How Big of a Furnace Do You Need for Your Minnesota Home?

“I want a warmer house, lower energy bill, and better working furnace. How do I get all of those things?” The perfect solution is to get a new furnace! A properly sized furnace should provide enough heat for your home, be more efficient for your bank account, and have a long lifespan.

So how do you get the ideal furnace size? Long story short, you need to contact a professional technician to find the appropriate size.

  • To help you understand why, we need to explain:
  • What furnace “size” means.
  • The negative effects of getting an oversized or undersized furnace.
  • The 5 major factors that affect the size you need.

What exactly is a furnace’s “size”?

You may have seen vague descriptions about furnace “size” on a manufacturer’s website, but what does it really mean?

Furnace size is measured in BTUs (British Thermal Unit) and measures the furnace’s thermal energy (heat) output. The more BTUs, the more heat it can deliver over a specific timeframe.

Now, here’s the important part: Bigger does not mean better.

Here’s why.

Why choosing the right furnace size is important

Choosing a furnace size is like a choosing a shoe size: If it’s too big or too small, you’ll have painful problems.

For example, an oversized furnace turns on and off frequently (short cycles) because it heats your home too quickly, causing the furnace to shut down, only to turn back on again once your home cools down.

Short cycling causes problems like:

  • More breakdowns/Shorter furnace lifespan
  • Cold spots in certain parts of your home
  • Increased energy bills

Conversely, an undersized furnace runs too much because it can’t supply enough heat to reach your desired temperature setting. Constantly running in this way causes problems like:

  • Decreased comfort
  • High energy bills
  • Overheated heat exchanger, which can cause the furnace to shut down

Now that you know that you can’t just pick a furnace size all willy nilly, let’s explain what goes into finding the furnace size you need.

Major factors that affect the furnace size you need

A HVAC contractor can easily determine the size you need through a Manual J calculation. This calculation will take into account multiple factors including (but not limited to):

  • The size of your home: The larger the home, the more heat you’d need to heat all the living spaces. So a bigger home needs a bigger furnace.
  • Geography: Minnesotans living in a harsh climate need a bigger furnace than Floridians.
  • The efficiency of the furnace: The more efficient the furnace, the smaller it can be.
  • Insulation: Under insulated homes lose more heat, meaning you’d need a larger furnace to compensate.
  • Home’s age: Older homes are leaky/drafty and are often under insulation. Meaning you need a larger furnace to compensate.  

Beware of contractors using a simple rule of thumb (size of your home) to guess your furnace size. These people just want your money—not what’s best for you.

Find the furnace size you need; contact a Minnesota tech

Here’s the best news of this article: You can find out the furnace size you need for free. Just contact a contractor for a free installation estimate.

If you live in Minnesota, we can provide that service for you ASAP!

Schedule a free installation estimate with On Time Service Pros.


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