I had new central air installed in my home about 9 yrs ago and a new furnace 5 yrs ago by Zenner and Ritter and I’ve used them exclusively for routine maintenance. This is a very professional company. They go over and above the standard. Last year I had a problem with my air conditioning and Greg found the problem in about 10 minutes. He came again this year for the routine maintenance and he remembered us. Greg is professional, knowledgeable and personable. He makes sure you understand what he is doing and why. I highly recommend Zenner and Ritter and Greg as well.