Genesis is designed to provide users with any high temperature thermal medium at the desired operating pressure to enhance their operations. The high temperature fluid generators heat any suitable thermal oil, glycol-water mixture or water, with output capabilities ranging from 5 million to 200 million BTU/hr. A membraned wall furnace provides gas-tight construction that offers structural integrity while minimizing refractory. Opposed corner headers allow for equal tube lengths and even thermal expansion. This unit replaces older tangent-wall technology that previously required manually adjustable orifices to distribute flow.