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I have two Luxaire furnaces in the house, same model. They both worked fine until a couple of days ago, when one of them didn't blow warm air anymore. My first thought was the igniter, so I replace it together w/the flame sensor. But comparing the two systems, they act a little different in the timing between the igniter and the gas valve.

On the good one, the igniter turns on, after abt 5 seconds the gas valve opens (I hear a click) and the burner lights up, and after another 2-3 seconds, the igniter turns off. As one would expect.

On the not so good one (the one in which I changed the igniter), the timing between the igniter and the gas valve seems to be a bit off. I see the igniter turning on, after abt 7-8 seconds, it turns off, and only after that the gas valve opens (I hear the click) and the burner ignites as the igniter still has some thermal inertia.

Is there a way to adjust the timing between the igniter and the gas valve from the control board? Or is it something else at play?

Thanks so much for any ideas, Serban.

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The timing is usually based on conditions not all ignighters are the same some get hotter quicker,.

Quit throwing parts at it.

Look up your model , error codes, I found for that brand 7 or 8 flashes flame could not be established after several attempts, 2,3 or 6 flashes pressure switch problems, 4 or 11 flashes limit switch. All of these point to different things and the timing being different can be because of the failure of a component or set point. Most units have a removable panel that when you remove it it kills power to the board. There is normally a plunger switch that can be pulled out and this is a service mode so you can see the flashes on the board when it fails. Try this to identify what is causing it not to light and get to the problem without wag (wild ass guess) now you will be troubleshooting so you move up to swag (scientific WAG).

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  • The problem is that the control board's light does not flash. I have no error codes. The burner ignites, so I guess the controller believes all's well?!? but the behavior is not right, as the igniter should not turn off before the gas valve opens. The burner ignites simply because of the igniter's thermal inertia. The new igniter seems to glow brighter than the old one, which helps, as it continues to glow, after the controller turns it off, long enough to ignite the gas. – Serban Dec 31 '20 at 5:54
  • If there are no codes the control board has failed. Some even have codes or self tests for the control or mother board but I don’t know your model number so I only posted the first few codes. The igniter color as long as hot doesn't matter I have not worked on newer furnace with electronic ignition that did not throw a code when it failed to light unless it was the control board. Water in the gas line could also be an issue 1 drop of water in the valve can prevent gas flow but again no code. So I would lean to the control or mother board. – Ed Beal Dec 31 '20 at 14:16
  • The control board is White Rodgers 50A50-230. From what I read, the 50A55-843 is a direst replacement. Considering that the burner ignites and works, I guess there are no other explanations for the behavior i see than the control board itself. Initially I was thinking that the timing between the gas valve and the igniter is influenced to other factors, like the pressure valve or other sensors, but it seems that the control board is not that sofisticated and the timing between the igniter and the gas valve appears to be hard coded into the controller. Thank you for your help. – Serban Dec 31 '20 at 17:36

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