70 RTHD-SVX01D-EN
Installation Electrical
fully reset immediately (within one minute). The chiller will then start at the
Differential to Start value above a fully reset CWS or CWS' for Outdoor,
Return, and Constant Return Reset.
Equations for calculating CWR
Equation used to get Degrees of Reset:
Outdoor Air:
Degrees of Reset = Reset Ratio * (Start Reset - TOD)
Return Reset:
Degrees of Reset = Reset Ratio * (Start Reset - (TWE - TWL))
Constant Return:
Degrees of Reset = 100% * (Design Delta Temp - (TWE - TWL))
To obtain Active CWS from Degrees of Reset:
Active CWS = Degrees of Reset + Previous CWS
Note: Previous CWS can either be Front Panel, BAS, or External
Reset Ratio calculation:
The Reset Ratio on the User Interface is displayed as a percentage. To use it
in the above equation it must be converted to its decimal form.
Reset Ratio percent / 100 = Reset Ratio decimal
Example of converting Reset Ratio:
If the Reset Ratio displayed on the User Interface is 50%
then use (50/100) = .5 in the equation
TOD = Outdoor Air Temp
TWE = Evap Entering Water Temp
TWL = Evap Leaving Water Temp
Programmable Relays (Alarm and Status) - Optional
CH530 provides a flexible alarm or chiller status indication to a remote loca-
tion through a hard wired interface to a dry contact closure. Four relays are
available for this function, and they are provided (generally with a Quad Relay
Output LLID) as part of the Alarm Relay Output Option.
The events/states that can be assigned to the programmable relays are listed
in the following table.
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