TriangleTube Prestige Slol 250, Installation And Maintenance Manual

Page: 60 / 89

54
External Modulating Control
SECTION XII - EXTERNAL MODULAT-
ING CONTROL
The boiler can directly accept an analog 0-10
VDC signal to control the firing rate from an
external modulating boiler controller.
Wiring the Modulating Controller
Run two 18 gauge wires from the external
modulating boiler controllers 0-10 VDC boiler
output to the external input terminals on the
low voltage terminal strip inside the boiler. (see
boiler wiring diagram, Fig. 20 page 32). This
signal will both enable and modulate the boil-
er. No wiring is required at the thermostat (T-
T) terminals 7 and 8 of the boiler.
Ensure that the polarity of the connec-
tions from the external modulating boil-
er controller to the boiler is correct.
Reversed polarity could lead to erratic
and/or no response from the boiler con-
troller.
Parameter Adjustment
The Prestige MCBA control module must be
programmed to accept the 0-10 VDC signal
from the external modulating boiler control.
CH Operating Signal Section
(Parameter 45)
Follow the procedure for entering the MCBA
Access Code on page 52, and then change the
setting of Paramater 45 from the factory setting
of 00 to 02.
Ensure that Parameter 4 is set above the
highest setpoint of the external modulat-
ing control. Paramater 4 is a boiler high
temperature limit when using an exter-
nal modulating controller.
Programming of External Modulating
Control
The external modulating control must be pro-
grammed to send 1.8 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 2 minutes to allow the burn-
er to stabilize before modulating the boiler.
NOTICE
NOTICE