We are thinking about installing a new AO Smith power vent water heater tank, GPVL-50 with a 24-inch diameter. Would a 26-inch diameter drain pan be sufficient to accommodate for the discharge or drain pipe from the T&P valve, the air inlet snorkel at the back and also access to the bottom of the tank if it is ever necessary? Is there a need to access anything at the bottom of the tank that could potentially be obstructed by the wall of the drain pan if it is too small? Would a 28-inch drain pan be better choice or is that an overkill?

With our existing AO Smith tank (20-inch diameter) and drain pan (don’t know the size of it), it was nice to have enough room to access the air intake screen that was located at the bottom of the tank. Not sure if there is any need to access anything at the bottom of the tank with the new tank. Also, I assume an aluminuim drain pan is a better choice over a rubberized/plastic drain pan? Any advice? Thank you.

If you have room for the larger drain pan I would install it. A higher lip on a larger pan would be best. IMHO

yes, the drain at the bottom of the tank needs to be clear of the pan side wall so that a hose can be hooked up when needed. If you have the space the larger pan is better. The T & P drain should terminate with a 1" air gap above the rim of the pan.

that drain pan is realy just a drip pan. if that t& p blows theres no way it will hold full blast.best to run it through an outside wall and stop 6in. above the ground.the pan shows you when you have a small leak or a leak in the tank body,like an early warning system...good luck...dan

The drain valve can be rotated sideways to clear the edge of the pan, and NEVER depend on a drain pan to protect you from a T&P valve discharge flooding.