Looking for info on building an oil fired arch. Not much info on line. Been looking for pictures of major manufactures designs but pictures only show outside of arch. Am thinking arch should not have up-slope going back. Am also thinking flame should be as long as practical. Evaporator is a 2x8 raised flue, have a Carlin 201 CRD 2.5-5.5 gph burner. Have read that efficiency increases when burner fires forward. Any input would be greatly appreciated.