heat-timer Mini-MOD-CNC Installation And Operation Manual page 24

MODULATING OUTPUT TYPE
4–20mA, 0–5V, 0–10V, 1–5V, or 2–10V Outputs
• If either of the Condensing or Non-Condensing Boiler Groups was set to Modulating as
the Boiler Type, the Mini-MOD-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 Mini-Extension, connect it to the Mini-MOD-CNC prior to configuring the
Output Type. Otherwise, the Mini-MOD-CNC might not recognize them properly.
MODULATING MODE
Normal, Parallel
• 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.
• 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 43.
• If Parallel is selected, it is preferred to set the Lag Delay to 0. See "LAG DELAY" on page 35.
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 16.
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24 HEAT-TIMER CORP.
11
MODULATING BOILER SETTINGS
Default: 4–20mA
BACK
Default: Normal
Normla
Parallel
BACK
CONDENSING
OUTPUT A TYPE
4-20ma
0-10v
0-5v
2-10v
1-5v
Not Installed
SELECT
CONDENSING
MODULATING MODE
SAVE
059102-00 REV. C