SOUTHEAST WISCONSIN’S HVAC EXPERTS

ESTABLISHED IN 1962

OUR STORY

Continuing a Tradition of Exceptional Heating and Cooling Services

What began in a garage in 1962—with Gordy and John Cole’s commitment to offering honest, high quality HVAC service—continues today at Interstate Heating Co. in Sussex. We’ve grown to offer the latest heating, cooling, and air quality products, and our service area now covers all of southeastern Wisconsin.

We are three generations strong and still follow the most basic rule of business: we treat our customers the way we want to be treated.

About Us

WHAT OUR CUSTOMERS ARE SAYING

Google Rating

4.9

Based on 925 reviews

Interstate Heating Co., Inc.

4.9

Jagjit Kaur

21:44 30 Jan 26

I have seen a steady decline in Interstate Heating Sussex WI since Tom the old owner sold the company.My home project took nearly five years to complete. Throughout this period, delays were repeatedly blamed on ownership changes, COVID, part unavailability, missing components, and the use of non standard parts that Tom’s company decided to use.Despite paying over $60,000, my home project was never properly finished. I was eventually pressured to settle with unfinished work. After that, I was informed that there were no warranties covering the work performed.Key issues I experienced:• Poor and incomplete finishing• Warranties were never registered, and I was never informed that failure to register them directly with Carrier would reduce the warranty period by half• Use of non-standard parts• Rude and unprofessional email communication from employees• Consistent lack of communication• Noticeable change in employee attitude after payment was made• Voicemails and emails frequently ignoredIn the end, I had to hire another company to correct and complete the work that was originally paid for.This is the first time I have ever written a public review, but the experience left me no choice. I have shared detailed reviews on YouTube, the BBB, and with consumer protection agencies so others can make an informed decision.

John Mangold

20:31 30 Jan 26

Eric did a complete checkup and identified the issues in a timely fashion. Would recommend Eric and the company for any other needed repairs or purchasers.

R M

22:23 29 Jan 26

We had a new furnace with a bad gasket, causing water to leak beneath the unit, and rust inside it as well. Tristan was courteous, helpful, prompt, and friendly. We could tell that he cared a lot about getting the job done right, and he patiently answered all our questions. Great service and great technician.

Brett M

19:19 27 Jan 26

Emergency call for no heat was responded to Very Quickly. Thank you Ellen.

Gary McMurray

19:54 26 Jan 26

Very knowledgeable and exhibited a true understanding of the problem.

Thomas Gerger

18:38 26 Jan 26

Tristan was great!! Very personable and qualified. Answered all my questions too! Tom Gerger. That was Nov. 2025. Now today, Jan. 26,2026, Eric O. came to analyze a major problem with our furnace. Eric originally installed our Carrier system for us in 2007! He's extremely thorough and friendly. Turns out a new furnace makes a lot more sense than putting money into the old one. Very thrilled that Interstate will install the new unit tomorrow morning. Our fireplaces and electric space heaters have been running since late Saturday morning! Tom Gerger

James O'Laughlin

16:31 26 Jan 26

As the weather has been extremely cold -20's and -30's, all HVAC contractors are swamped. The Interstate Heating team has the man power to adapt to any situation. Very professional, on time and always a pleasure working with their team.Jim

Jill Sweitzer

15:45 26 Jan 26

Mark

13:48 26 Jan 26

The men who came out were wonderful, courteous, professional, explained things, and were polite. They did a great job!The cost was unbelievable. We paid $600 for a person to come out here just to tell us we needed a new furnace. That is outrageous!And the emergency service is hardly that at all. Your store/shop did not have the part we needed to fix the furnace long enough for us to be warm until the next day when the furnace could be replaced. So we did the best we could to stay warm and were without heat from 5pm to 8am the next day. But we paid for a service that basically doesn’t exist.This is no reflection on the three men who came out. It is an evaluation of the company policy or lack thereof. These three people were the only reason we continued with you.I’m highly disappointed. But kudos to the three who were here.Dr. Mark Amundsen

Brittney

18:24 23 Jan 26

dana gilboy

21:44 20 Jan 26

Great service from Interstate! Tristan performed standard furnace check and maintenance. Very professional and informative.

