Table of Contents
Advertisement
Sequence of Operations
before Lead is rotated. Demand Rotation rotates Lead
when the last compressor is staged off.
7. Primary Controller constantly monitors the Controlled
Temperature and checks if it falls within Temperature
Control Band. Temperature Control Band is the zone
around Temperature Setpoint where Cooling/Heating
Demand is modulating. When Load Water Controlled
Temperature is below Control Band for Cooling Mode,
Cooling Demand is 0%; when Load Water Controlled
Temperature is above Control Band, Cooling Demand
is 100%; when Load Water Controlled Temperature is
changing within Temperature Control Band, Cooling
Demand is modulating accordingly. The same goes for
Heating Demand except for when Load Water
Temperature is below Control Band, Heating Demand
is 100% and when it is above Control Band, Heating
Demand is 0% as heating temperature control is
reversed versus cooling temperature control.
8. Compressors staging sequence always starts off from a
Lead Module. When Bank Demand is 100%,
compressors stage up; when Bank Demand is 0%,
compressors stage down. Once next compressor
comes on, Stage-up Delay has to expire before next
compressor is allowed to turn on. The same goes for
58
staging-down, Stage-Down Delay has to count down to
'0' before next compressor turns off.
a. When next Heat Pump Module comes into
operation, it first opens its Load and Source
Isolation Valves. While Isolation Valves are
opening, pumps ramp up to readdress
increased flow demands. When Load Flow is
confirmed by a flow switch, compressors are
allowed to start.
b. In Heating Mode Source Flow has to be
confirmed before starting compressors.
Running chilled water, Water Source Heat
Exchanger operation in Heating Mode is more
critical as opposed to Cooling Mode as it may
be subject to potential freezing.
c. When Bank Demand reaches 0%, WXM Bank
goes into staging-down sequence. Staging-
down always starts from the compressor that
was engaged last implementing LIFO sequence
(Last In First Out).
d. When the last compressor on the Heat Pump
Module stops, Isolation Valves start closing.
Pumps in corresponding circuits ramp down to
adjust speed to decreased flow demands.
ARTC-SVX010A-EN
Advertisement
Table of Contents
