We have a 10+ year old gas water heater that has no pan under it. The water heater is just off the garage in a laundry/ furnace room. The heater sits on the floor and the house is built on slab. There is about 17" clearance between the exterior wall and the tank.
I was thinking I might remove this tank (on borrowed time now) and using large pavers or a wood structure raise a pan off the floor just high enough so that the drain pipe could run out of the wall just above the sill plate. I am not sure what angle I should use so it drains well enough. 3 feet to the left is the fresh air vent for the furnace so I really don't see a need to put in a "U" joint long as I cover the end of the pipe with a hinged cap or a piece of 1cm/ 1cm wire mesh to keep out the rodents etc.
Any thoughts?