Other unit heaters available today are designed with the old clamshell style heat exchanger, positioned above ribbon-style burners. These are the most common points of failure, especially in the greenhouse environment. Heat exchangers invariably fail at the points where manufacturing processes have weakened the metal by stamping, crimping and welding. Modine HD gas heaters are equipped with a tubular heat exchanger which consists of smooth, continuous tubes are formed in a serpentine shape and then placed in parallel rows. This type of heat exchanger has no stress points, no points where the metal has been compromised making it more durable than a similar clamshell heat exchanger and allowing the unit to be equipped with in-shot burners.

Modine Advanced Burner Design Modine HD's burner design is more akin to that of a fire-tube boiler than a unit heater. With these in-shot burners, the flame is retained inside the heat exchanger and fires down the inside of the heat exchanger tube. This design accomplishes three things: First, it eliminates the need for separate conventional ribbon-style burners; Second, it enhances flame quality and heat transfer; and Third, it eliminates most burner corrosion problems. Conventional burners fail when moisture from condensation drips on them. This problem is eliminated with the Modine in-shot burner system.