Furnace service.

Design Air is your #1 HVAC contractor in Missoula, MT and the surrounding communities. We are the leading company for all of your heating needs. If you need repairs, maintenance, or a brand new system installed, the technicians at Design Air are the qualified and professional crew for the job.

We provide the highest quality service for your forced air furnace or heat pump. We also aim to educate and inform our customers. Informed decisions are good decisions. We want you to feel confident we are qualified to perform the service for which you are hiring us.

How Much Money Can a New Furnace Save You?

Our AFUE energy savings calculator can help determine how much you could save on your utility bills. Simply enter your current unit's AFUE value and compare it to a newer, more efficient system. You can even customize it to better match your home's system for a more accurate calculation.

AFUE Energy Savings Calculator

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This calculator does not guarantee actual costs or savings and is only to be used for educational purposes.

Customize to Your Home

Adjust these settings for a more accurate calculation:




Rate ($/Mcf)


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Historical Comparison

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** Data from U.S. Energy Information Administration
*** Data from 2002 EPA study

** Data for Canadian cities from nrcan.gc.ca
*** Data from weatherdatadepot.com

Furnace Repair

Don’t get left in the cold! Is your furnace acting up, blowing cold air, or making too much noise? Our experienced team of professionals is here to keep your home warm and cozy. We repair all makes and models, and we will never try to sell you a service that you don’t need. Our technicians are honest and hard working, and we’re always transparent and fair about the work we do.

Furnace Replacement

Sometimes a repair is not sufficient to fix your furnace. Sometimes a new furnace is the most cost-effective and energy-efficient way to go. We will always be honest with you about a possible furnace replacement. We value our time and your money––we don’t want to perform repairs or service on an appliance that is in need of replacement.

If you do need a furnace replacement, we know how overwhelming it can be. Here are some of the frequently asked questions about furnaces that we get from some of our Missoula, MT residents:

What Are The Different Types Of Furnaces?

Single Stage: A single-stage furnace has only one stage of operation. It can either be turned on or turned off.

Two Stage: A two-stage furnace has two settings––full and half speed. This is a more efficient way to heat and provides for better comfort, because it can move the air at a slower pace.

Variable Stage or Modulating: A variable-stage or modulating furnace modulates the speed and heat output based on the temperature outside and the desired comfort level. This furnace only works as much as you need it, making this type the most energy-efficient type of furnace.

What Is AFUE?

AFUE, or Annualized Fuel Utilization Efficiency, is a measure of furnace-heating efficiency. The higher the AFUE, the more efficient the furnace.

What Size Furnace Do I Need?

We can calculate the correct size furnace for your home. The number of BTUs, or British Thermal Units, needed to heat your home is dependent on a number of variables. Contrary to what you might think, a bigger furnace may not necessarily mean more heating power for your home. Call us at Design Air, and we can set up an appointment to calculate the furnace size you might need.

Gas Furnace Repair in Stevensville, MT 59870

“My main source of heat was not working during the coldest time this winter.I had two different heating companies try to fix it with no luck. Then I called design Air, they sent their technician Mark out and he fixed it swiftly. The office person Liz was very helpful. Also, I highly recommend Design Air.”
- Marc L.

Gas Furnace Installation in Lolo, 59847

“Tristan, Casey, and Will rock! They installed both furnace and air. They are professional, excellent communications throughout the day, and they found solutions whenever needed. I could not be more satisfied and I recommend Design Air and this crew 100%!”

- Roger M.

Gas Furnace Installation in Missoula, 59804

“Miles was our installer for an air conditioner unit and replacement furnace. He was professional and easy to have around during the days of installation. He showed up on time, answered any questions we had and put up with our lab wanting to play ball. So far, we are very happy we chose Designair.”

- Dawn K.

Gas Furnace Replacement in Missoula, 59802

“Very pleased with the whole team. Nate evaluation, Steve sales, Melisa communication, Miles and Will instillation; they were all friendly, polite, knowledgeable, and professional. Made a tough time easier. Thank you all. Stay safe.
John and Karen”

- John R.

Gas Furnace Installation in Missoula, 59803

“Miles and Cody arrived promptly to my home; were clean, organized and friendly. They explained what they would be doing, answered all my questions and updated me along the way. Before I knew it, the new gas furnace was installed and running smoothly. I highly recommend these guys to anyone – they are extremely professional. Thanks Design Air!”

- Amy S.

Need Furnace Service?

Contact the experts at Design Air.

Call us at 406-251-7997!