This information is not easily available , hence to make it more easily accessible I have also put it on Wikipedia under Yajna .
The sacred fire of a man is lit from his fathers fire at the time of his wedding .
It is then divided into two fires by a ritual called the Agniyadhana .
The two fires thus obtained are called the Gruhyagni (or Aupasanagni ) and the Srautagni.
They are to be preserved throughout ones life .
The Srautagni is further divided into three fires called the Garhapatya , the Ahavaniya and the Dakshinagni , collectively called the tretagni.
The Gruhyagni and the Garhapatya fires are kept alive continously , fire is taken from the Garhapatya (one of the tretagni's ) to kindle the remaining two as and when necessary .
The four fires are located as follows .
The Ahavaniya ( square in shape ) to the east , the Dakshinagni ( semi circular in shape) to the south , the Garhapatya ( circular in shape ) to the West, and the Aupasanagni ( may be circular or square ) to the north .