Wiring Schematic - Aqua-Hot 375-d Service Manual

3. Fill the Aqua-Hot completely with the 50/50 mixture of
antifreeze and water heating solution. This will take
approximately five gallons; look for the solution to enter
the overflow tube attached to the expansion tank con-
nection on top of the Aqua-Hot.
4. When refilling, open the air-release valve located on the
expansion tank connection to release air pockets. Refer-
ence Figure 24. Hold the valve open until all air is re-
leased. Be sure the valve is closed when finished by
hand-tightening. Look for the solution to enter the over-
flow tube attached to the expansion tank connection on
top of the Aqua-Hot.
5. Close the drain valve.
Purging the System by Grounding the Zone
Thermostat Connection:
1. Ensure that the boiler tank has been filled with the ap-
propriate 50/50 mixture of antifreeze and water heating
solution.
2. Locate Terminal Block for switches, heat exchangers,
fans and thermostats. Reference Figure 26.
3. Locate the thermostat connection terminals T1 and T2.
Reference Figure 27.
4. Connect a wire to the desired zone terminal and connect
the opposite end of the cable to a ground source. Refer-
ence Figure 27.
NOTE: The circulation pump will activate as soon as the
terminal is connected to a ground source; therefore,
disconnect the wire from the ground source during
the antifreeze and water heating solution filling pro-
cedure.
5. Allow the circulation pump to operate for approximately
1-3 minutes in order to purge the corresponding heating
loop, then remove the wire from the ground source.
6. Open the drain valve and completely fill the Aqua-Hot's
boiler tank with additional antifreeze and water heating
solution.
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ECTION ILLING THE
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© 2009 Aqua-Hot 375D Hydronic Heating System Service Manual—Rev. A
A -H
QUA OT WITH HEATING SOLUTION
7. Repeat steps 5 and 6 for both heating loops until all air
has been completely bled from the entire heating system.
NOTE: All air is bled from the heating system when the
antifreeze solution enters the overflow tube attached
to the expansion tank connection.
8. Once the systems have been purged, disconnect the wire
from the ground source and the terminal block.
9. Check the Aqua-Hot's expansion tank and top it off to
the cold level mark with the 50/50 antifreeze and water
mixture, if necessary.
10. Ensure that each thermostat's connection wiring is still
in its original configuration. Reference Appendix A.
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