KMC Controls BAC-4000 series, Installation, Operation, And Application Manual

Page: 74 / 128

Staged heating and
cooling for for roof
top and heat pump
units
Staged heating and cooling is used for applications other than chilled or hot
water systems. Typically the AppStat controls gas heat, electric heat, or direct
expansion (DX) cooling with staged heating and cooling. Staged cooling or
heating can be mixed with a modulating valve for cooling or heating.
Staged cooling
As the demand for cooling increases, the AppStat starts the first stage of
cooling when the cooling PID loop rises above 95%
and the first stage of
cooling has been turned off for at least the time set by the value of
MINIMUM OFF TIME. The second stage of cooling is turned on when the
cooling loop rises above 99%
and the first stage has been turned on for the
period set by STAGE DELAY and the second stage has been turned off for at
least as long as the value of MINIMUM OFF TIME.
As the demand for cooling is satisfied, the second stage is turned off when
the cooling PID loop drops below 50%. This first stage is turned off when the
cooling loop drops below 5%.
Staged heating
As the demand for heating increases, the AppStat starts the first stage of
heating when the heating PID loop rises above 95%. The second stage of
heating is turned on when the heating loop rises above 99%
and
the first stage
has been turned on for period set by STAGE DELAY.
As the demand for heating is satisfied, the second stage is turned off when
the heating PID loop drops below 50%. This first stage is turned off when the
heating loop drops below 5%.
Fan control for roof
top and heat pump
units
A user with Password 1 can set the AppStat controlled fan to either run
continuously or to start automatically on a call for cooling or heating. See the
topic
Setting the operating modes on page 36 to set the fan configuration.
On —The fan will run continuously regardless of the heat/cool modes or
occupied/standby states.
Auto —When Off is selected, the fan runs only when there is a call for heating
or cooling. It continues to run for the period set by the fan delay timer after
the call for heating or cooling.
Section 5: Sequences of operation KMC Controls, Inc.
74 Revision G