We are installing a gas hot water tank, venting is going through the roof, could you please give us a diagram to follow to install. Thanks. The roof is flat, it is an addition to home so it doesn't have much of an attic. About a foot or so.

The install manual that came with the water heater should explain a lot better than we can.

We do not have instructions from our hot water manual as to how to install ducting for hot water tank

Is this just a standered water heater or a power vented one?

It is a standard gas, GE 50 gal.

You will just need 4 in b vent double wall, and take it up threw the roof 18 inches above the roof line. You will need a cap, a storm colar, and a roof boot.