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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22678
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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I have a Heil gas furnace with a Honeywell SV9541 gas valve,

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I have a Heil gas furnace with a Honeywell SV9541 gas valve, and a Honeywell ST9120U1011 control board. When call for heat turns on, the inducer blower will not start. The pressure sensor is confirmed opened, and voltage is present on the two lines from the control board to C3 (gas valve), but no voltage from C3 to the blower. If I jump the pressure sensor and then un-jump it, the inducer blower will turn on. If I then reconnect the pressure sensor (within 30 seconds) the pilot will fire, burners will fire, and furnace will run. So it appears the pressure sensor has to be closed before the induction motor will start. Then go opened and closed again for the furnace to start. Could this be a defective gas valve or could it be the control board?

My name is Billy.

This is the curse of the Smart Valve.

This series was prone to failure and erratic inducer operation is the main fault.

You will need to change the gas valve.
And they are not cheap.


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