Pressure Switch Settings - State Water Heaters 60120-100250 Service Handbook

Commercial gas high efficiency water heaters

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Table Of Contents

Table of Contents

• Blower Prover Switch - normally open contacts, close on a rise in pressure.

• 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.

Activation Pressures: Pressure Switch Settings Table below shows the activation pressures and tolerance

for each of the three pressure switches. A + sign before the pressure indicates a positive pressure; above

atmospheric pressure. A - sign before the pressure indicates a negative pressure (in a vacuum); below

atmospheric pressure. Tolerances are specified to allow reasonable leeway for imperfections and inherent

variability without compromising performance.

Models

SUF 60120

SUF 100150 - 100250

SUF 119300 - 119500

Pressure Test:

1. Turn off the circuit breaker that serves the water heater.

2. Disconnect the sensing tube from the switch being tested and add a 3/16" tee to the sensing tube. Add a

short piece of sensing tube connecting the tee and the pressure switch being tested.

3. Connect a digital manometer to the open side of the tee with another piece of sensing tube.

4. 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.

5. When the Combustion Blower comes on and ramps up to full speed, record the pressure reading.

6. Repeat this test for all three pressure switches as necessary.

7. Compare the pressure readings taken to the activation pressures in the Table above.

8. Ensure all sensing tubes are properly routed and reconnected when testing is complete. The pressure

switches will not operate properly if there are leaks in the tubing. 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

Blower Prover: If the pressure reading taken at the Blower Prover switch sensing tube is at or above the

activation pressure shown in the above Table AND the switch contacts did not close during the "Continuity

Test During Operation" shown on Page 13 - the switch is defective and must be replaced. If the pressure

reading taken does not reach or rise above the activation pressure in the above Table the pressure switch IS

NOT defective and should not be replaced - call the toll free phone number on the back cover of this Service

Handbook for further technical assistance. Have the complete Model, Series and Serial number (located on

the water heater's rating label) for the water heater being serviced on hand before calling.