I just really appreciated what seems like an honest assessment. I was looking for a second opinion,…read morebecause two other companies had recommended major, costly repairs or replacement for my gas furnace. The Grenz folks came, carefully looked at the unit, and said, "If it were my furnace, I wouldn't do anything. It is running the way it's supposed to." This second opinion cost me something, naturally, but it also saved me between $5,500 and $19,500 (two quotes from the other two companies). Jim seems like a straight shooter. I'd recommend you give these folks a try.

He called me back and talked me through the fix. He did not wait to come out and wouldn't take any…read morepayment for his assistance. He clearly knew what he was doing. He was able to talk me through several troubleshooting exercises without seeing the gas fireplace itself. If I have any HVAC or fireplace needs in the future, I will definitely use Grenz

We had a new furnace installed in 2023 and a new air conditioner in 2024. We signed up for the…read moreannual "Maintenance Agreement". Well, we are 100% satisfied with the quality of workmanship, professionalism, prompt service, friendly attitude and excellent products sold. We have never needed a service call on either machines to date. The annual maintenance is such an outstanding offer. It gives you peace of mind that your investment is being taken care of. I would love to recognize Ray Seeber, our technician for his outstanding quality of work. He was so informative, patient and respectful. Thank you Ray, we look forward to seeing you again. Kettle Moraine, you are certainly the BEST!!!! Mr.& Mrs. O'Brien

So pleased with the service I received from Damyon Selby at Kettle Morraine heating. He completed a…read moretune up on my furnace, was very knowledgeable and personable. He provided me with a description and cost of maintenance that will be needed in the future and I didn't feel like he was trying to sell me things I didn't need. I will absolutely request Damyon for our future furnace needs and will recommend him and Kettle Morraine heating to others.

I'm not big on writing reviews, but this service was exceptional…read more My heat went out last night during the Packer game. I called as soon as it was over thinking I'd have to leave a message for a call back in the morning. Nope. The owners wife was so friendly despite it being late on Sunday. They answered the phone, offered to come out that night, but opted for an appointment during regular hours. Are you ready for this? They got me in the next morning, diagnosed it right away, ran to get parts across town, and had them installed so fast it was spooky. I'm hesitant to trust heating and cooling companies, but was seriously impressed. They'll be coming back for a clean and check on my furnace and A/C unit this spring. Great job, Russ. Yep, the owner of the company is still in the field

Turned on the air yesterday so John could come home to a cool home after a day of construction…read morework. No cool air. John got home, called Russ as he had previously used him for AprilAire. Before 10 am today cold air is blowing! VERY nice, professional, reasonably priced, transparent in their work, open for any communication or questions during and after. I feel TOTALLY CONFIDENT giving this company 5 WELL-DESERVED stars!

First and last time calling them. The technician showed up 2 hours late and was not pleasant. I…read moreasked him how his day was going, and he said "It has been a long day" walked around the house to the AC unit and plugged in his freon gauge. In less than 5 min. of him being there, he told me I needed to replace my AC unit. He said the cost would be around $6800 and the price would be going up so I should buy it now. We walked to the basement, and he looked at the air filter (which I told him I cleaned prior) inspected it and said, "Yep you need a new AC unit" and then lectured me on the age of the unit. The technician walked outside and spent more time writing up the invoice then he did diagnosing my AC unit. In total, he spent 15 min. looking at my AC unit and 20 min. writing up the invoice. He told me the total was $240, I said that was ridiculous and he told me to call the office. I called the office and spoke with David before he left my driveway. David said he would need to talk to the boss. The next day he left me a voicemail saying they would not lower the price and that they could take some money off a new unit.

From the owner: - Air Conditioning - Heating Services…read more- Central Air - Gas Furnace Installation/Maintenance - Boiler Installation/Maintenance - Air Duct Cleaning - Air Duct Sealing - Unico System Installation - Preventative Maintenance

We had our old (43 years old!) furnace replaced. Sales person came on a Friday, told me our…read moreoptions, set us up with a credit company that put us on a payment plan, and scheduled the installation for Saturday-- the next day! No extra charge for work on a weekend! Salesman said the job would take 7 hours. It was done in less than 5. The installers were fast and friendly. 5 stars!

Very knowledgeable serviceman who answered all of our questions. Very professional yet with a…read morepersonal touch. Was truly interested in our specific concerns and questions. Did not take long to arrange an appointment. Offered suggestions on best way to set and regulate our furnace. After many years with another company that we've learned to distrust, a change was necessary and Donovan & Jorgensen definitely left us with a very good impression.

