If the water is coming from a known source (such as a relief valve), repair or replace
the valve. Route the discharge piping to a drain or sump to keep the floor dry.
Leaking tank fittings must be replaced to protect the tank, insulation and other
mechanical room components.
Dielectric fittings (with plastic linings) must be replaced with identical units. A less-
desirable alternative is to replace them with galvanized steel nipples and dielectric
Replace all piping insulation right up to the tank jacket after repairing fittings.
Sensor wires are sometimes run between the tank wall and the insulation, where the
temperatures occasionally rise high enough to damage the wire insulation. Replace
these with new wiring run between the insulation and the outer jacket, or neatly
routed outside the jacket.
Some tanks use an electric element in the top of the tank as a back-up heat source.
If the sensor wiring is near the 240V electrical supply, the element or the thermostat,
move it to at least 2 feet away from the 240V equipment.
All storage tanks have one sensor near the bottom, used by the system control for
normal on-off operation. Another sensor may be installed near the top or outlet for
high limit control.
If threaded studs or clips are on the tank, use them to secure the sensor to the tank
If there is no stud or clip, the high limit sensor may be clamped to the outlet pipe.
This is the pipe leading to the load or back-up system. Use a stainless steel hose
clamp, and tighten it enough to hold the sensor in good thermal contact, but not
crush it (Figure 5-34).
The lower sensor, used for sensing tank temperature for differential operation must
not be clamped to an outlet pipe if dip tubes are used. In this case, remove a
section of tank insulation near the bottom of the tank.
5.2 REPAIR PROCEDURES