Appendix E Falcon Lead Lag
E-51
Frost protection input to the priority logic is not a heat demand, it is a burner demand (because frost protection
always turns on pumps without regard to the priority control - it is a priority item only if it also wants to fire).
Master Status
MASTER HEAT DEMAND
Is a data item which contains the status for the following sources of demand. All sources that are currently calling
for heat will be true (multiple items may be true at the same time) except when WWSD is active, then CH demand is
inhibited.
CH Demand
CH Frost demand – true if any slave is calling for CH frost protection and Frost protection enable is true.
MASTER ACTIVE SERVICE
Is a data item which contains the identity of a single source of demand that the LL Master is currently serving
according to its priority:
• None – no active service, LL master is idle
•CH
• Frost – burner demand is true for frost protection
• WWSD – no high priority demand is active, and WWSD is inhibiting CH demand (if any).
MASTER SERVICE STATUS
Is a data item used by pump control logic that combines the Master Heat Demand and Master Active Service data.
It is implemented as described by the Pump Control Block diagram.
Outdoor Temperature
For a CB Falcon that hosts a LL master, the outdoor temperature may be known from either of two sources. If the
host has an outdoor sensor that is reporting a valid temperature then this sensor reading is used. Otherwise, if any
slave is reporting a valid temperature as part of its Data Poll message, then this temperature is used.
The resulting outdoor temperature provides all outdoor temperature needs for both stand-alone and LL master pur-
poses. If neither source has a valid temperature then the outdoor temperature is simply invalid and unknown, and
the functions which need this information handle it accordingly per their individual definitions.
Modulation
Each demand source has one or more setpoints that may be active and an operation sensor. These are used to detect
turn-on and turn-off conditions. The difference between operating point and setpoint determines the LL master's firing
rate
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