. The correct size depends on factors like your home’s size, insulation, and climate. Online calculators can give a rough estimate, but it’s often best to consult a professional for the most accurate recommendation. Getting the right size from the start can save you time and money in the long run.
Understanding Furnace Size Classes
Furnaces are not classified in the traditional small, medium, or large sizes. Instead, they are classified on the BTU rating, efficiency rating, fuel type, etc.
BTU Rating
The BTU rating indicates the furnace’s heating capacity. This is the most common way to classify a furnace size.
BTU stands for British Thermal Rating. A higher BTU rating means the furnace can fit into larger homes.
- Less than 40,000 BTU furnaces are suitable for small apartments or single rooms.
- BTU ratings between 40,000 and 80,000 are ideal for homes with two to three bedrooms.
- Larger homes with multiple stories may require a BTU rating higher than 80,000.
Efficiency Rating
Furnaces can be rated by how much they convert the consumed power into heat. A higher rating means more heat with the same electricity or power.
Most standard furnaces have around 80% rating. High-efficiency furnaces have 80-90% ratings. Over 90% rated furnaces are ultra-high efficient ones.
Fuel Types
Furnaces can also be classified by the fuel type they use. A furnace can use different types of fuel including gas, electricity, oil, and even wooden pallets.
Each has its own advantages and disadvantages. The best fuel type depends on your needs and preferences. Consult with an HVAC professional before making an informed decision.
The Importance of Proper Furnace Size
Furnace models can be quite lucrative. But not all furnaces fit all homes.
What happens when you don’t pick the proper furnace size?
- If the furnace is too small, the heating will be uneven. The energy bills will be high because of inefficiencies and overheating. The components, or the furnace itself might break down more often.
- Larger furnaces will run for less time (switching on and off) and overheat the rooms. The energy bill will still be higher because of the constant on and off.
Calculating the Right Furnace Size:
The most simplified guideline, if you don’t know where to start, is: 30 BTU of furnace energy rating per square ft of home it will heat.
For example, if you have a 1,000 square feet home, you need a 30,000 BTU furnace. For a 2,000 square ft. home, get something around 60,000 BTU.
This is not a hard and fast rule. The number can hugely vary on different factors like the climate, insulation, window efficiency, the number of occupants living, etc.
For a more accurate number, follow these methods:
Manual J Load Calculation
This calculation considers factors like
- Climate
- Insulation
- Windows
- Air filtration
- Occupancy
- Internal heat sources
- Area occupied
By considering these factors, this calculation provides an estimate.
The load calculation can be complex. You need to measure the parameters yourself and use different J load calculators online.
Online Calculators
There are different online calculators available for a rough estimate of your furnace’s energy requirements.
You need less data measurement and the process is quick. But the number won’t be as accurate as the Manual J calculation.
Consulting HVAC Professionals
Of course, professionals are always there for your inquiries. You can seek out an expert’s help if you are still not sure or confident about what you need. They can perform a thorough analysis of your home and recommend the ideal furnace size based on their expertise.
Not sure what furnace size you need? Licensed and trained professionals at The Chill Brothers are always ready with solutions to your HVAC problems, including furnace sizing. Their service includes HVAC repairs in Magnolia with other areas across the States.
Factors Influencing Furnace Sizing
We have already mentioned the number requirement for the correct furnace size isn’t fixed. Because the furnace size depends on a wide range of factors, such as:
1. Square Footage
30 BTU per square foot of home is a general estimate. But this just gives you a starting point.
An accurate measurement includes a finished basement, attics, and other heated spaces with the proper sizing of your home.
The layout of your home is also important. Because open floor plans can distribute the heat more evenly. Closed-off spaces require additional heating capacity.
2. Insulation and Windows
Well-insulated homes may need a smaller furnace, as they retain heat more effectively. Many houses already have different insulation in place. While some houses don’t have any additional systems for insulation.
Different window types can be a factor for insulation and heating requirements. For example, a double-pane or triple-pane window is more efficient than a single-pane window.
While checking for proper insulation, you will also want to note any cracks in windows and doors as this will affect the efficiency of your furnace.
3. Climate
The amount of heating load your furnace needs to handle depends on the HDD. HDD stands for Heating Degree Days.
HDD is the measurement of how cold the temperature is on a given day. A high HDD means a colder climate. And so the furnace needs to be as powerful.
If your home is in an area with high winds, you will experience a higher heat loss. This situation also requires a larger furnace.
4. Ceilings
A taller ceiling means a larger area to heat. This requires a more powerful furnace.
The same goes for multiple-story homes. In addition to the volumes, there are also potential for heat losses between floors.
Mistakes to Avoid:
Guessing: Guessing the size can lead to getting the wrong size system.
Ignoring Insulation: Insulation is needed to keep the home warm. If you do not have the proper amount, it will release the heat quickly and make the system work extra hard to keep up.
Are you ready to upgrade your furnace? Upgrade with The Chill Brothers and you can receive up to $2,000 for your old furnace! Give them a call for more information.
By taking all these points into consideration, you can start to feel the warmth! If you are needed any help with your furnace, let The Chill Brothers help you out!
I’m Francis Kaspar, a 35-year-old HVAC technician with over 10 years of experience in the industry. I hold a certification in HVAC technology from Texas State Technical College, where I gained hands-on skills that shaped my career.
Currently, I’m working at The Chill Brothers, specializing in AC installation, repair, and energy-efficient solutions. Outside of work, I enjoy spending time with my wife and two kids.
I’m also passionate about sharing my HVAC knowledge written by articles that provide practical tips and tricks for homeowners.