Carrie Jaskaniec

13:50 17 Jan 26

Tristan was on time, friendly, helpful, cleaned up when finished and I would highly recommend him as a technician!

Joseph Bingen

21:21 15 Jan 26

Dillon was prompt, courteous and worked at correcting thingd

Patti Sprague

18:38 15 Jan 26

Eric was professional and he was quick and honest. Seeing that my furnace is 38 years old I'm sure it's time for a new one and that's exactly what he told me.

Tara Salaks

15:04 15 Jan 26

Very fast and great customer service. Chris is great!

G Schmeling

20:41 14 Jan 26

Highly recommend. Have used them for 30+ years

00:59 14 Jan 26

Tristan did a thorough job maintaining my furnace. During the routine maintenance, he discovered an issue with the furnace inducer motor (bad bearing) and worked with me to file the warranty claim. Thanks for the great service, Tristan! Now my furnace is running in tip top shape again.

Neal OReilly

16:53 09 Jan 26

Professional and very informative.

Angie

17:42 08 Jan 26

Elaine Hills

14:51 07 Jan 26

Last Thursday Eric, the Interstate technician, was at my home for the annual furnace check-up. He discovered a failed inducer, which he explained would result in zero heat. He also found two zone dampers that were making noises indicating failure was coming soon. Eric explained how the dampers work and why they are needed as well for adequate, even heating throughout the home. He ordered the needed parts and less than a week later all parts are replaced and everything is in perfect working order for another Wisconsin winter season. The professionalism, knowledge and promptness with Interstate Heating is at the highest level. I have never been disappointed.

Linda Pitts

01:44 07 Jan 26

Dylan was prompt and very professional!!!! Great young man!!!!

Matthew Baker

00:48 03 Jan 26

Informative and professional. Did great work and cleaned things up.

1neilandkaren

21:00 02 Jan 26

⭐⭐⭐⭐⭐I called the morning after a holiday and Matthew was very helpful in getting us the support we needed. Chris arrived a little early and quickly diagnosed the issues with both our boiler and furnace. He was polite, knowledgeable, efficient, and cleaned up after finishing the work.We’ve worked with Interstate Heating multiple times, and they are always responsive and helpful—from the office staff to the technicians. They are honest and genuinely want what’s best for their customers. Highly recommend!

Karl Fritchen

17:51 02 Jan 26

Tristan did an awesome job! He communicated well about when he was going to arrive and then called me after the visit to outline what he had done and the costs related to it. Very positive experience and very professional technician.

Kathy Kowalski

00:01 01 Jan 26

Excellent prompt service.Technician found the issue quickly!

Harry Aghjian

17:26 31 Dec 25

Great service tech and solved the issue quickly… Tristen was awesome!

Julie Offutt

16:58 31 Dec 25

Tristan was amazing. He advised me to close vents/redirect air to the rooms that needed more heat and to leave on the fan to protect our HVAC system: : : he did suggest adding a line to the basement to give more heat as well which we will likely do.He was an extremely knowledgeable, skilled and kind service man : thank you-Julianne

Bill Hansen

18:00 30 Dec 25

Technician was on time and thorough. Very bright and articulate. A great ambassador to your organization. Thank you Tristen!

Chris Peterson

21:51 29 Dec 25

Melody Ruhbusch

17:13 26 Dec 25

Considering this was the day after Christmas we were grateful that Jason was available to assist us with our problem. He was very friendly and informative. Explained our options without any pressure.

Phil Prange

19:27 23 Dec 25

The technician arrived early. He was clean, courteous, and competent.My heating issue was resolved quickly and explained well.Can't say enough good things about Interstate and their service team.Chris was excellent.Thank you

Joanne Nolde

21:17 22 Dec 25

Antonio and his team installed a new furnace. They were knowledgeable, on task, and efficient in removing the old furnace, replacing the new one, and cleaning up before leaving. They were friendly, polite, and articulate in explaining what they were doing and answering my questions. I would definitely recommend them to others.

