What makes you think that, out of curiosity? I have talked to the guys at Hallmark Campers, who are local to me, and they had no issues at all getting set up with Truma and are installing them in most of their campers now. I know Truma does not sell direct to the public, which is where you come in I see (awesome, by the way!), but I highly doubt that Four Wheel would have any issues with it. The furnace they include now is ancient, a huge power hog, and LOUD. It also does not produce hot water or have the ability to run on AC power, both issues which the Truma Combi would solve. Instead, a secondary old school water heater tank has to be installed, which takes up more space as well. I realize the Truma is expensive, but given the issues it solves, I can't for the life of me figure out why Four Wheel hasn't offered it at least as an option by now. They've been going through so many changes over there with the new ownership and new manufacturing systems, incorporating something like this seems like a slam dunk.I believe Stan's issue is sourcing the actual Truma unit, not the install itself. I am sure he would be happy to install a Truma unit sources from us, link in my signature. Thanks.