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External Modulating Control
SECTION XIII - External Modulating
Control
The boiler can directly accept an analog 0-10
VDC signal to control the firing rate from an
external modulating boiler controller such as
the Optima SCC4.
Wiring the Modulating Controller
Run two 18 gauge wires from the external
modulating boiler controller’s 0-10 VDC boil-
er output to the modulation signal terminals on
the low voltage terminal strip inside the boiler.
(see boiler wiring diagram, Fig. 19 page 29).
This signal will both enable and modulate the
boiler. No wiring is required at the thermostat
terminals.
Ensure that the polarity of the connec-
tions from the external modulating boil-
er controller to the boiler are correct.
Reversed polarity will lead to no
response from the boiler.
Trimax Adjustment
The Trimax control must be programmed to
accept the 0-10 VDC signal from the external
modulating boiler control.
1. Use the Heating EZ Setup function to set
the CH Demand to 0-10V Modulation
Signal. Reference page 43 for the Heating
EZ Setup function.
Programming of External Modulating
Control
The external modulating control must be pro-
grammed to send 2 VDC to enable the boiler
and run it at low fire, and 10 VDC to run the
boiler at high fire. Once the control enables the
boiler, it must wait 30 seconds to allow the burn-
er to stabilize before modulating the boiler.
NOTICE
