Figure 62 - Constant Volume Setpoint Determination - Johnson Controls LSWU Manual

FORM 145.05-NOM7
ISSUE DATE: 10/31/2019
A COMM ZONE TEMP (Communicated)
connection to the unit keeps the last tem-
perature input from the Building Automa-
tion System (BAS) if the communications
is interrupted.
OCC HEATING HIGH
ZONE TEMP IS MORE
THAN 1.5 °F BELOW THE
ZONE TEMP SP
OCC HEATING LOW
ZONE TEMP IS
SUPPLY FAN AT 100%
BETWEEN .5 °F AND
1.5 °F BELOW ZONE
TEMP SP
SUPPLY FAN AT 100%
H
E
A
T
I
N
G
H
I
G
H
NOTES:
1- WHENEVER THE UNIT ENTERS AN ACTIVE COOLING OR HEATING MODE, THE UNIT CONTROLLER WILL UTILIZE AS MANY OR AS FEW STAGES OF COOLING or HEATING
THAT IT NEEDS TO ACHIEVE AND MAINTAIN THE ACTIVE SUPPLY AIR TEMP SP.
2- UNOCCUPIED SEQUENCE WILL BE THE SAME AS ABOVE EXCEPT THE ZONE TEMP SPs USED WILL BE THE UNOCC SP's VALUES.
3- UNIT MODES WILL STAGE DOWN WHEN THE ZONE TEMP IS .5 °F UNDER SPs FOR COOLING AND .5 °F OVER SPs FOR HEATING.

FIGURE 62 - CONSTANT VOLUME SETPOINT DETERMINATION

Constant Volume
A Constant Volume unit with the Zone Control Method
does not have a direct effect on the control of the com-
pressor and heating stages. Instead the Zone (hardwired
or communicated) input is only used to determine the
UNIT MODE. The staging of the compressors and fac-
tory optioned heat source is always based on the "SUP-
PLY AIR TEMP ACTIVE SP."
JOHNSON CONTROLS
Z
O
OCC STANDBY
OCC STANDBY
N
ZONE TEMP IS
ZONE TEMP IS
E LESS THAN .5 °F
LESS THAN .5 °F
ABOVE ZONE
BELOW ZONE
TEMP SP
TEMP SP
S
H
SUPPLY FAN AT
SUPPLY FAN AT
E
E
100%
100%
A
T
T
P
I
O
N
I
G
N
L T
O
W
Zone Temperature Control
When the "CONTROL METHOD" is set to Zone Tem-
perature Control (either hardwired or communicated),
the "SUPPLY AIR TEMP ACTIVE SP" is determined
by the difference between the ZONE TEMP and the ap-
propriate zone setpoint. Table 19 on page 102 shows
the parameters that are used to determine the "SUPPLY
AIR TEMP ACTIVE SP."
Where: ΔTOC = "ZONE TEMP" – "OCC ZONE
COOLING SETPOINT," ΔTOH = "ZONE TEMP"
– "OCC ZONE HEATING SETPOINT," ΔTUC
= "ZONE TEMP" – "UNOCC ZONE COOLING
SETPOINT," and ΔTUH = "ZONE TEMP" – "UNOCC
ZONE HEATING SETPOINT"
SECTION 5 – SEQUENCE OF OPERATION
OCC COOLING HIGH
ZONE TEMP IS MORE THAN
1.5 °F ABOVE THE ZONE
TEMP SP
OCC COOLING LOW
ZONE TEMP IS
SUPPLY FAN AT 100%
BETWEEN .5 °F AND
1.5 °F ABOVE THE
ZONE TEMP SP
SUPPLY FAN AT 100%
C
O
O
C
L
O
I
O
N
L
G
I
N
H
G
I
G
L
H
O
W
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