LAARS M4-LHS - Installation Manual - Manual (Page 40)

HT# 059295-00
A
40
M4-LHS installation and Operation Manual
Auto The M4-LHS will control the boiler’s operation to maintain the desired Set Point. Only boilers set to Auto can be Lead
boilers.
Standby Standby boilers can only be activated when all boilers in Auto have been at 100% modulation or at High fire for the full
Standby Time. Standby is generally used when you want a specific boiler to be available in extreme load conditions. Note
that a Standby boiler Cannot be a Lead boiler.
Manual Available For modulating boilers only. The Manual Mode should only be used when testing a boiler. Manual overrides the
Prove input. For modulating boilers, the exact percent of modulation for a boiler can be set with the Manual mode. Once
selected, the unit will immediately turn on and modulate to the selected percentage. See "Boiler Status" on page 38.
Off Any stage output not connected to a physical stage should be set to Off. The Off Mode can also be used to disable units
that are being serviced.
On This mode should only be used when testing a boiler. This mode overrides the PROVE input, Season setting, Shutdown or
Tstat status, and Sensor Fault status. Once set to On the boiler will immediately start firing at its highest rate.
ignition %
(Modulating Boilers Only)
0-10VDC Adjustable from 1% to 50% Default: 1%
1-10VDC Custom Adjustable from 5% to 70% Default: 25%
Button: STAGE/Ignition %
• The Ignition % of a boiler is the lowest percent of modulation that boiler can achieve. That
is for the 4-20mA and 0-10VDC if the Ignition % was set to 20%, the 0-10VDC terminals
will output 2VDC. The 4-20mA terminals will output 7.2mA.
• The 1-10V custom boiler types will use the Ignition % when the boiler is activated. In this
case, the Ignition % will be the level at which the control will output 1VDC.
• During the Soft-Off Delay, the boiler will remain at the Ignition % before turning Off.
STAGE A
- IGNITION POINT -
25%
[ ]
BACK ▲ ▼ SAVE
Modulation Start %
(Modulating Boilers Only)
Adjustable from 0% to 100% Default: 75%
Button: STAGE/Mod Start %
• The Modulation Start determines at what modulation percent the previous boiler (lead
boiler) should be for the lag boiler to be activated.
• For example, if the Modulation Start for Boiler B is set to 50%, then when Boiler A reaches
75% modulation (50% Mod Start % + 25% Ignition % = 75%), Boiler B will be brought on.
STAGE A
MODULATION START
75%
[ ]
BACK ▲ ▼ SAVE
• When modulation is decreasing, the lag unit will remain on at the Ignition % modulation until the previous boiler reaches 40% of
lag boiler's Modulation Start, or 2% above the Ignition Point, whichever is higher.
• Using the same example, as the load decreases, Boiler B will modulate down to its Ignition %. Boiler A will then modulate down
to 30% (75% x 40%). Only then will Boiler B turn off.
• If the Lag Delay is set to anything other than 0, the lead boiler must reach 100% modulation before the lag boiler is activated.
However, the Modulation Start % should still be set correctly, because it will be valid when modulation is decreasing. "Lag Delay"
on page 33
• Laars suggests that when Parallel is selected as the Modulation Mode to set the Modulation percent equal to or slightly higher
than double the Ignition %. This way, the lag boiler will only start if the load is large enough for two boilers to run at the lowest
modulation. See "Modulating Logic Overview" on page 4.
Copy Settings - Boiler a Only
(Modulating Boilers Only)
Button: STAGE/Copy Settings
• If all the active modulating boilers are to be set to the same Ignition % and Modulation %,
they can be set for Boiler A and then copied to the other modulating boilers.
• It is still required to select the Mode for all other boilers as the Mode is NOT copied.
aLErT
The Mode MUST be set for each boiler. The Copy Settings command will not set the
Mode for the remaining boilers. Only Ignition % and Modulation Start % are copied.
-- COPY SETTINGS --
From Stage A to
all other stages
BACK COPY