CEMP-E
TI 811-12
18 August 1998
considerable damage. The chiller manufacturer's recommended minimum cooling capacity and
temperature limits will be incorporated into the sequence of operation shown. In general, surges occur in
chillers at loads below 20% of the rated capacity. Design requirements for this applications program will
be indicated by the letter X adjacent to the demand limiting step listing on the appropriate database table,
as shown in Chapters 8 and 9.
a. Field hardware requirements. The hardware requirements are:
(1)
UMCS inputs from utility system. Chiller current - 1 per chiller.
(2)
UMCS outputs to utility system.
(a)
Step control signal - one per step per chiller.
(b)
Or, analog control signal - one per chiller depending on chiller control interface.
b. Software I/O requirements. The software requirements are:
(1)
Program inputs.
(a)
Chiller percent capacity.
(b)
Minimum cooling capacity.
(c)
Equipment priority schedules.
(d)
Equipment constraints.
(2)
Program output.
(a)
Calculated percent load point
c.
Application notes. This program is used in conjunction with the demand limiting program.
14. DAY/NIGHT SETBACK PROGRAM. The energy required for heating or cooling during unoccupied
hours is reduced by lowering the heating space temperature setpoint or raising the cooling space
temperature setpoint. This applies only to facilities that do not operate 24 hours a day. Space
temperature can be reduced from the normal winter inside design temperature to a lower space
temperature during the unoccupied hours. In spaces that require air conditioning during unoccupied
hours, the normal temperature setting is reset upwards to a temperature that is compatible with space
requirements. Design requirements for this applications program will be indicated by listing of default
occupied and unoccupied cooling and heating space temperature setpoints on the appropriate database
table, as shown in Chapters 8 and 9.
a. Field hardware requirements. The hardware requirements are :
(1)
UMCS inputs from utility system.
(a) Equipment status (differential pressure switch, auxiliary contact, flow switch) - one for
each HVAC systems.
(b)
Space dry bulb temperature (minimum of one per zone )
(2)
UMCS outputs to utility system.
(a) Day/night control signal to interposing relays (momentary or maintained signal as
required by the equipment control circuit and failure mode) - one for each HVAC system.
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