High-Limit Thermostats
©Aqua-Hot®
250-D03 Diesel Series Service Manual
REV 220302
p. 25
Replacement Procedure:
If it has been determined that the AC high-limit thermostat
needs to be replaced, it can be easily replaced by following the
directions below.
1. Shut off gas, electric, and water supply to the Aqua-Hot.
2.
Disconnect the domestic water inlet and outlet line fittings
from the Aqua-Hot.
3.
Unscrew the nut that affixes the mixing valve to the left side
of the Aqua-Hot cabinet wall.
4. Push down on the mixing valve to expose access to the AC
high-limit thermostat.
5. Cut the wire tie which wraps the wires on the left side of
the unit.
6. Cut the black wires on the AC high-limit thermostat as close
as possible to the body of the thermostat and strip the
other end.
7.
Remove the faulty high-limit thermostat using a ⅝” socket
or crow’s foot.
8. Butt-splice a new AC high-limit thermostat to the stripped
wire.
9.
Reinstall the AC high-limit thermostat using a ⅝” socket or
crow’s foot.
10. Re-secure the wires (AOT1 & AOT2) using the extra wire tie
provided and reinstall the mixing valve assembly.
11. Make sure the replacement AC high-limit thermostat is
functioning properly by testing for continuity across this
thermostat.
12. Reposition the tempering valve assembly onto its mounting
stud on the left cabinet wall.
13. Re-secure the tempering valve assembly with the previously
removed nut.
14. Reconnect the domestic water connections to the PEX
fittings of the tempering valve assembly.
15. Reestablish the gas, electric, and water supply to the Aqua-
Hot.
16. Test for unit for normal operation.
Unscrew this nut
Figure 39
Figure 40
