LAARS M4-LHS - Installation Manual - Manual (Page 33)

HT# 059295-00
A
M4-LHS installation and Operation Manual
33
MODuLaTiNg BOiLEr OPEraTiNg SETTiNgS
gain
Adjustable from -10 to +10 Default: 0
Button: MENU/<System Settings>/<More Settings>/<Modulating Settings>/Gain
• The Gain adjusts the aggressiveness of the modulating PID logic. It controls how much
modulation is changed when the system temperature is different from the Set Point.
• A Gain of 0 is a good starting point for all systems.
• If during normal load conditions, the system temperature tends to oscillate significantly,
decrease the Gain by two numbers (for example, from 0 to -2). Wait for at least 15 minutes
before evaluating how the change has affected the system.
• If during normal load conditions the system temperature tends to remain consistently below
the Set Point (or consistently above the Set Point), increase the Gain by two numbers (for
example, from 0 to 2). Wait for at least 15 minutes before evaluating how the change has
affected the system.
MODULATION SETTINGS
Gain +0
Lag Delay 0min
Soft-Off Delay 45sec
BACK ▲ ▼ SAVE
------ GAIN ------
+0
[ ]
BACK ▲ ▼ SAVE
Lag Delay
Adjustable from 0min to 60min Default: 0min
Button: MENU/<System Settings>/<More Settings>/<Modulating Settings>/Lag Delay
• The Lag Delay requires the lead stage to remain at 100% modulation for the full period of
the Lag Delay before the lag stage can be activated. For example, if the Lag Delay was
set to 10 minutes, the Lead Stage must remain at 100% modulation for the full ten minutes
before the lag stage could be activated. The Message Display Line will display Lag
Delay and the remaining time.
• The Lag Delay is useful in installations where one unit should usually have enough output
to hold the load unless it fails or load conditions become extreme.
• The Lag Delay overrides the Modulation Start % selected for each stage. Regardless of
that setting, the previous stage must reach and stay at 100% before the lag stage can be
activated.
• The full Lag Delay must elapse regardless of what happens to the system temperature.
Therefore, set the Lag Delay to 0 minutes to achieve smooth operation.
• Note that if Parallel was selected as the Modulation Mode (See "Modulating Logic
Overview" on page 4), this value must be set to 0 minutes to avoid having the lead boiler
going to 100% modulation prior to firing the lag boiler.
---- LAG DELAY ----
0 min
[ ]
BACK ▲ ▼ SAVE
Soft-Off Delay
Adjustable from 0sec to 60sec Default: 10 sec
Button: MENU/<System Settings>/<More Settings>/<Modulating Settings>/Soft-Off Delay
• When a boiler is no longer needed, the Soft-Off keeps that boiler in Low Fire prior to
turning it off.
• The display will show a percent that is equal to the Ignition % for the stage in Soft-Off
delay. That number will blink for the Soft-Off delay period.
• If during the Soft-Off delay period the M4-LHS needed that stage to turn back on, the stage
will be released from the Soft-Off delay and resume normal operation.
• On a Shutdown initiation or Tstat termination any stage that was On will go into Soft-Off
delay before fully turning off.
-- SOFT-OFF DELAY --
10 sec
[ ]
BACK ▲ ▼ SAVE
aLErT
When using Soft-Off and Last Stage Hold, the last boiler will not turn off until both
parameters have elapsed. In this case, Soft-Off will start after the Last Stage Hold.