Falcon Lead Lag Appendix E
E-50
CH Demand
LL CH DEMAND SWITCH: DISABLE, STAT, ENVIRONCOM REMOTE STAT
The inputs that can function as the CH demand switch are: STAT, EnvironCOM Remote Stat. If the CH demand
switch value is Disable, the LL master does not respond to CH demand.
Warm Weather Shutdown
WARM WEATHER SHUTDOWN ENABLE: DISABLE, SHUTDOWN AFTER DEMANDS HAVE ENDED,
SHUTDOWN IMMEDIATELY
WARM WEATHER SHUTDOWN SETPOINT: TEMPERATURE OR NONE
When warm weather shutdown is Disabled then it has no effect (i.e. the Warm Weather Shutdown (WWSD) status
shown on the priority diagram is false).
These two parameters are shared by the stand-alone control and the LL master and have the same effect for either
control.
This function requires the outdoor temperature. This temperature may be obtained from either a local sensor or a
LL slave. If WWSD is enabled but the outdoor temperature is invalid and unknown, then the WWSD function acts as
if it is disabled and has no effect and an alert is issued indicating an invalid outdoor temperature.
If it is enabled then it uses a 4°F (2.2°C) hysteresis:
If WWSD is false, then when the Outdoor temperature is above the value provided by Warm weather shutdown
setpoint then:
If "Shutdown after demands have ended" is selected then any current CH demand that is present prevents
WWSD from becoming true; that is if CH demand is false then WWSD becomes true.
Otherwise if "Shutdown immediately" is selected then WWSD becomes true, it immediatetly causes CH
demand to end.
If WWSD is true, then when the Outdoor temperature is below the value provided by Warm weather shutdown
setpoint minus 4°F (2.2°C) then WWSD becomes false.
When warm weather shutdown is true then:
New occurrences of CH demand is inhibited.
DHW demand is not affected.
Frost protection
LL master frost protection is enabled with Frost protection enable: Disable, Enable
The need for frost protection is actually detected independently by each slave which notifies the master whether
frost detection occurred in CH frost detection, and/or its DHW frost detection, and whether it is severe enough to
require burner firing as well as pump operation. This is done via its Slave status parameter.
If Frost protection enable is Enable then the master's Slave write message, will indicate CH or DHW frost protec-
tion or both as read from each slave's Slave Status. This will cause any slave pumps which are enabled to follow
this status to turn on without any other action required from the master.
If any slave is indicating CH or DHW frost protection, and additionally that slave's Slave status register indicates
burner firing is requested then the LL master's frost protection burner demand will be true.
If the priority scheme allows the master to honor this demand, then it will fire a single burner (the current lead burner
as specified by the sequencer) at the rate indicated by Frost protection rate: 0-100%. (100% represents 100%
firing of this boiler, and where 0% or any value less than the boiler's minimum firing rate represents the minimum
firing rate).
Priority Control
CH heat demand is a simple signal such as STAT, EnviroCOM remote stat, or Warm Weather Shutdown.
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