LAARS M4-Ext - Installation Manual - Manual (Page 18)

18
MOdULATiNg BOiLER SETTiNgS
MOdULATiNg OUTPUT TYPE
4-20mA, 0-5V, 0-10V, 1-5V, or 2-10V Outputs Default: 4-20mA
• If either of the Condensing or Non-Condensing Boiler Groups was set to Modulating as the
Boiler Type, the M4-CNC will offer the capability of controlling a variety of modulating
signals. Each boiler can be configured to have a different modulating signal.
• The modulating output for each boiler can be configured to 4-20mA operation (Current)
or any of the voltage ranges (0-5V, 0-10V, 1-5V, 2-10V). Check the modulating boiler to
determine its control requirements.
• When using the M4-Extension, connect it to the M4-CNC prior to configuring the Output
Type. Otherwise, the M4-CNC might not recognize them properly.
MOdULATiNg MOdE
Normal, Parallel Default: Normal
• Some modulating boilers perform better at higher modulation. For these units, it is
advantageous to run one unit at high modulation than several units at lower modulation. If
the units used are of this type, select Normal. This is the recommended setting for typical
steel and cast iron boilers or boilers with low turndown ratios.
CONDENSING
-- OUTPUT A TYPE --
4-20ma
0-10v
0-5v
2-10v
1-5v
Not Installed
BACK ▲ ▼ SAVE
WARNiNg
Make sure that boiler
modulation wiring matches the
signal selected. Warranty will
not cover failed components
caused by improper wiring.
See "Wiring to Modulating
Output" on page 13.
CONDENSING
- MODULATING MODE -
Normal
Parallel
BACK ▲ ▼ SAVE
• There are many condensing boilers that run more efficiently at lower modulation. If it
is more energy efficient to run several units at lower modulation than one at high, select
Parallel. This is typically used on water-tube boilers, low mass boilers, or boilers with high
turndown ratios.
• For best Parallel performance, set the Modulation Start % to be equivalent to the lowest
firing rate of the boiler multiplied by 2. That is, if the lowest firing of the boiler was 20%,
set your Modulation Start% to 40%. See "Modulation Start %" on page 32.
• If Parallel is selected, it is preferred to set the Lag Delay to 0. See "Lag Delay" on page 26.
LAARS Heating Systems
HT# 059104-00 B