I had a problem with my gas heat- no heat or flow in one zone of the house. I called Wolff for service. I do have an old two zone heating/AC system with the heater in the attic. The tech promptly came, and went up in the attic and said the limit switches are weak and he has adjusted them, and it will work. He said it takes an hour or more for me to feel the heat. He recommended a new system, and gave me a detailed quote for a new system, strongly pushing it. He also charged me $160 for the service call. After he left, there was no heat even after a few hours. I reluctantly went up on the attic myself to check, and found that the duct system that connects to the heater was completely disconnected and the duct was lying on the floor, with nice hot air spewing into the attic. I reconnected it and secured it with duct tape, and lo and behold, got heat in the house immediately. I am unhappy that I was charged $160, though the problem was obvious and unattended to; the tech was only interested in trying to sign me up for a new system. I needed to replace my old system, but chose another company based on this experience. I hope this was an an isolated problem since i do see good reviews from others.