Brennan Heating & Cooling Inc. in Great Falls, MT

Brennan Heating & Cooling Inc. in Great Falls, MT At Brennan Heating we offer a variety of HVAC services to homeowners and commercial businesses. We We are proud to serve Great Falls and the surrounding area.

Brennan Heating & Cooling in Great Falls, MT has been in business over 30 years. It is a family owned business with Billy, Pat and Dave Brennan at the helm. We have a great crew ready to take care of our customers HVAC systems and custom sheet metal. Give us a call. 406-452-1133

Our Approach
We are known for our high quality workmanship, reliability, and personal attention to each customer’s job

. All owners are involved in their projects from beginning to end, in both the design and installation phases. Our Story
Brennan Heating and Cooling was established in June of 1990 by Billy Brennan. Billy’s two brothers, Dave and Pat joined Billy in the early 1990’s. Bill Brennan, father of the three brothers, started B&B Heating in February 1977 passing down the sheet metal tradition. Billy earned his Associated Mechanical Engineering Degree from Northern Havre in 1978 and an HVAC Design Certificate from Dunwoody Institute in Minneapolis, MN in 1980. Dave graduated from Montana State University in 1987 with a Mechanical Engineering Degree. Pat’s degree was in Mechanical Engineering Technology also from Montana State University in 1991. Meet the Team
Billy, Dave and Pat Brennan are the Officers and Owners of Brennan Heating and Cooling Inc. Each one is involved in the community and loves being active and in the outdoors when not working on the various business aspects of running a busy company.

Cleaning Mitsubishi Mini-Split FiltersTurn the unit off. Turn the Mitsubishi indoor unit off before opening the front co...
08/15/2026

Cleaning Mitsubishi Mini-Split Filters

Turn the unit off. Turn the Mitsubishi indoor unit off before opening the front cover.

Lift the front cover. Gently raise the large front panel until it stays open.

Remove the blue mesh filters. The two blue filters slide/lift out of the indoor unit. Be gentle with the plastic frames so they aren't bent or cracked.

Check how dirty they are.You can see the dust collected across the mesh. A dirty filter reduces airflow and can affect heating and cooling performance.
Vacuum off loose dust first. A vacuum with a soft brush attachment works well and keeps a lot of the dirt from going down the drain.

Wash the filters. Rinse them with lukewarm water. If necessary, use a small amount of mild detergent. Avoid harsh cleaners, scrubbing hard, or very hot water because the mesh and plastic frame can be damaged.

Allow them to dry completely. Let them air-dry out of direct high heat. Do not reinstall them dripping wet.

Reinstall the filters. Slide each clean, dry filter back into its original position, making sure it is seated correctly.

Close the front cover and turn the unit back on.

These filters are washable and reusable—they normally do not need to be replaced every time they get dirty.

Check it regularly, especially during periods of heavy heating or cooling, construction dust, wildfire smoke, or in homes with pets.

Change your furnace filters, folks!If you have ever called me at the office because your home has no heat or no cooling,...
08/02/2026

Change your furnace filters, folks!

If you have ever called me at the office because your home has no heat or no cooling, you were most likely asked about your furnace filter—when it was last changed or, in my case, when the electrostatic filter was last washed.

The type of filter matters too. Many people buy filters with a MERV rating that is too restrictive for their system. In many cases, it is better to use a lower-MERV filter and replace it more often than to make your furnace or air conditioner struggle to pull air through a heavily restrictive filter.

I have two washable electrostatic filters that I rotate monthly. I remove the dirty one, vacuum it, wash it thoroughly and let it dry completely. I install the clean spare, then set the washed one aside for the following month.

I had changed this filter just last month, but a new house was built next door and all the construction and landscaping stirred up a tremendous amount of dirt. Add shedding animals, and my filter was a mess. Imagine what it might have looked like if I had waited several months—or waited until the system quit working.

Next on my list is washing out the outdoor condenser because much of that dirt was blowing around while my air conditioner was running.
Even when a pleated filter appears clean, hold it up to a light. By the time many pleated filters visibly look dirty, they may already be badly restricted.

A clean filter helps your system breathe, improves airflow and may prevent unnecessary service calls. Check it regularly—not just when the furnace or air conditioner stops working.

The last few weeks have been a hot one not letting up soon. Please make sure you have a clean filter in your system. It...
07/24/2026

The last few weeks have been a hot one not letting up soon. Please make sure you have a clean filter in your system. It is best during these very hot days to keep your thermostat on cooling. If you shut ac off at night your system will struggle. It is faster to heat cold air than cool hot air.
Pull shades on sunny side of house.
Stay cool and hydrated.

Well it has been hot outside and apparently 🔥 inside as well.
07/15/2026

Well it has been hot outside and apparently 🔥 inside as well.

04/07/2026

If you live in the area around Lincoln School and you have the insulation in your yard. Check your furnace intake for the insulation. We replaced a furnace today and guess what it was full of.

06/13/2025

Cottonwood flying around like crazy. Please gently wash it out of your outside condenser so your air conditioner works properly

04/24/2025

Video walk thru of the ductwork.

Work in progress. The air you breathe and the conditioning either heating or cooling isn't the thing you usually see in ...
04/24/2025

Work in progress. The air you breathe and the conditioning either heating or cooling isn't the thing you usually see in a home but it is so important to your health and comfort. Make sure the company you use for your projects understands this and does the job the right way.

02/20/2025

We have had some "Snow Birds" leave for some time this winter. They have set their thermostat too low causing some furnaces to freeze up.

With the freezing weather WE recommend 65 degrees set on your thermostat.

From the Manufacturer - No lower than 60 on set-back for Return Air.

The Why - The secondary heat exchanger is designed to handle acidic condensate. The primary is not intended to handle condensate and lower RA temps may cause condensate to form there, causing premature failure in the primary heat exchanger.

Address

815 21st Street NW
Great Falls, MT
59404

Opening Hours

Monday 8am - 4:30pm
Tuesday 8am - 4:30pm
Wednesday 8am - 4:30pm
Thursday 8am - 4:30pm
Friday 8am - 4:30pm

Telephone

+14064521133

Website

Alerts

Be the first to know and let us send you an email when Brennan Heating & Cooling Inc. in Great Falls, MT posts news and promotions. Your email address will not be used for any other purpose, and you can unsubscribe at any time.

Shortcuts

Share

Category