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© 2011
D 406 - 12/11
Boiler Minimum Modulation
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The Minimum Modulation is the lowest signal the control can
send to modulate the boiler. This operates the boiler at low
fire. Use the MIN MOD setting in the Adjust Menu to select
an appropriate boiler minimum modulation.
Refer to the boiler manufacturer’s literature to determine the
minimum output voltage V (dc) or current (mA) that the boiler
will successfully operate at.
For 0-10 V (dc):
Minimum Modulation =
Boiler’s Minimum Input Signal
x 100%
10 V (dc)
•
Setpoint Operation
Section H
Setpoint Calls
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A Setpoint Call is required in order for the control to provide
heat to a setpoint load, such as a spa, pool, or snowmelt load.
Once the control registers a setpoint Call, it will display the
Setpoint icon in the “Calls” box of the status field. This can be
done in two ways:
Setpoint
Status Field
Contact Closure
A dry contact is applied across the Setpoint Call terminals
on the 406.
Use the SETPOINT setting in the Adjust Menu to set the
boiler target required to satisfy this setpoint call.
tekmarNet
®
Setpoint Control with Sensor
A Setpoint Call is provided through the tekmarNet
®
system.
This can be done through the tN4 Expansion terminals with a
setpoint device such as a Setpoint Control 161 or 162.
When using a tekmarNet
®
Setpoint Control, the boiler
target is set to the devices Exchange Supply setting.
•
•
Note:
Setpoint operation has no priority.
Boiler System
Pump
Setpoint
Pump
Setpoint
ON
ON or OFF
Zone
Pump
ON or
OFF
Setpoint Operation
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------------------------------
The control can operate to satisfy the requirements of a
setpoint call on the boiler loop in addition to a space heating
call, DHW call or Backup call. A setpoint call overrides
the current boiler outdoor reset temperature and WWSD
setting in order to provide heat to the setpoint load.
When the control receives a Setpoint Call:
The boiler will operate to maintain the Setpoint tempera-
ture set in the Adjust Menu, or on the tekmarNet
®
Setpoint
control.
The Boiler System Pump does not turn on, but may oper-
ate based on either a Boiler, DHW or Backup Call.
It is assumed that the Setpoint pump will provide adequate
flow through the setpoint load and the boiler.
Setpoint calls will also be responded to when the system is
in
Away
, which can be set using a 479 User Switch.
•
•
For 4-20 mA:
Minimum Modulation =
Boiler’s Minimum Input Signal - 4mA
x 100%
16 mA
Example:
A boiler requires a 1.8 V (dc) signal to fire the boiler at low fire.
The boiler can be modulated to 10 V (dc) where it reaches
high fire.
Minimum Modulation =
1.8 V x 100% = 18%
10 V
1.8 V (dc)
10 V (dc)
Control
Rang
e
Boiler
Rang
e
0 Vdc
18%
Boiler Modulation Delay
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The modulation delay is determined by the boiler manufacturer.
It is the amount of time that the burner must operate before
the internal boiler control allows an external signal to operate
the burner.
Use the MOD DELAY setting in the Adjust Menu to select an
appropriate modulation delay time.
