System Water Volume; Low Condenser Water Temperature Operation (Needs To Be Updated) - Daikin WCT Installation, Operation And Maintenance Manual

Nameplates
There are several identification nameplates on the chiller:

The unit nameplate is located on the side of the Unit Control Panel. It has a Style No. XXXX,
Model No. XXXX and Serial No. XXXX. These numbers are unique to the unit and should be used
to identify the unit for service, parts, or warranty questions. This plate also lists the unit operating
refrigerant charge.

Vessel nameplates are located on the evaporator, economizer and condenser. Along with other
information, they have a National Board Number (NB) and a vessel serial number, either of which
identify the vessel (but not the entire unit).

A compressor nameplate is located on the compressor itself and contains identification numbers.

System Water Volume

All chilled water systems need adequate time to recognize a load change, respond to that load change
and stabilize, without undesirable short cycling of the compressors or loss of temperature control. In air
conditioning systems, the potential for short cycling usually exists when the building load falls below
the minimum chiller plant capacity or on close-coupled systems with very small water volumes or due to
improperly operating system controls.
Some of the things the designer should consider when looking at water volume are the minimum cooling
load, the minimum chiller plant capacity during the low load period and the desired cycle time for the
compressors.
Assuming that there are no sudden load changes and that the chiller plant has reasonable turndown, a
rule of thumb of "gallons of water volume equal to two to three times the chilled water gpm flow rate" is
often used.
A properly designed storage tank should be added if the system components do not provide sufficient
water volume.

Low Condenser Water Temperature Operation (Needs to be updated)

When the ambient wet bulb temperature is lower than design, the condenser water temperature can be
allowed to fall. The resultant lower condensing temperature will improve chiller performance.
WCT chillers are equipped with electronic expansion valves (EEV) and will operate with entering
condenser water temperatures as low as calculated by the following equation and shown in the chart
following.
Note: Provisions or modifications need to be made in the event of inverted starts (condenser water
colder than chilled water). For example, 3 way bypass valve controlled by the chiller, or tower controls.
Min. ECWT = 10.973 + LCHWT – 0.17 * CHWDT

ECWT = Entering condenser water temperature

LCHWT = Leaving chilled water temperature

CHWDT

PLD = The percent chiller load point to be checked
= Chilled Water Delta-T at full load
FL
(PLD/100) + 8 * (PLD/100)2
FL
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