HT# 059299-00 A
• Using the same example, as the load decreased, Stage "B" would
modulate down to its Ignition % Stage "A" would then modulate down to
30% Only then, Stage "B" turns off
• If the Lag Delay is set to anything other than 0, a stage must always
go to 100% modulation before the next stage is activated However,
the Modulation Start should still be set correctly as it is used during
modulation reduction
• The Modulation Start will generally be set differently based on the
Modulating Mode:
• Lower Modulation Start setting allows the lag boiler to be activated and
warmed up early for smoother output and better target control
• Higher Modulation Start settings can prevent unnecessary stages from
being activated
• Some general guidelines to follow:
○ Less than 50% - not recommended in the Normal Modulating Mode
○ 50-70% - These lower settings might be used in an application that
has wide load swings such as an industrial plant or a hospital This
allows an additional boiler to be brought on line before the previous
boiler has begun to reach its capacity
○ 70-90% - This range is recommended for most applications When
there are several stages of relatively equal capacity and all can be
used to hold the load, this allows some degree of overlap, without
activating unnecessary stages
○ 90-100% - Recommended when one stage can always handle the
load while the other stages are mainly used for backup
• The Modulation Start should be set to the maximum value where the unit
runs most efcient
○ Less than 30% - These lower settings are recommended for
condensing boilers with high turn-down ratios of 4 to 1 or greater
○ 30-50% - These settings are recommended for the rest of all
condensing boilers
STAGE MENU/Copy Settings
• This option copies only the Ignition % and Modulation Start from stage
"A" to the rest of the stages
COPY STAGE A
SETTINGS
to all Stages
The Mode must be set for each
stage The Copy Settings
command will not set the Mode
for the rest of the stages
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