Disappointed with the guaranteed installation -- be careful! I got three quotes and went with Dupont to get a more efficient furnace and replace a rented hot water tank with a purchased one. The salesperson Rod, was extremely helpful, and there was no problem with the installation. BUT, a month or so later, a friend who is a licensed inspector came by the house and noticed the venting outlet in the walkway was too low. He said that raising it to the proper height would be straightforward. I called and emailed multiple times to ask them to extend the vent, based on the Inspector's comment and the fact that at the current height it blows unpleasantly people's faces. I had trouble getting in touch, was told people were on vacation, calls weren't returned, was asked for more detail by email which I provided... and it's still not fixed.