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Date: 8-4-2010
Revision: 0
Form: 2396
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 Sola 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 protection 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, Enviro- COM remote stat, or Warm
Weather Shutdown.
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
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