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stat can be used for summer/winter changeover. ON (closed) is winter
heating mode and OFF (open) is summer cooling mode.
purge cycle operation: With a pipe sensor connected, this thermostat
will initiate a purge cycle if the sensed water temperature is ambiguous
(not adequately hot or cold). The purge cycle algorithm can be either
temperature or time based, depending on the configuration of Service
Menu 16.
Temperature-Based Purge:
•
When an Ambiguous mode is detected and a demand exists, a 3
minute purge timer begins and the Main Output is opened.
•
After the 3 minute purge cycle, the thermostat checks again to see
if the water temperature is more than 15°F from set point, or above
80°F or below 60°F.
•
If Winter or Summer mode is determined, normal HVAC operation
occurs. If still ambiguous, the thermostat checks to see if the COIL
temperature is below 60°F or above 80°.
Coil < 60°F = Summer Mode.
Coil > 80°F = Winter mode.
•
Purge Cycle is repeated until a non-ambiguous condition is
sensed.
NOTE: If at any time the demand goes away, the thermostat will abort
the purge cycle.
Time-Based Purge: (Default)
•
The time-based purge cycle will start a 3-min purge cycle and
enable the Main Output if any of the following conditions occur:
transition from OFF to AUTO mode, Reset event, power cycle, and/
or 1-hour timer expires.
•
After the 3 min purge cycle, a pipe sensor reading says:
Pipe is 15°F+ below the zone temp = Summer mode
Pipe is 15°F+ above the zone temp = Winter mode
Pipe is within 15°F of zone temp = still Ambiguous
•
If a Winter or Summer mode is determined, the appropriate
heating/cooling occurs. The thermostat will purge and check pipe
temperatures again after 1-hour.
•
If step 2 is still ambiguous, all thermostat outputs are disabled for
1 hour.
•
After 1 hour, the purge cycle resumes at step 1.
HVac setback systems
Setback Operation - Remove JP3
This is a low level input that is normally open. When switch is closed, the
T180 heating and cooling setback limits are used as temperature control
points. Fan operation in setback is cycled with demand. Pressing any
button will override setback for 1 hour. Setback will override any user
setting unless control is turned to OFF.
Intelligent Occupancy Sensors like the SD200-001 and SD200-002 can be
used with this input to set the HVAC system to control at setback limits.
Occupancy Operation – Install JP3
The T180 can be used with PECO S200 series occupancy detection
equipment. The occupancy and switch inputs are designed to connect to
the SB200 slave sensor and SE200 door switch.
•
The Occupancy Sensor is a low-level switch that is open when
there is occupancy and closed when unoccupied.
•
The Door Switch is a low-level switch that is open when the door
© COPYRIGHT 2008 PECO, INC. ALL RIGHTS RESERVED.
is open and closed when the door is closed. This system requires
both an Occupancy Sensor and a Door Switch.
Operation From an Occupied Mode:
1.
The T180 operates normally and looks for a door close. A door
close signal initiates an occupancy status detection.
2.
If occupancy is detected, the T180 will maintain normal HVAC
control. It then waits for a door open signal before determining
occupancy again.
3.
If no occupancy signal is detected within 2 minutes, the T180
changes to unoccupied mode and controls at setback temperature
values.
Operation From an Unoccupied Mode:
1.
In an Unoccupied State, the T180 sets heating and cooling set
points to setback values, as determined in the service menu. In
this mode, the fan is automatically set to cycle with demand.
2.
The T180 will continually monitor the room for occupancy.
3.
Any occupancy detection, including door open, will set the operation
to occupied mode.
In either mode, if the door is left open for more than 2 minutes the T180
will disable the HVAC system. A one-time ten minute override can be
initiated by pressing any thermostat key pad.
Door Switch Only Operation - Install JP3. A stand alone door or window
switch can be connected to the T180 to disable the HVAC system (outputs)
if a door or window is left open for more than 2 minutes. A one-time ten
minute override can be initiated by pressing any thermostat key pad.
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