The water heater is connected to the gas furnace ... To replace it, they would need to bring the vent that connects it to the furnace, which is done through another vent ... so that other vent would also need to be brought up to code ... and any other vent that is part of that chain ... resulting in many, many feets of B-vents. Direct Energy would not charge for the new tank ('cause it is a rental) but they would charge labor and parts for upgrading all the vents. And since it is apparently code to have B-vents (a new thing I believe), they cannot proceed without doing that work first. I'm trying to find info to determine whether or not it's true the new code regulation is in effect and therefore the vents must be changed. If the vents do not need to be brought up to code, then I can have the water tank replaced at no cost to me!