Appendix E Falcon Lead Lag
E-53
If the setpoint source is S2 4-20mA then the setpoint is determined by the 4-20mA input on S2, and the two param-
eters described below. If the 4-20mA signal goes out of range or is invalid, and this persists for a specified time,
then the setpoint source reverts to "Local". In this case once it has gone to "Local", it remains that way until the 4-
20mA signal is stable again.
LL CH 20MA WATER TEMPERATURE: TEMPERATURE OR NONE
CH 4MA WATER TEMPERATURE: TEMPERATURE OR NONE
These provide the 20mA and 4mA temperatures for the interpolation curve. If either of these have the None value,
are invalid, are out of range, or are too close for interpolation, an alert is issued and the setpoint reverts to "Local"
when it is selected as 4-20mA.
LL CH SETPOINT: DEGREES OR NONE
This setpoint is used when the time-of-day input is off. If the ODR function is inactive then the setpoint is used as-is.
If the ODR function is active then this setpoint provides one coordinate for the outdoor reset curve.
LL CH TOD SETPOINT: DEGREES OR NONE
This setpoint is used when the time-of-day input is on. If the ODR function is inactive then the setpoint is used as-is.
If the ODR function is active then this setpoint provides one coordinate for the shifted (because TOD is on) outdoor
reset curve.
TIME OF DAY
The Time of Day has one sources of control: a switch contact. Closed TOD is an on condition; open, then TOD is
off.
OUTDOOR RESET AND BOOST (BOOST IS FUTURE)
The outdoor reset and boost functions for the LL CH functions will be implemented as described for a stand-alone
CH loop.
Each of the loops which implements outdoor reset and boost has its own parameters. The parameters used by the
LL master are:
• LL setpoint
• LL CH TOD Setpoint
• LL Outdoor reset enable: Disable, enable
• LL CH ODR minimum outdoor degrees or None
• temperature:
• LL CH ODR maximum outdoor degrees or None
temperature:
• LL CH ODR low water temperature: degrees or None
• LL CH ODR boost time: mm:ss or None
• LL CH ODR boost max setpoint: degrees or None
• LL CH ODR boost step: degrees or None
• LL CH ODR boost recovery step time:mm:ss or None
The outdoor reset function requires the outdoor temperature. This temperature may be obtained from either a local
sensor or a LL slave as described earlier.
If the outdoor temperature is invalid and unknown, then no outdoor reset
action occurs and an alert is issued indicating an invalid outdoor temperature.
LL CH ODR MINIMUM WATER TEMPERATURE: DEGREES OR NONE
This specifies the minimum outdoor reset setpoint for the LL master. If the outdoor reset function calculates a tem-
perature that is below the temperature specified here, then this parameter's temperature will be used.
If this parameter is invalid or None then the outdoor reset function will be inhibited and will not run: if it is enabled
then an alert is issued.
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