Service manual

— Page 26 —
© January 2013 Aqua-Hot
®
600-D01 Series Hydronic Heating System Service Manual - Rev. A
SECTION 4: AQUA-HOT COMPONENTS
AC High-Limit Thermostat: Left Electric
Element
The AC high-limit thermostat serves as a safety measure in
the event that the electric heating element continues to oper-
ate after the maximum operating temperature is reached.
The high-limit thermostat allows the current for the heating
element to pass through it until the boiler tank reaches a tem-
perature of 220°F. Should this temperature be reached, the
high-limit thermostat blocks the current to the element,
which prevents it from continuing to provide heat to the boil-
er tank.
Troubleshoot the AC high-limit thermostat for the Left Elec-
tric element if the following condition has occurred:

The Left Electric Heating Element fails to operate.
Troubleshooting:
1.
Disconnect all power supplies.
2.
Remove Thermostat Access Panel
3.
Verify that the boiler tank’s temperature is below 220°F.
4.
Locate the AC high-limit thermostat for the left electric
element and remove its wires.
5.
Using an digital Voltage Meter, check the thermostat for
continuity.
If there is no continuity, press the white reset button on
the thermostat and re-check for continuity.
If continuity is still not present after the reset button has
been pressed, follow the instructions in this section to
replace the AC high-limit thermostat.
NOTE: If the high-limit thermostat has tripped, , trouble-
shoot the control thermostat, and verify the boiler tank is full
of the antifreeze-water solution.
Replacement Procedure:
FAILURE TO DISCONNECT ALL POWER SUPPLIES AND/OR
TO ALLOW THE HEATER TO COOL BEFORE SERVICING
COULD CAUSE SERIOUS DAMAGE OR PERSONAL INJURY.
1.
Ensure that the Aqua-Hot has been completely shut
down and that all power supplies have been disconnect-
ed.
2.
Remove the AC access cover.
3.
If applicable, remove the heat shrink insulation covering
the wires and terminals on the defective high-limit ther-
mostat.
4.
Disconnect the defective high-limit thermostat’s Wires
from the A.C. Relay and the Electric Element.
5.
Using a 5/8 wrench or socket, remove the defective high
-limit thermostat from the Aqua-Hot’s boiler tank.
6.
Install the replacement high-limit thermostat into the
port on the Aqua-Hot’s boiler tank and finger-tighten
only (15 in/lbs).
7.
Connect the high-limit thermostat’s wires to the Aqua
Hot
8.
Secure the Thermostat Access Panel back into place.
9.
Test for proper operation.
220 °F A.C.
High Limit
Thermostat
NOTE: The location of the AC high limit thermostat may
vary in location, from Figure 12.
NOTE: One of the High Limit Thermostat’s wire will be
attached to the A.C. Relay, and the other wire will be
crimped to the wire that goes to the Electric Heating Ele-
ment.
Figure 12