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Figure 38: Wiring for MCBa Modulating Boiler Control Time Delay Relay Box
5. If the boiler installation site may be subject to low
supply voltage conditions or “brownouts”, that
would affect MCBA Modulating Boiler Control
operation, a separate optional Time Delay Relay
Box (P/N 101693-01) installation is strongly
recommended. See Figure 38 “Wiring for MCBA
Modulating Boiler Control Time Delay Relay Box”
and follow the following installation steps:
a. Turn off power to boiler.
b. Remove 120 volt power wiring, L1, L2 and
ground.
c. Remove cover to MCBA Time Delay Relay Box.
d. Mount MCBA Time Delay Relay Box on secure
surface near boiler.
e. Connect wiring to MCBA Time Delay Relay Box
as per wiring diagram (Figure 38).
f. Connect additional eld wiring (not included
in the kit) from MCBA Time Delay Relay Box
to 120 volt power wiring as per wiring diagram
(Figure 38).
g. Install cover on MCBA Time Delay Relay Box
and restore power to boiler.
h. Measure time from when power is restored until
the boiler actually powers up (LED numbers
will reappear on MCBA display panel). This
MCBA Time Delay Relay Box has a delay on
make timer that delays powering of the boiler for
3 minutes whenever power is lost to the boiler.
Timing should be approximately 3 minutes, but
no longer than 4 minutes.
i. Cycle boiler per installation manual.