Karen Wright

20:20 18 Dec 25

I trust Interstate Heating. We have used them for27 years. Tristen was very thorough and figured out why were not getting heat in our bedroom.It all boiled down to a small part that had to be replaced. He was very diligent in finding the problem. He was great!!!! He also explained everything to me.A big thank you to Tristen

Bubba John

15:05 18 Dec 25

Eric installed a Aprilaire humidifier for us. He did a great job and we are very happy with it. The service was awesome and we highly recommend Interstate Heating.

Kathy miller

14:26 18 Dec 25

technicians showed up on time, laid down cloth on the traffic patten to the basement as it was a messy, sloppy day. stated it would be about a 4 hour install which was pretty accurate. afterwords they cleaned up everything and could not even tell they were here.

Tom Gannon

20:31 17 Dec 25

Eric does a great job. He is extremely knowledgeable and is an excellent communicator.

Harry Clayton

16:42 17 Dec 25

On-time and worked clean and efficiently.The garage heater Turned out better than I anticipated!

Kathy Greb

20:11 16 Dec 25

Chris completed annual maintenance on my furnace and humidifier. Very efficient, pleasant and answered all my questions.

Jack B

20:02 16 Dec 25

Chris did our furnace maintenance today. He answered all of my questions and provided good suggestions for moving forward.

david carlson

19:54 16 Dec 25

Tristan did a great job. He explained everything thoroughly. He was extremely polite.

Pedro Pierri

17:51 16 Dec 25

Furnace gave out after 15 years in one of the coldest days of the year. Interstate Heating was able to expedite the repair, get the part that was not readily available and complete the repair it on the same day. We have heat again! The technician that came in, Dylan, did an excellent job in repairing the problem and explaining what happened, how he was going to fix it and I even learned something new. I highly recommend their services.

Mary Lou Moths

01:02 16 Dec 25

ETHAN Lipski is a great employee. He is polite, respectful, and efficient. He takes time to answer my questions. 5 srars, for sure!

SANDRA ROBACK

21:14 15 Dec 25

Wonderful team- customer service (Mathew) and their service technician Eric were both outstanding to work with. Eric's knowledge and his ability to get our furnace working in matter of 1.5!!

LBRC Account

17:39 15 Dec 25

The service was quick and efficient. They always provide top tier service. They are my definition of being very professional. Highly recommended.

Kurt Farrell

13:56 14 Dec 25

Our boiler went out on one of the coldest days yet in 2025. I called Interstate Heating because they were a dealer for Buterus, the brand of boiler that we were using. I promptly received a call back from Tristan Garland who was on-call for the weekend who professional and courteous. We walked through a few diagnostics and Tristan quickly came to the conclusion the the ignitor was probably the culprit for the boiler not starting up. Within the hour Tristan has procured the parts from his shop and was at our house installing the parts. Within 30 minutes all was back up and running and we had heat!He was professional and I would recommend him and Interstate for all your HVAC needs.Thanks Tristan!

Brent DesRoches

13:41 13 Dec 25

Interstate Heating replaced our 21 year old furnace and a/c with a Carrier cold climate heat pump and high efficiency gas furnace. I worked with Tom from sales to get a good balance of price and efficient equipment. He did a great job working through different options to show different price points. The install crew also did a great job. They laid down drop cloths to protect the wood floor and carpeting and they cleaned up well after the work was complete. The equipment installation and duct modifications look very well put together.

Ruth Hau

12:01 13 Dec 25

Great job, Scott was on time and very professional.

Jim Sawyer

23:06 10 Dec 25

Tristan was able to explain exactly what was needed and provided a very thorough service of our furnace. I would highly recommend them and will continue to use them for our Hvac system.

James Long

21:30 10 Dec 25

Courtesy, knowledgeable, explained what he was going to do and reviewed with me what he did

Cynthia Pares

16:36 10 Dec 25

Eric is wonderful!

