Voted Duluth’s Best of the best plumbing contractor!

Trusted Professionals

For the past 80 years A.G. O’Brien has led the Northland in providing the highest quality services in Plumbing, HVAC, and Fire Protection.

We pride ourselves in doing work that is second to none, and our portfolio includes projects for the area’s biggest businesses and community leaders, including:

UMD, Cirrus, KwikTrip, St. Scholastica, Essentia Health, Clyde iron works, Fond Du Lac Band, Lake superior college, Members Co-op credit union, Holy rosary church and campus.

A.G. O’Brien Services


We have extensive experience installing and maintaining commercial & residential plumbing. We also test, fix, and replace both residential & commercial backflow preventers.


We pride ourselves on installing and maintaining the most cost-effective HVAC systems.

Fire protection

We install many types of fire protection systems in both residential & commercial properties.

Air purification technology

We install air purifying bipolar ionization technology in both residential & commercial properties to help keep air clean and safe.

Honest Reviews

I have used A.G. O’Brien several times for my cabin. They were  very professional, timely, and upfront with cost. They have replaced a toilet, fixed a frozen sink, installed a new boiler and water heater, and plumbed in our gas for a new fireplace. I will definitely use them in the future.


“Treated our church building like it was their own home. Installation was a high efficiency system that runs perfectly. Amazing craftsmanship, planning, estimation came in under budget.”

Business owner