Dc High-Limit Thermostat (Right) - Aqua-Hot 400 Series Service Manual

Burner High-Limit Thermostat (Right):
The Burner High-Limit Thermostats serve as a safety meas-
ure in the event that the burner continues to operate after
the maximum operating temperature is reached. The high-
limit thermostats allow the current for the burner to pass
through them until the boiler tank reaches a temperature of
215°F. Should this temperature be reached, the high-limit
thermostat blocks the current to the burner's gas valve,
which prevents the burner from operating.
Troubleshoot the Right Burner High-Limit Thermostat, Wires
33 & 36, if the following condition has occurred:
 The Gas Valve on the burner fails to operate.
 The Blower Fan runs, but burner does not ignite.
Troubleshooting:
1. Locate the Right High Limit Thermostat, Wires 33 & 36.
Disconnect the wires from the thermostat and place a
jumper wire between the two wires to bypass the high
limit thermostat. Check the Aqua-Hot for normal opera-
tion.
NOTE: By passing the high-limit thermostats is for testing
only and must not be used for the Aqua-Hot's normal func-
tionality.
2. Disconnect the DC high-limit thermostats' wires, then,
using an ohmmeter, check each thermostat for continu-
ity.
If there is no continuity, complete the following:
A. Press the white reset button on the high-limit ther-
mostat, then re-check for continuity.
Figure 14
Thermostat
215°F
High Limit
If a thermostat, with the wires removed, that has been reset
does not have continuity, follow the instructions in this sec-
tion to replace the high-limit thermostat.
If an individual wire does not have continuity, that wire must
be replaced.
NOTE: If the high-limit thermostats continue to trip, trouble-
shoot the control thermostat and verify the boiler tank is
full of antifreeze and water heating solution.
Replacement Procedure:
F
AILURE TO DISCONNECT ALL POWER SUPPLIES AND
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 sources have been disconnect-
ed.
2. Remove the two wires from the defective high-limit ther-
mostat by pulling firmly on the wires.
3. Using a 5/8 wrench or socket, remove the defective
high-limit thermostat from the Aqua-Hot's boiler tank.
4. Install the replacement high-limit thermostat into the
port on the Aqua-Hot's boiler tank and finger-tighten
only (15 in/lbs).
5. Connect the wires removed from the defective high-limit
thermostat to the replacement high-limit thermostat.
6. Test for proper operation
© Aqua-Hot® AHE-400-P01 Service Manual Rev.B June 2014
Section #: Title
Aqua-Hot Components
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OR TO ALLOW THE
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