Tom misquoted work I hired him to do. He gave me a quote, showed up for the job, realized he didnt…read morepay enough attention (he overlooked my basement ceiling being drywalled ) He started the job but decided after cutting three vents holes in my floors that he didn't want to finish the job he misquoted. Than he sent Elizabeth his admin person to do his lying for him. They now demand i remove the entire ceiling and verify there is no mold or asbestos before they will return. We discussed the condition of the basement, specifically that there is soke mold and likely asbestos wrapped pipes. The morning he arrived to do the job he immediatelyadmitted he screwed up. He assured me he would do the work anyways as it was his mistake. Now he won't respond to messages sent directly to him, and Elisabeth is like dealing with a child who will not admit they are wrong. Despite the very good reviews, it has been a nightmare trying to get this company to follow through with what they said they would do. I strongly recommend you look elsewhere for your work.

Tom Yodor maintains the HVAC equipment in my home. He does a terrific job, and is very…read moreinformative so that I can plan work in the future. This past Monday he installed a new Honeywell T10 Lyric thermostat. He tied this in to my existing bypass humidifier to automatically control it to minimize window sweating in the summer. The new controls required a new wire to tie the thermostat to the humidifier. Tom efficiently ran the wire from the main floor to the basement. The T10 can also control via remote sensors to assure adequate heating and cooling. I am very happy with the thermostat, and how the system operates!

We called Pat's to diagnose and repair our boiler, which decided to crap out on us on a Sunday. The…read moretech, Michael quickly gave us a call back, and within an hour he arrived at our place. Michael not only diagnosed and repaired the boiler in record time, but he was also kind enough to take the time to thoroughly explain how a hydronic heater works, and all of the necessary maintenance involved. Michael was extremely knowledgeable with all things HVAC. We were charged a very fair price for the labor, especially considering the weekend callout. Fast forward a few weeks, and we called out Michael to update some of the heater controls. Again, Michael provided outstanding service and corrected a few other issues with our hydronic system. Still highly recommended!

Update 4-14-2026 To finalize this exchange and summarize…read morePat's treatment of my family and I. I have been extorted by Robert, accused of fluffing the bill, and essentially told that due to Pat's mistakes I am no longer welcome to use the service. This last part is verifiable in the response given to me. To whomever is above Robert I want to clarify how this situation was 100% caused by your company and now I am being painted to be the villain. If you pull the phone record you will hear that my family and I never once asked for a discount. In fact Robert was adamant he make it right and reactively (as this was after the first screw up) offered to take this job on the chin. I encourage you to ask Michael, as he is a super honest employee of the conversations we had with him as he made a mistake and misquoted. I assure you he will be nothing but truthful regardless if he made the blunder. With all this being said I am now not welcome to use your service according to the Google commentator. For that I am bummed as the workmanship, when Pat's does show up has been historically a class act. I have contacted the BBB, and Angie's list due to the extortion and treatment by Robert and Pat's heating as a whole. I do not care what the outcome is but to sit back and be bullied due to Pat's mistakes, and Robert's incompetence is absolutely ludacris. To the owner, if you want to make right terminate Robert's employment and I would be more then willing to continue business as my family has done so for the last 20 years. Robert has done nothing, and I mean nothing to make any of this experience pleasurable. Even eating the job, which your team did as Robert promised, came at the expense of extortion, and painting my family and I as the villain. I must say that the treatment of my wife and dying father (the one sitting home waiting for Pats delaying treatments to be available) lead me to get involved. The owner is welcome to call my dad and he will give you my number. I will not discuss anything with Robert as 99% of these issues came from his failed management. To any users reading this know I do this to show you the caliber of people Pat's employees. In the unfortunate event an issue does arise that is out of your control it is evident Robert will say whatever it takes to try fixing the solution but do minimal to help. A liar is a liar, beware before making any Deals with him and I will encourage anyone to get anything he says in writing to expedite the back and forth I had to do to get him to honor his commitment.

I worked with Droegkamp to have a heating unit added to my garage. They came out and discussed…read moreoptions for the unit, its placement and how best to run the utilities to it. Once the unit came in, the installation crew did a great job getting things up and running and cleaning up the work site. Really pleased with Droegkamp!

Company installed all my HVAC equipment when I built my home 5 years ago. Quality work, friendly…read morepeople. Also thorough routine service. Highly recommend.

I had the luck of my heating system crashing on Christmas, but luckily I was able to get hold of…read moreShane at On Time Heating & Cooling when no other HVAC companies were available. He was over super fast and quickly diagnosed the problem with my system. We went over a few options and all questions I had. I ended up upgrading to a new furnace and had it installed only a few days later. The install techs were prompt and courteous and did a great job. I now have a much improved air flow in the house and peace of mind knowing the new system will last a long time. I also purchased the maintenance plan which not only saved me money on the initial service call but will save me on future calls and includes my spring and fall tune-ups. I would definitely recommend On Time Heating & Cooling for your HVAC needs.

On Time Heating and Cooling is a great and on time. I've used them for my furnace, my…read moreair-conditioner and to install a new water heater. Everyone I've dealt with (Shane, Dion, Zachary and Travis) have all been very knowledgeable and know how to get the job done right. I would highly recommend them to anyone looking for a great HVAC company.