heat-timer Mini-MOD-CNC Installation And Operation Manual page 25

SEQUENCING OUTPUT TYPE
On/Off, 2-Stage, 3-Stage, 4-Stage Outputs
• The Mini-MOD-CNC can sequence any type of multi-stage boiler starting with a single
On/Off and up to a 4-stages. Just select the number of stages per boiler from this
menu option.
• The number selected applies to all sequencing boilers within that group whether it is
condensing or non-condensing.
STAGING MODE
Lo/Hi/Lo/Hi, Lo/Lo/Hi/Hi
• During low load conditions, some boilers run more efficient when the lower stages are
energized alone than with the higher stages. For these types of boilers select Lo/Lo/Hi/Hi.
Then, the Mini-MOD-CNC will sequence the lower stages of all boilers their Mode is set to
Auto before sequencing the higher stages.
• For the rest of the boiler types, the Lo/Hi/Lo/Hi should allow the staging of the lower stage
of the lead boiler followed by the higher stage of the same boiler. Then when more stages
are needed, it will fire the lower stage of the lag boiler followed by the higher stage of the
lag boiler.
PROVE/DOMESTIC HOT WATER (DHW) PRIORITY
Prove, DHW Priority, DHW No Priority, No Priority (Summer) Default: Prove
Button: MENU/<System Startup>/.../Prove-DHW Sharing
• This setting determines the functionality of Input Terminals 29 and 30.
• When Prove is selected, the Mini-MOD-CNC will not start any boiler unless Prove terminals
are shorted/closed. However, it will allow the System relay to function normally.
• Using the terminals to connect to an aquastat for a Domestic Hot Water call and selecting
any of the DHW options will raise the calculated water temperature to the DHW Set Point
(See next setting).
• The Domestic Hot Water Priority option de-energizes the System relay during domestic
hot water calls for a period of one hour. If after the priority period the DHW call did not
expire, the System relay will energize providing heat to the building and the temperature
target will remain at the DHW Set Point. After the DHW call ends, the set point will drop
to satisfy the reset ratio or set point.
• Domestic Hot Water No Priority option allows the System relay to remain energized during
a domestic hot water call (aquastat call on terminals 29 and 30). However, in Summer,
Shutdown, No Tstat call for heat, or when outdoor temperature is above Outdoor Cutoff,
a DHW call will energize the System relay. After the DHW call terminates, the System relay
will continue to run for the System Run-On period before turning off.
• Domestic Hot Water No Priority (Summer) behaves the same as the DHW No Priority.
The only difference is that in Summer, Shutdown, No Tstat call for heat, or when outdoor
temperature is above Outdoor Cutoff, a DHW call WILL NOT energize the System relay
except for the Run-On delay after the DHW call ends.
059102-00 REV. C
12
SEQUENCING BOILER SETTINGS
Default: Lo/Hi/Lo/Hi
Default: On/Off
On/Off
2-Stage
3-Stage
4-Stage
BACK
LO/HI/LO/HI
LO/LO/HI/HI
BACK
Prove
DHW Priority
DHW No Priority
No Priority (Summer)
BACK
NON-CONDENSING
OUTPUT TYPE
SAVE
NON-CONDENSING
STATING MODE
SAVE
PROVE/DHW SHARING
SAVE
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HEAT-TIMER CORP. 25