Some heaters manufactured or revamped by Tulsa Heaters, Inc. can have their thermal efficiencies improved to 90 - 92% by the addition of an Air Preheat System, creating significant fuel cost savings, especially on large-duty heaters. There are also cases where a natural draft heater is stack-limited or approaching its permited maximum heat release, and adding an air preheat system can increase heater throughput.

THI's engineers provide their innovative design expertise to give clients' APH systems superior performance features:

• Duct sizing for proper gas velocities.
• Duct, fan and exchanger layout to optimize plot space utilization.
• Appropriate ancilliary equipment, including control dampers, expansion joints, guillotine blinds, by-pass ducts and emergency air doors.
• Proper instrumentation to interface with heater controls and safeties.