J W

23:55 09 Dec 25

Tristan was highly knowledgeable and courteous. Possesses a high skill level, superior troubleshooting abilities and checked multiple system functions with various diagnostic tools. Went above and beyond to make sure everything was running properly. Great customer service throughout too.

mark waraksa

20:58 09 Dec 25

Nice gentlemen came to help me on the thermostat

Jim Wollin

20:53 09 Dec 25

Excellent service knowledgeable polite, service done in timely fashion. Would recommend him and his partner

Susan Eng

00:30 06 Dec 25

The pro did an excellent job of diagnosing the problem with my furnace.Im not happy with the warranty on the furnace, the furnace is only a little over one year old and the Carrier warranty only covered the cost of parts and not the labor which was $489.55! It seems a warranty should be better than this for a relatively new furnace. Also it seems that the problem with the furnace is one that occurs frequently and may occur again. It seems to me that the thermostat recommended by your company from the furnace company has more issues than my Nest thermostat which governs my other furnace just fine. If I require further service, i think changing the thermostat seems to be a better plan!

Chip Losee

20:26 05 Dec 25

Very satisfied, Tristan was awesome. Very professional and knowledgeable.

Amy De La Cerda

20:04 05 Dec 25

Interstate was amazing. From the empathy and friendly manner my initial call was handled, to the thorough way Eric explained what was happening, to our install, everyone was super polite, respectful, and did great job. Victor and his partner for the install laid down tarps and wore shoe covers to keep the pathway clean and even took extra steps to clean up the rust stains on the floor from the old unit. They also took the time to help us get familiar with our new thermostat.

Diane Zore

17:55 05 Dec 25

Tristan was here and fixed the issue, was professional and competent. We have been customers for over 25 years and rely on your company to always do your best!

Joseph Otu

02:10 05 Dec 25

Eric was very knowledgeable, detailed, and professional. He explained what was wrong and what he did. I was very pleased.

Kathleen Dubiel

02:04 05 Dec 25

All was pleasant. I did pay cash and without receiving a receipt felt odd but was sent the reciept via email!

Sally Fritz

21:29 04 Dec 25

We’re very grateful that the 2 gentlemen pursued the problem since of course when they got here the furnace appeared fine! They found a large birds nest in the intake pipe!Very happy with their service!

keepSmiling

23:13 03 Dec 25

Joy Stein

15:45 03 Dec 25

Diane Brunclik

22:35 02 Dec 25

Austin was courteous and professional

Terry Flanagan

23:56 26 Nov 25

Our service technician was very detailed oriented and kept us informed at every step of what he was doing and his findings. Excellent service !

Bob Kachelek

01:30 26 Nov 25

Very friendly, explained everything he was doing. Knowledgeable and gave us good maintenance tips on our furnace and AC.

Gerardo Caballero

17:55 25 Nov 25

John Beauchamp

00:20 25 Nov 25

Eric did an excellent job in diagnosing and repairing the HVAC unit. Thank you for the great service!

Nicole Smith

22:03 24 Nov 25

Tyler was very knowledgeable and polite when doing regular maintenance on my furnace today. Great job!

Julie T-V

20:32 21 Nov 25

They were neat, on time and fantastic to work with!

Carlene Wade

13:19 21 Nov 25

Great customer service!! Antonio was very professional and they did an awesome job. Cleaned up very well after they finished. We are very pleased!!

mary muntner

22:05 19 Nov 25

Trysten was very professional and knowledgeable. He was very pleasant and obliging. I would certainly like to have him do the work I have when i am ready. He is definitely an asset to Interstate.

anthony corrao

16:58 14 Nov 25

Tristin was very thorough and professional!

Christine Jahncke

15:32 14 Nov 25

Josh did an excellent job diagnosing the worn out part on my furnace and was great communicating with me during the repair. Thanks Josh for all your hard work and for making my home nice and warm again!

Wayne & Mary Jo Koch

00:48 13 Nov 25

Josh did his always excellent job on our biennial furnace check up.

Dave Goss

19:57 10 Nov 25

Josh from Interstate Heating did a very thorough job of investigating why our furnace stopped working in the middle of the night. He did have to order a new part and will return tomorrow afternoon to install it.He checked a number of things on the furnace to make sure everything was working correctly!

