Furnace heat cycle

If you're talking about the heat sensor in 5.), I don't understand.

The inducer runs it's little cycle, the igniter glows. It *sounds* like the gas valve opens, but the burners don't fire.

You're saying maybe the heat sensor has crud from previous cycles and shuts the gas valve down before the burners have a chance to fire???

The burners don't fire and then shut down prematurely. They fail to fire at all.

"Take Yo' Hand Out My Pocket (I Ain't Got Nothing What Belongs To You)!" - Rice Miller, who probably never even _heard_ of GW Bush, Paulson, etc

Common problem. Clean the flame sensor with emery cloth. When flame comes on sensor generates very small amount of current which is sensed by control board logic.

I wish I had this in my back pocket 3 weeks ago when I had to call in a Sunday tech to do the exact same thing for $110 instead of me doing it, for a lot less!

Thanks for the great advice, Rich

The gas valve may be sticking, making a clunk, but not actually opening.

When inducer motor comes upto speed pressure switch should trigger next is ignitor coming on(if it's not spark type, it should glow bright) then valve opens, gas ignites, flame sensed, blower comes on. What model furnace? No trouble code?

I refrain from relating additional info to Mr. Tony as there is evidence that it might further confuse him. :-)

"Take Yo' Hand Out My Pocket (I Ain't Got Nothing What Belongs To You)!" - Rice Miller, who probably never even _heard_ of GW Bush, Paulson, etc

Take the safety stuff off, go outside and throw it as far as you can.

If the inducer was the problem, it should not get to the igniter stage. I'm wondering if the igniter isn't drawing enough amps to satisfy the board.