Deadband
This is the to lerance on the chilled water/ brine temperatu re
CONTROL POINT
. If the water
temperature goes out s ide of the
DEADBAND
, the PIC opens or closes t he guide vanes in
response until it is within t olerance. The P IC may be co nfigured with a 0.5 to 2 F (0 .3 to 1.1 C)
deadband.
DEADBAND
may be viewed or modifie d on t he Equipment Service1 table.
For example, a 1° F (0.6° C) deadba nd setting controls the wat er temperature within ±0.5° F
(0.3° C) of the control point . This may cause frequent gui de vane movement if the chille d water
load fluctuates frequ ently. A value of 1° F (0.6° C) is th e default setting.
Proportional Bands and Gain
Proportional band is th e rate at which the guide vane position is corrected in proportion to
how far the chilled water / brine temperature is f rom the control point. P r opo rtional gain
determines how quic k ly th e gui de vanes react to how quic k ly t he temperature is movi ng from
CONTROL POINT.
The proportional band c an be viewed/modified on th e LID. There are two respons e modes,
one for temperature resp onse above the control po int, the other for respon se below the control
point.
The first type is called
PROPORTIONAL INC BAND
, and it can slow or quicken v an e
response to chilled wat er/brine temperatu r e abo ve
DEADBAND
. It can be adjusted from a
setting of 2 to 10; the defaul t setting is 6.5.
PROPORTIONAL DEC BAND
can slow or quicken