Acson international AWH028C, Technical Manual

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Duct & Attenuation
1. Discharge ductwork is normally used with these conditioners. Return air ductwork may also be required, but will
require field installation of a 1" or 2" return air duct collar/ filter rack kit.
2. Return air duct should be internally lined with acoustic insulation for sound attenuation.
3. Don't use sheet metal screws directly into the unit cabinet for connection of supply or return air ductwork, especially
on return air ductwork which can damage the drain pan or the coil & tube.
Piping Work
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
2. 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 5
℃
to 6
℃
.
3. A direct return system may also be made to word acceptably, but proper water flow balancing is more difficult to
achieve and maintain
4. The piping can be steel, copper or PVC.
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.