Michael Cieslewicz

21:30 07 Nov 25

Dylan has provided service to us one previous time. He is always courteous, efficient and knowledgeable.

Craig Hurst

19:58 07 Nov 25

Interstate has been servicing our HVAC for several years. The technicians are always courteous and professional.

michael phillips

17:44 07 Nov 25

very polite and was able to correct our condensate pump problem

don mantz

15:04 04 Nov 25

Eric Osterman is always a pleasure to work with. He knows the heating business and communicates well. He completes the project in a professional manner and reviews what he did with us. Top member of your team.

gwen medved

19:34 03 Nov 25

Justin was great! We have worked w Interstate for multiple properties for over 20 years. Per usual, great service, very informative, did HVAC maintenance, replaced filter, checked C02 levels and checked my equipment on main floor as well. Looking forward to my UV light, air purification and dehumidifier being installed next week!

Leonard Lutzke

20:02 31 Oct 25

Techs know their business well.

Jim Quinlan

14:45 31 Oct 25

Job completed quickly and professionally

John Heinrich

23:05 29 Oct 25

Debra Dixon

23:28 28 Oct 25

Good experience, gave good instructions and advice.

Greg Lutz

20:53 28 Oct 25

Josh is amazing. He is always able to figure out what is going on and I never feel like he is trying to sell me something I don’t need. It’s great to have that trust and confidence. And, he is a really good man who cares.

Katie Knudsen

14:09 28 Oct 25

Excellent service. On time with great communication on arrival time. In addition to annual furnace maintenance - a humidifier was added. I was very happy with the installation!

David Smith

21:55 27 Oct 25

Great

Joan Gertel

16:41 26 Oct 25

Kevin gets five stars

The Commish

15:19 23 Oct 25

They were fast to respond and schedule. The technician was very knowledgeable, helpful, and provided great details and recommendations. Overall price seemed a bit high but not outrageous. Will definitely do business with them again.

Sandy Jere

15:15 23 Oct 25

Peter Peterson

18:37 22 Oct 25

Chris did a wonderful job. With his kmowledge we trusted his recommendation as to what was needed.

David Felder

18:00 21 Oct 25

Dylan, was very professional. Tried to break the cost of the new part gently to me. But over $1, 500.00 is a hard number to swallow for a 11 year old furnace. I think carrier is off of my list for my next furnace and AC.

Kristin Troy

00:04 18 Oct 25

They came to fix a blower on the furnace which was unhooked by one of their employees during their routine maintenance appt. They hooked it up and charged us for a visit. Poor business practice.

Robert Gagliano

23:49 17 Oct 25

Dylan came to service our furnace and was on time, very professional & answered all of our questions and very informative and knowledgeable about the furnace and the issues. It was really a good experience. We will request him in the future. Our thanks also to Jake the Service Mgr.,along with Ellen & Jessica in the office. All very helpful. Great experience.

Robert

15:22 17 Oct 25

Excellent service and support, I will request Dylan for all of my services

Thomas Spleas

14:11 16 Oct 25

STEVE FRANCAVIGLIA

00:21 16 Oct 25

Eric was professional, knowledgeable, informative and talk time to teach.

Cedric Mays

19:46 15 Oct 25

Great service.

Jeana Holt

19:53 07 Oct 25

Tristen did a phenomenal job communicating with my husband and I throughout the HVAC system maintenance visit. He ensured that we both understood the implication of his recommendations and potential cost if/when we choose to have something repaired. I HIGHLY recommend Interstate Heating Co., there service always exceeds my expectations.

Aaron Holt

19:10 07 Oct 25

Tristan was awesome. Timely, thorough and great communication throughout!

See all reviews Write a review

“Tristan did a phenomenal job fixing my furnace and wall thermostat. He was very friendly and informative!”

- Nathan P.

“The team of Antonio Stanisch was very professional and courteous. They answered all my questions and walked me through the process. They also took all precautions to not damage any floors and left our place clean.”

- Johannes S.

“Tristan once again gave us excellent service. He was very informative, explaining what needed to be done and what he did. He even provided photos. We are very satisfied.”

- Mike G.