57
YORK INTERNATIONAL
FORM 100.50-NOM1 (604)
5
TABLE 16 – CV (CONSTANT VOLUME) MODES OF OPERATION
Control
Heating
Cooling
Occupied
Unoccupied
Occupied
Unoccupied
Thermostat
Controller Occupied input is
ON (energized by ‘stat occ.
output, or by an external
com mand). ‘stat uses its
programmed occupied htg.
Setpoint. Supply fan con-
trolled by ‘stat’s G output.
Economizer damper at
programmed min. position.
‘stat W1, W2 outputs control
heating stages 1and 2.
If hydronic heat or modulat-
ing gas heat, ‘stat W1,W2
outputs select programmed
“Hydro heat 1
st
and 2
nd
stage Setpoints
Controller Occupied input
is OFF (deenergized by
‘stat occ. output, or by an
external command).
Economizer damper is at
0% Control is same as oc-
cupied heating, except ‘stat
uses its programmed unoc-
cupied heating setpoint.
Controller Occupied input is
ON (energized by ‘stat occ.
output, or by an external
command). ‘stat uses its
programmed occupied clg.
setpoint.
Supply fan con-
trolled by ‘stat’s G output
Economizer damper at
programmed min. position,
may modulate open if free
cooling is being used.
Mechanical cooling mode:
‘stat Y1, Y2 outputs control
stage 1 and 2 compressors
Economizer mode:
‘stat Y1, Y2 outputs select
High and Low programmed
Economizer SAT setpoints,
SAT controlled by econo-
mizer control algorithm.
Controller Occupied input
is OFF (deenergized by
‘stat occ. output, or by an
ex ter nal command).
Economizer damper is at
0% (damper may modulate
open if free cooling is being
used). Control is same as
occupied cooling, except
‘stat uses its pro grammed
unoccupied cooling set-
point.
Space Sensor
Controller Occupied input
is ON (energized by an
external command). Space
temperature is controlled
to a programmed oc-
cupied htg. setpoint. For
supply fan, setting of the
parameter “Fan ON mode
with the Sensor Option”
determines if the supply
fan is ON continuously,
or is in “Auto” mode (i.e.
goes off when space is
satisfi ed). Economizer
damper at programmed
min. position Heating is
controlled by a PI algorithm
that controls staging of heat
stages and modulates
duty cycle of the highest
numbered running heating
stage. If hydronic heat or
modulating gas heat, space
control algorithm selects
programmed “Hydro Heat
1
st
Stage SAT Setpoint” and
“Hydronic Heat 2
nd
Stage
SAT Setpoint”
Controller Oc cu pied input
is OFF (deenergized by
an external command).
Economizer damper is at
0% Supply fan is in “Auto”
mode (i.e. goes off when
space is satisfi ed). Control
is same as occupied heat-
ing, except space tem-
perature is controlled to a
programmed unoccupied
heating setpoint.
Controller Occupied input
is ON (energized by an
external command). Space
temperature is controlled
to a programmed occupied
clg. setpoint.
For supply fan, setting of
the parameter “Fan ON
mode with the Sensor
Option” determines if the
supply fan is ON continu-
ously, or is in “Auto” mode
(i.e. goes off when space is
satisfi ed).
Economizer damper at
programmed min. position,
may modulate open if free
cooling is being used.
Mechanical cooling mode:
Cooling is controlled by a
PI algorithm that controls
compressor staging and
modulates duty cycle of the
highest num bered running
compressor.
Economizer mode:
Space control algorithm
selects High and Low pro-
grammed Economizer SAT
setpoints, SAT controlled
by economizer control
algorithm.
Controller Occupied input
is OFF (deenergized by an
external command).
Economizer damper is at
0% (damper may modulate
open if free cooling is being
used).
Supply fan is in “Auto”
mode (i.e. goes off when
space is satisfi ed).
Control is same as oc-
cupied cooling with a space
sensor, except space
temperature is con trolled to
a programmed unoccupied
clg. setpoint.