This thankless water heater Drain pan should be used whenever a thankless water heater is mounted in an area where a leak from the unit, or its connections, could cause water damage to finished surfaces. It can be mounted directly to the wall and the thankless unit can be plumbed through or around the pan. This pan is also convenient when flushing the unit during routine maintenance, as the water can be flushed right into the pan. As with any standard round Drain pan, this thankless pan should be plumbed, using the included fitting, to Drain any water leakage out and away from finished surfaces.