Room air is drawn through the return air grille and through the lower half of the riser heat-exchanger into the blower. It then blows through the upper half of the riser heat-exchanger from the double-tapered plenum on the blower discharge, after which the conditioned air returns to the room through the supply grille(s).

The two air passes through the finned coil surfaces are equivalent to a "four-row" heating/cooling coil.

Advantages For The Buiding Owner
• Elimination of brazed joints within the unit.
• Lower maintenance (filter change only): No valves, permanently lubricated motor
• Floor level maintenance: No ladders required.
• Lower pumping costs: Elimination of system resistance caused by valves trains, coils and runout piping.
• Aesthetics: Drywall enclosure
• Aluminum Grilles - No unsightly steel panels or access openings. All service can be performed through the grille openings.
• Quiet Operation Advantages For The Contractor
• Labor savings
• Complete piping package included.
• Risers are provided and factory installed in each unit.
• No need for labor and material for runout piping from the unit to the supply/return riser.
• No venting of individual units.
• No balancing of individual units.
• Plug-in thermostat - Surfaced mounted
• Job site distribution simplified due to precise identification and labeling of each unit.Sequence of Operation

Two-Pipe Fan Cycle Control
The standard two-pipe unit uses continuous water circulation through the riser heat-exchanger. The building owner provides chilled water in the summer and warm water in the winter. The thermostat cycles the fan on and off to maintain the thermostat temperature setting. Summer/winter changeover of the thermostat action is automatic, and the user has manual fan speed selection of HI, LO, or OFF.

Two-Pipe Face and Bypass Damper Control
The two-pipe face and bypass unit uses continuous water circulation through the riser heat-exchanger in the same manner as the two-pipe fan cycle control unit. Fan operation is continuous. The thermostat cycles an internal face and bypass damper which either directs the air over the riser heat-exchanger when cooling or heating is required, or allows the air to bypass the riser heat-exchanger completely. The fan recirculates room air when neither heating nor cooling is required. Summer/winter changeover of the thermostat action is automatic, and the user has manual fan speed selection of HI, LO, or OFF.