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Part number 550-100-252/0520
– 42 –
Field wiring See wiring diagrams, Figure 21, page 30 & Figure 23, page 32 (continued)
I. Closure switch (flow switch and/or CAD)
– OPTIONAL
Jumper on Terminal Strip P11
1. A flow switch or combustion air damper (CAD) interlock can be configured by
removing jumper.
2. No control settings are required when using a flow switch.
3. Recommended configuration of the
Unity
TM
control for a CAD interlock:
a. Assign INPUT 3 as a AUX PUMP/ OUTPUT function.
b. For the AUX PUMP/OUTPUT operating mode, select Damper Control.
This ensures the damper will be activated any time the boiler is called on to fire.
c. OUTPUT 3 will provide 120VAC to the damper motor. Use an isolation relay if
damper motor requires another voltage or more than 2.2 amp if using 120VAC.
*
The devices used must provide electrically isolated contacts, be-
cause the P11 jumper circuit carries 24VAC.
4. When a call for heat occurs, the corresponding output(s) energize, and the blower does
not activate until the closure switch is made. The boiler is given four (4) minutes to
make the closure switch. If the switch opens prior to ignition, the timer continues with
the blower remaining active. After four (4) minutes, if the closure switch is not made,
or if the closure switch opens during burner firing, the control locks out. The fault will
clear when the closure switch makes The corresponding output(s) will remain energized
in an attempt to close the switch.
See Figure 21, page 30 for details.
J. Closure switch (flow switch and/or CAD)
– with shared end switch – OPTIONAL
1. A flow switch or combustion air damper (CAD) interlock can be configured by
removing jumper.
2. No control settings are required when using a flow switch.
3. Recommended configuration of the
Unity
TM
control for a CAD interlock installed
on individual boiler.
a. Assign INPUT 3 as a AUX PUMP/ OUTPUT function.
b. For the AUX PUMP/OUTPUT operating mode, select Damper Control.
This ensures the damper will be activated any time the boiler is called on to fire.
c. OUTPUT 3 will provide 120VAC to the damper motor. Use an isolation relay if
damper motor requires another voltage or more than 2.2 amp if using 120VAC.
*
The devices used must provide electrically isolated contacts, be-
cause the P11 jumper circuit carries 24VAC.
4. Recommended configuration of the Unity
TM
control for a shared end switch device:
a. Assign INPUT 2 as a AUX PUMP/ OUTPUT function on the boiler with the
end switch.
b. For the AUX PUMP/OUTPUT operating mode, select ANY Burner
Demand. This ensures the end switch will be activated any time any burner is
called on to fire. See other AUX PUMP/ OUTPUT options in Figure 45, page 66.
c. OUTPUT 2 will provide 120VAC to the shared device. Use an isolation relay if
shared device requires another voltage or more than 2.2 amp if using 120VAC.
5. When a call for heat occurs, the corresponding output(s) energize, and the blower
does not activate until the closure switch is made. The boiler is given four (4)
minutes to make the closure switch. If the switch opens prior to ignition, the timer
continues with the blower remaining active. After four (4) minutes, if the closure
switch is not made, or if the closure switch opens during burner firing, the control
locks out. The fault will clear when the closure switch makes The corresponding
output(s) will remain energized in an attempt to close the switch.
*
The devices used must provide electrically isolated contacts, be-
cause the P11 jumper circuit carries 24VAC.
• Shared devices could be a louvered wall or other shared device that end switch
verification is required.
SVF
™
Series 1
COMMERCIAL CONDENSING GAS-FIRED WAT ER BOILER
— Advanced Manual
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