A.O. Smith DSE-5, Руководство по обслуживанию

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Servicing should only be performed by a Qualified Service Agent
29
OPERATION & SERVICE
Heating Element Resistance & Ground Tests
This is a two part test. In the first test the actual resistance (ohms) of each heating element loop is
measured. In the second part of this test each heating element loop is tested for any continuity to
ground to ensure the heating element is not shorted to ground. These tests should be considered as
third and fourth diagnostic procedures to be performed whenever the results from the Heating
Element Amperage Test showed a heating element was not drawing the correct amps AND the
results from the Heating Element Voltage Test showed the element had the proper voltage applied.
Measuring Resistance
1 Determine what the actual voltage and KW rating is for the heating elements in the water heater being
serviced - see Heating Element Ratings on page 23. Ensure the voltage and KW rating of those heating
elements are the correct ratings for the water heater being serviced - see the rating label on the water
heater. Replace any elements that are not the proper rating for the water heater being serviced before
proceeding.
2 Secure power to the water heater at the main breaker or disconnect switch.
3 Verify with an AC volt meter that there is not any voltage present at the Power Distribution Block (see
Figure 2 on page 9) or the contactor on single element models.
4 Disconnect and label the power wires from the contactor(s) to all elements being tested. Pay close
attention to wiring and which heating element loops (see pages 16 & 17) connect to which terminals on the
contactor(s). Use wire markers (see Tools Required page 3) to label contactor terminals and/or the wiring
leads of the heating element to ensure they are reconnected properly when finished.
5 Using an ohm meter: set the ohm meter to a range just above the expected ohms (200 ohm range initially).
Six Wire Elements: Measure and record the resistance (ohms) between the two wire ends from each loop
on the heating element - three ohm readings. Note the pattern the three loops form on the heating element
flange on a six wire element as shown in the illustrations on pages 16 and 17. Ensure you are not
measuring the resistance of the same loop more than once. Ensure you are not measuring resistance
between wires from two separate loops. The three ohm readings should be approximately the same.
Three Wire Elements: Measure and record the resistance (ohms) between each wire end of the heating
element and the metal bar that shorts/spices together one end of each heating element loop on a three
wire element - three ohm readings. See the illustrations on pages 16 and 17. The three ohm readings
should be approximately the same.
Compare the measured ohms values to the values given in the Heating Element Resistance tables on
page 28 for the correct type (six or three wire) element being tested.
If the resistance reading for any element/loop is infinite (no continuity) - the heating element is defective
and must be replaced - see page 31.
See additional images, illustrations and
information in the Heating Element Construction
and the Six and Three Wire Heating Elements
sections on pages 16 and 17.
3 Wire Element Resistance Test 6 Wire Element Resistance Test