59
YORK INTERNATIONAL
FORM 100.50-NOM1 (604)
5
Occupied Heating With A Space Sensor
• The programmable parameter
"VAV with Thermo-
stat"
is OFF, and a space sen sor is available and the
"Space Sensor Enable"
parameter is ON.
• The programmable parameter enable setting
"Oc-
cupied Heat ing"
must be set to ON to enable the
Occupied Heating With A Space Sensor function.
• The stepped heating control algorithm is:
◦
Turned ON when the space temperature is less
than the “VAV Sp for SAT Reset” by 20F
◦
Monitors the return air temperature and controls
the unit between the “
Warm-Up RAT
” and the
“
Warm-Up RAT
” minus 2 F.
◦
Turned OFF when the space tem per a ture is great er
than (
"VAV SP for SAT Reset"
- 1.5°F) or the RAT
reaches setpoint.
◦
Figure 30 illustrates the algorithm for oc cu pied
heat ing required.
• For hydronic heating:
◦
The SAT is controlled to the 2
nd
Stage Hy dron ic
Heat Setpoint.
◦
The Heat 1 output of the controller is set to con trol
HIGH during heating.
Unoccupied Heating With A Space Sensor
• The programmable parameter "
VAV Operation with
Thermostat"
must be set to OFF and Space Sen sor
signal must be reliable.
• The programmable parameter
"VAV Occupied Heat-
ing"
must be set to ON to enable the Oc cu pied Heat-
ing With A Space Sensor function.
• For hydronic heating:
◦
The SAT is controlled to the 2
nd
Stage Hy dron ic
Heat Setpoint.
◦
The Heat 1 output of the controller is set to con trol
HIGH during heating.
Occupied Cooling With A Space Sensor
• The programmable parameter
VAV Op er a tion with
Thermostat
must be set to OFF and Space Sen sor
sig nal must be reliable.
• The SAT setpoint for cooling is the
"VAV Cool Low
Temp"
or
"VAV Cool High Tem p"
through compari-
son of the space tem per a ture and the
"VAV SP for
SAT Reset"
as shown in Fig ure 30.
Unoccupied Cooling With A Space Sen sor
• The programmable parameter
VAV Op er a tion with
Thermostat
must be set to OFF and Space Sen sor
sig nal must be reliable.
• Cooling is called for ac cord ing to the al go rithm
il lus trat ed in Figure 28.
◦
The SAT setpoint for unoccupied cool ing is the
VAV Cool High Temperature Setpoint.
• Both the space temperature and the RAT must be
2°F below their setpoints.
• The space temperature is controlled to the Un oc -
cu pied Heating Setpoint using the algorithm il lus -
trat ed in Figure 27.
5
FIG. 26 –
VAV OCCUPIED HEATING TO MAINTAIN
RAT AND MORNING WARM UP
LD06557
All heating steps
sequentially added
All heating steps
dropped
MWU Setpoint
RETURN AIR TEMPERATURE (˚F)
-2.0
ON
OFF
FIG. 27 –
VAV UNOCCUPIED STEPPED HEATING-
TEMPERATURE CONTROL
LD06558
All heating steps
dropped
SPACE TEMPERATURE (˚F)
-0.5˚F
+0.5˚F
UNOCC. HTG. SETPOINT
All heating steps
sequentially added
ON
OFF