Continuity Test During Operation; Pressure Test During Operation - State Water Heaters SUF 119300 Service Handbook

CONTINUITY TEST DURING OPERATION

This test is performed while the Combustion Blower is running at high speed during the Pre-Purge operating
state. The test is performed on all three pressure switches. Disconnect the two wires to each pressure switch
- one at a time, check continuity and then reconnect the wires to that switch before testing the next switch.
1. Turn off the circuit breaker that serves the water heater or unplug the water heater appliance cord from
the 120 VAC wall outlet if so equipped.
2. Ensure the sensing tubes from each pressure switch are connected to the correct sensing port on the water heater.
3. Disconnect the two wires for the switch to be tested.
4. When testing the Blocked Exhaust and Blocked Air Intake Switches, connect a jumper wire between the
two wires disconnected. This will temporarily prevent the Control System from locking out during the test.
When the test for these two switches is complete, remove the jumper wire and reconnect the pressure
switch wiring before moving on to the next switch.
5. Restore power to the water heater, if the water heater does not begin a heating cycle raise the Operating
Set Point to activate a heating cycle.
6. Using an ohm meter set for continuity testing, check for continuity between the two wiring terminals at the
pressure switch after the Combustion Blower has started and ramped up to high speed during the Pre-
Purge operating state. Record the results; open or closed.
7. Repeat this procedure for each pressure switch.
8. Turn off the circuit breaker that serves the water heater or unplug the water heater appliance cord from
the 120 VAC wall outlet if so equipped. Confirm that all of the pressure switch wires are reconnected
including the replacement part if necessary based on the Results/Actions listed below. Restore the
electrical power to the water heater. Reset the Operating Temperature Set Point if it was adjusted. Run
the water heater through a complete heating cycle before leaving to ensure it is operating properly. Draw
water from the nearest faucet to make sure that the water temperature does not pose a scalding hazard
due to the increased temperature set points that were used in this procedure.
Results/Actions
Passed Results: If the Blocked Air Intake Switch and Blocked Exhaust Switch contacts remain closed during
this test, (zero ohms/direct short), these switches have passed the test.
Failed Results: If the Blocked Air Intake Switch or Blocked Exhaust switch contacts open during this test, the
Pressure Test During Operation below must be performed to determine if the switch(s) is defective. Proceed
to the Pressure Test During Operation below.

PRESSURE TEST DURING OPERATION

This test will be performed while the Combustion Blower is running at high speed during the Pre-Purge
operating state. This test is necessary when a pressure switch has passed the "Continuity Test During Standby"
shown on Page 13 but has failed the Continuity Test During Operation above to determine if the pressure
switch is defective or not. This test requires a digital manometer, see "Tools Recommended" on Page 3.
Service Notes:
• Before performing this test examine the sensing tube connections on the water heater's sensing ports
and on the pressure switch. Check for wear, cracks, leaks, kinks, or any kind of debris or condensate in
the sensing tubes, repair/replace as necessary.
• To determine if a pressure switch is operating properly you must first know the "switch action" (whether the
switch activates on a rise or a fall in pressure) and the "activation pressure" the switch will activate at. Activation
pressures are provided in "Pressure Switch Settings" Table on Page 15. Switch actions are as follows:
• Blocked Air Intake Switch - normally closed contacts, open on a fall in pressure.
• Blocked Exhaust Switch - normally closed contacts, open on a rise in pressure.
14 Servicing should only be performed by a Qualified Service Technician