Specifications

Piping
1. All units are recommended to be connected to supply and return piping in a two-pipe reverse return
configuration. A reverse return system is inherently self-balancing and requires only trim balancing
where multiple quantities of units with different flow and pressure drop characteristics are connected to
the same loop. A simple way to check for proper water balance is to take a differential temperature
reading across the water connections. To insure proper water flow, the differential should be 10°F (5℃)
to 14°F (8℃). A direct return system may also be made to word acceptably, but proper water flow
balancing is more difficult to achieve and maintain.
2. The piping can be steel, copper or PVC.
3. Supply and return run outs are usually connected to the unit by short lengths of high pressure flexible
hose which are sound attenuates for both unit operating noise and hydraulic pumping noise. One end of
the hose should have a swivel fitting to facilitate removal for service. Hard piping can also be brought
directly to the unit although it is not recommended since no vibration or noise attenuation can be
accomplished. The hard piping must have unions to facilitate unit removal. See FIGURE D for typical
piping setup.
4. Supply and return shutoff valves are required at each conditioner. The return valve is used for balancing
and should have a "memory stop" so that it can always be closed off but can only be reopened to the
proper position for the flow required.
5. No unit should be connected to the supply and return piping until the water system has been cleaned
and flushed completely. After the cleaning and flushing has taken place, the initial connection should
have all valves wide open in preparation for water system flushing.
6. Condensate piping can be steel, copper or PVC. Each unit is supplied with a 3/4" (19.05mm) ODM
copper stub.
7. The condensate disposal piping must have a trap and the piping must be pitched away from the unit not
less than 1/4" inch per foot (20mm per meter). Generally, the condensate trap is made of copper. See
FIGURE E. A piece of vinyl hoses from the trap to the drain line is used for simple removal. A complete
copper or PVC condensate system can also be used. Union fittings in the copper lines should be
applied to facilitate removal.
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