Gas furnace, digital tester... No voltage on the secondary

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georgestolz said:
...I'll betcha 24VAC would look like about 11VDC...
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Why would you bet that? I thought the RMS value was the equivalent DC voltage that would produce the same power as the ac voltage. Since the wave is positive and negative instead of some 1/2 wave rectified signal, why would you guess 11 VDC? Why not just zero, except for some minor DC offset? Just asking.
 
It could also be an interlock circuit like the gas pressure switch (and even air in the line being a new install) or the micro on the sheetmetal cover or a poor connection or cross connection in the thermostat too.

LOTS of things can keep a gas burner control circuit from closing.
 
is this a residential gas furnace?

is this a residential gas furnace?

you should be able to read the secondary voltage of 24 vac at the xfmr. if you are not reading the 24vac at the sec, most likely you have a bad xfmr

if your xfmr tests ok, i would trace the 24vac hot wire thru the wiring and look for continuity thru the switches,



possible the i/o board is bad .
 
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