Direct Expansion Coil - Type DX

Primary Surface

Round seamless copper tubes are mechanically expanded into the fin collars of the secondary surface. The mechanical expansion provides a permanent metal-to-metal bond for efficient heat transfer. Tubes are staggered in the direction of airflow and only RETURN BENDS are used to ensure NO reduction in tube wall thickness in the bend radius associated with hairpin tubes.

Secondary Surface

Corrugated aluminum or copper plate-type fin that is die-formed. Fin collars are full-drawn to provide accurate control of fin spacing and maximum contact with tubes.


Seamless copper with die-formed holes that provide a parallel surface to the coil tube for strong brazing joints.


Interchangeable nozzle-type refrigerant distributors are brass and suction connections are copper sweat. Standard coil has one distributor for one compressor circuit. An INTERTWINED coil has two distributors that provide full face control using two compressor circuits. A FACE SPLIT coil has two or more distributors for multiple compressor circuits.


Die-formed flanges with stacking flanges on top and bottom. Intermediate tube supports are supplied on coils over 44” fin length with an additional support every 42”.


Coil circuiting options include full face (std.), intertwined, horizontal (face) split, and face split / intertwined.

Testing and Performance

All coil assemblies are leak tested under water with nitrogen at 315 PSIG.