Hot Water Freeze Protection Using Ra Operation; Smoke Purge Operation - York J Series Manual

Unit Sequence of Operation
The cooling and heating operation will be as follows:
• If the SAT increases above the Cmfrt Vent High SAT
setpoint for more than 5 minutes:
• If heating is ON, destage a heating stage.
• At 5 minute intervals, repeat this test until all
heating stages are OFF.
• If heating is OFF, stage a compressor ON.
• At 5 minute intervals, repeat this test until SAT
is below the Cmfrt Vent High SAT setpoint .
• If the SAT decreases below the Cmfrt Vent Low SAT
setpoint for more than 5 minutes:
• If cooling is ON, destage a compressor.
• At 5 minute intervals, repeat this test until all
cooling stages are OFF.
• If cooling is OFF, stage a heating stage ON.
• At 5 minute intervals, repeat this test until SAT
is above the Cmfrt Vent Low SAT setpoint.
As the heating stages, or compressors are staged up, or
destaged, the economizer controls continue using the
economizer damper to "trim" the effect of the staging
and to maintain the SAT as near the middle of the SAT
control band as possible.
If the unit is using hydronic heat, the control will mod-
ulate the water valve to maintain SAT at the programmed
Cmfrt Vent Low SAT setpoint. At this setpoint, the hy-
dronic heat control does not conflict with the economizer
control, and will prevent SAT from dropping outside
of the specified control band when the economizer can
no longer maintain the SAT at its middle-of-the-band
setpoint.
HOT WATER FREEZE PROTECTION USING
RA OPERATION
When programmed for Hot Water or Steam, RA mon-
itoring will be used for freeze protection. If the RA
temperature is less than 40°F and the Supply Fan is OFF,
the Heating Valve output will open to 100%.
When the Supply Fan is ON, or the RA temperature
is greater than 50°F, the Heating Valve output returns
to normal operation. No fault is generated by this
operation.
36

SMOKE PURGE OPERATION

The Smoke Purge Operation will have five selectable
options.
Setting #1, Shutdown
If the smoke purge setting is set to 1 and the Smoke
Purge input is activated, the unit will do the follow-
ing:
• Disable the Exhaust Fan, if activated.
• Disable the Supply Fan, if activated.
• Close the Outside Air damper(s).
• Open the Return Air damper.
Maintain this operation until the Smoke Purge input is
deactivated, then return to normal operation.
Setting #2, Pressurization
If the smoke purge setting is set to 2 and the Smoke
Purge input is activated, the unit will do the follow-
ing:
• Disable the Exhaust Fan, if activated.
• Turn ON the Supply Fan full (VFD to 100%).
• Energize the VAV Heat Relay and drive all VAV
boxes open.
• Open the Outside Air dampers full.
• Close the Return Air damper full.
Maintain this operation until the Smoke Purge input is
deactivated, then return to normal operation.
Setting #3, Exhaust
If the smoke purge setting is set to 3 and the Smoke
Purge input is activated, the unit will do the follow-
ing:
• Disable the Supply Fan.
• Close the Outside Air damper(s).
• Turn ON the Exhaust Fan full (VFD/ED to
100%).
Maintain this operation until the Smoke Purge input is
deactivated, then return to normal operation.
FORM 100.50-NOM7 (808)
JOHNSON CONTROLS