The foundation can be made from cement, crushed rock or patio bricks.
The water supply and return lines must be installed so that they are
protected against damage and against sunlight, freezing and fire.

The cutout at back of the foundation is to accomodate the supply and return lines
so that they can enter into the back of the heater from beneath the foundation.

The heater bottom panel has knockouts in place for this purpose.

** Note build pad at least 1 foot larger as this is the actual boiler footprint! **