Reznor SDH Series User Manual (English)

Questions and Answers:

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Amanda MoranAug 10, 2025
How to troubleshoot Reznor SDH Air Handlers venter motor that won't start?
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  Steve WongAug 11, 2025
  If the venter motor in your Reznor Air Handlers unit isn't starting, several issues could be at play. First, ensure the unit has power by checking the supply fuses or circuit breaker. Then, verify power is reaching the venter motor by examining connections at the burner relay and/or venter motor terminals. If those are fine, the integrated burner relay or the venter motor itself might be defective and need replacement. Also, check if fuse (F3.1) or fuse burner relay are blown and replace them if needed. Try resetting LC3 or pushing the reset button. Lastly, make sure the thermostat is set above room temperature.
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cookjoannaAug 16, 2025
What to do if Reznor Air Handlers burner will not light?
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  James PatrickAug 16, 2025
  If the burner in your Reznor Air Handlers isn't lighting, start by checking the voltage on the main valve during the ignition period and inspect the connectors on both the main gas valve and burner relay. Ensure all wire connections are solid and maintain a 3 mm spark gap. If the spark cable is shorted or the ceramic spark electrode is cracked, replace them. Verify the burner relay and the unit are properly grounded (earthed) and phased (L1 to hot lead, L2 to neutral). If voltage is available to the burner relay and all other causes have been eliminated, replace it. Also, confirm the unit is properly vented, remove any obstructions, and replace any faulty tubing or the pressure switch related to the combustion air pressure switch.
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Jessica GonzalesAug 22, 2025
Why does Reznor SDH burner cycle on and off?
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  Jared SnyderAug 23, 2025
  If the burner in your Reznor Air Handlers cycles on and off, ensure the gas supply pressure is correct: 15 mbar for natural gas (UK only) or 37 mbar for propane gas. Check the burner relay ground wire connection. If (220/240) volts is available to the burner relay and all other causes have been eliminated, replace it. Make sure the flame sensor lead isn't grounded, and the insulation or ceramic isn't cracked; replace as needed. If the ceramic at the sensor is cracked, replace the sensor. Verify and correct the polarity by reversing line voltage wires to terminal block connections if necessary.
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Veronica MitchellAug 28, 2025
How to fix Reznor SDH fan motor that will not run?
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  Chase HurstAug 28, 2025
  If the fan motor in your Reznor Air Handlers won't run, check the wiring and connections for any open circuits. If the wiring is intact, the fan time delay relay may be defective and require replacement. If the issue persists, the motor itself may be defective, necessitating replacement of the blower and motor.
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deborahelliottSep 4, 2025
Why does Reznor SDH Air Handlers fan or venter motor turns on and off during burner operation?
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  Terri ThomasSep 4, 2025
  If the fan or venter motor in your Reznor Air Handlers turns on and off while the burner is operating, the motor's internal thermal protection device may be cycling. Check the motor load against the motor rating plate, and replace the motor if needed.