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NOTE: Care is needed not to set the Lag Panel Start
Point % too high. If this occurs, the lead group
of compressors will attempt to overchill the liq-
uid flowing through their evaporator below the
Low Limit Water Temperature (See Section 6)
to compensate for the unchilled flow through
the other evaporator. The mixed chilled liquid
temperature will remain above the Control
Range until the lag group of compressors start.
NOTE: Situations may occur in low ambient conditions,
when control is based on %FLA, where current
drawn at full load (100% slide valve) will be quite
low. The actual operating current for a fully
loaded compressor may be as low as 65 - 85%
of the motor FLA at ambients below 95°F. If,
due to system conditions, the lead compressor
does not reach the programmed %, even
though the lead system is fully loaded, the lag
compressor will start regardless of the pro-
grammed % after 5 minutes of operation when-
ever the lead compressor can not bring the LWT
to within 2.0°F of the high end of the Control
Range (CR). Once the lag compressor is
started, equalized loading and unloading of the
two compressors will occur. This assures that
the chiller will fully load and maintain chilled liq-
uid temperature.
NOTE: Situations may occur in low ambient conditions
when control is based on %FLA, where current
drawn at full load (100% slide valve) will be quite
low. The actual operating current for a fully
loaded compressor may be as low as 65 - 85%
of the motor FLA at ambients below 95°F. If due
to the system conditions the lead compressor
group does not reach the programmed % even
though the lead group is fully loaded, the lag
group will start regardless of the programmed
% after 10 minutes of operation whenever the
lead group can not bring the LWT below the
high end of the Control Range (CR). Once the
lag group started, equalizing loading and un-
loading of the two groups will occur. This as-
sures that the chiller will fully load and maintain
chilled liquid temperature.
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