York ECO2 YPAL 050 - Manual (Page 68)

68 JOHNSON CONTROLS
FORM 100.50-NOM6 (1207)
Sequence of Operation
The Simplicity Control will stage off the heat as
follows:
•
When the return air temperature is 2.4° F below
the “CV OCCUPIED HEATING” or “CV UN-
OCCUPIED HEATING SETPOINT” the third
stage of heating will turn off.
•
When the return air temperature is 1.9° F below
the “CV OCCUPIED HEATING” or “CV UN-
OCCUPIED HEATING SETPOINT” the second
stage of heat will turn off.
•
When the return air temperature is 0.1° F above
the “CV OCCUPIED HEATING” or “CV UN-
OCCUPIED HEATING SETPOINT” the fi rst
stage of heating will turn off.
The Simplicity Control has the following heating timing
functions:
•
A minimum off time of 2 minutes.
•
A minimum on time of 3 minutes.
•
There is a 30 second time delay between stag-
es.
VARIABLE AIR VOLUME (VAV)
A Variable Air Volume (VAV) unit can be controlled
by four methods:
•
Stage thermostat
•
Communicated Space Temperature
•
Hardwired Space Temperature
•
Stand Alone - Return Air Temperature
Cooling - Occupied with Thermostat
The following System Parameters must be programmed
through the Simplicity Control for VAV operation:
•
“VAV COOLING SUPPLY AIR TEMP UPPER
SETPOINT” – using Parameter 23 under the
PROGRAM key on the Simplicity control board
or under the COOLING SETUP tab in the Sim-
plicity PC software package.
•
“VAV COOLING SUPPLY AIR TEMP LOWER
SETPOINT” – using Parameter 24 under the
PROGRAM key on the Simplicity control board
or under the COOLING SETUP tab in the Sim-
plicity PC software package.
The Simplicity Control initiates compressor operation
as follows:
•
The Simplicity Control will turn compressors on
and off based of the difference between the sup-
ply air temperature and the cooling set point.
•
With no thermostat call or a Y1 first stage
call the Simplicity Control will control to the
“VAV COOLING SUPPLY AIR TEMP UPPER
SETPOINT”. The Y1 input is not required to
initiate compressor operation.
•
When there is a Y2, Y3, or Y4 call from the
thermostat the Simplicity Control will control to
the “VAV COOLING SUPPLY TEMP LOWER
SETPOINT”.
•
The control uses a 5-degree dead band around
the cooling “VAV COOLING SUPPLY TEMP
UPPER SAT SETPOINT” or “VAV COOLING
SUPPLY AIR TEMP LOWER SETPOINT”.
•
When the supply air temperature is 5.0° F
or more above the cooling “VAV COOLING
SUPPLY TEMP UPPER SAT SETPOINT” or
“VAV COOLING SUPPLY AIR TEMP LOWER
SETPOINT” the Simplicity Control will energize
the fi rst compressor.
•
The control records the supply air temperature
right before the compressor is turned on and
compares it to the supply air temperature after 5
minutes of operation.
•
A second compressor will be turned on if both of
the following criteria are met:
– The supply air temperature is still 5.0° F or
more above the “VAV COOLING SUPPLY
TEMP UPPER SAT SETPOINT” or “VAV
COOLING SUPPLY AIR TEMP LOWER
SETPOINT”.