Blog

Are you looking for help with projects around the house? Our blog offers helpful tips and DIY videos, or schedule a service appointment today.

BTU Calculator: What Size Furnace Do I Need?

BTU calculator

If you’re a homeowner asking yourself “What size furnace do I need?” —you’ve come to the right place! A helpful tool to help you determine this is a BTU calculator, which is essentially just a furnace size calculator. By plugging in a number of factors about your home, this BTU calculator will determine how many British Thermal Units (BTU) per hour are needed for your furnace to run. This will help inform your decision about the size of your furnace when it comes time to purchase.

 

What Is A BTU?

A BTU is a traditional measurement unit of heat or energy, much like joules or watts. A furnace’s size determines on how much heat it can produce in an hour. One BTU represents the energy needed to heat a single pound of water by one degree Fahrenheit.

A single BTU is equivalent to 1,055 joules, 252 calories, or the energy released by burning one match.

The higher the number of BTUs your furnace requires, the more expensive your utility bill will be. This is because more energy is needed for heating or cooling your home.

However, if you know the exact number of BTUs needed to heat your home, you can cut costs. This is because if you are using the proper amount of heat, so you won’t be wasting energy, which translates to more money in your pocket.

What To Plug Into The Calculator

The furnace size calculator will you ask you to enter several measurements. These include: the room/house width, the room/house length, the ceiling height, the current condition of the room/house’s insulation, and the desired temperature increase or decrease. It’s very important to enter accurate dimensions so that the BTU calculator can provide you with the most precise numbers.

How To Calculate Temperature Change In Your Home

When plugging your desired temperature increase or decrease into the BTU calculator, simple math is required. First, look up the average temperature outside. Let’s say it’s 40 degrees Fahrenheit. If you want your indoor temperature to be, say, 72 degrees Fahrenheit, then you would find the difference between those two numbers. In this case, you would plug in 32 degrees Fahrenheit. Make sure you specify whether you are measuring in Fahrenheit or Celsius.

Other Factors Impacting Furnace Size

Despite needing to know your house’s dimensions, its current state of insulation and the desired temperature increase or decrease, you should be aware of other factors that may contribute to the best furnace size for your home. These factors may include:

  • Presence of windows
  • Number of residents (the more people, the more body heat there is)
  • Age of your home
  • Ductwork
  • Ceiling fans
  • Your home’s exposure to sunlight

While these elements cannot be plugged into a calculator, it’s important to keep them in mind as they may have an affect on which size furnace is best for your home.

Indicators Your Furnace Is The Wrong Size

If you’re having issues with your current furnace, it’s possible it’s the wrong size. While calculating the BTU is certainly the most accurate way to measure the best furnace size for your home, you can get a general feel if you need a bigger or smaller one based on a few factors.

Indicators That Your Furnace May Be Too Big

Indicators That Your Furnace May Be Too Small

  • Your house is cold even with the heat turned on, or has cold pockets.
  • A small furnace will overcompensate by running constantly, meaning your heating bills will be costly (although less so than a furnace that’s too big).
  • The furnace may burn out quickly due to constantly being on.

 

Better Size, Bigger Savings

Furnaces are efficient, affordable, and reliable — but only if they work properly. To save energy, money and avoid discomfort, make an informed decision by using a furnace size calculator and discover the number of BTUs needed for your furnace to run satisfactorily.

If you would like your furnace inspected for efficiency, or want further advice on the best furnace size for your home, schedule an appointment with the trained service professionals at John C. Flood. You can also contact us regarding HVAC, or energy saving tips.