750-265 44
Fig. 19. DHW pump implementation.
System Pump
The System pump function is implemented as shown in
Fig. 20.
The System pump function turns on with overrun time for LL
master pump demand. If the LL master STAT Input Enable
parameter is enabled then this demand exists if the Stat input
is on and the master has one or more available slaves (firing
or not); if disabled then this pump demand exists if the master
is sending demand and rate to an available slave (which is
firing or preparing to fire). A slave command can also turn on
the pump, either with or without overrun time and it can be
turned on by the exercise pump function.
Table 25. DHW Pump Parameters.
Parameter Comment
DHW Pump Output None, Pump A, Pump B, Pump C
This parameter allows the DHW pump function to be disconnected or to be attached to any of
the pump outputs.
DHW Pump Control On, Auto
The DHW pump can be turned on manually, or it can be set to operate automatically. If it is
turned on, it remains on until changed back to Auto.
DHW Pump Start Delay MM:SS
When DHW demand changes from off to on, this delay time is used to delay the start of the
DHW pump. The pump starts after the delay expires, assuming that DHW demand is still
present. This delay does not occur, however, if the burner is already firing when DHW gains
control of it.
DHW Pump Overrun Time MM:SS
This time indicates how long the DHW pump should remain on after DHW demand ends.
DHW ANTI-COND ENABLED
DHW ANTI-COND ACTIVE
BOILER PUMP
DEMAND AND
STATUS FROM DHW
BOILER PUMP
HAS ITS OWN
OVERRUN TIMER
DEMAND PRIORITY
= DHW
DHW
PUMP
OUTPUT
DHW PUMP CONTROL: ON
(SELECTIONS ARE: ON/AUTO)
AUXILIARY PUMP
DEMAND AND STATUS
FROM DHW
AUXILIARY PUMP
HAS ITS OWN
ON/AUTO CONTROL
DHW HIGH
LIMIT ACTIVE
HIGH LIMIT
INHIBITS THE
PUMP.
DHW FROST PROTECTION PUMP DEMAND
LOAD EXPIRED
START DELAY
FORCE OFF
EXERCISE PUMP DEMAND
DON’T EXERCISE
PUMP IF FORCED
OFF OR START
DELAY IS IN
PROGRESS.
LOAD
OVERRUN TIME
INHIBIT OVERRUN
IF FORCED OFF.
LOAD
OVERRUN TIME
CLEAR (INHIBIT)
TURN ON THE PUMP
FOR DHW DEMAND
(AFTER DELAY) OR
OVERRUN.
BURNER IS FIRING
FORCE EXPIRED
ANTI-SHORT-CYCLE
DELAY INACTIVE OR
NOT APPLICABLE
DHW ANTI-COND “PUMP OFF” SELECTED
FROST PROTECTION
AND OVERRUN
TO BOILER PUMP
M28031
PARAMETER
OTHER NAMES ARE INTERNAL SIGNALS.
CONNECTION TO PUMP A, B, OR C
1–9 ON/OFF PRIORITY.
CIRCLED NUMBERS ARE REASONS WHY PUMP IS ON.
NUMBERS WITHIN SQUARES ARE REASONS WHY PUMP IS OFF.
THE LOWEST NUMBERED REASON THAT EXPLAINS THE
ACTUAL PUMP CONDITION IS USED.
9
7
8
6
4
5
1
3
2
BURNER STATE = OK
• NOT INTERNAL FAULT
• NOT DISABLED (E.G. BURNER SWITCH)
• NOT DISABLED BY PARAM ERROR
• NOT LOCKED OUT
IF THE PUMP IS NOT
FORCED OFF AND IT
SHOULD BE ON,
THEN TURN IT ON.
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