Nordyne RK80+ Downflow

[kipperps28]

The furnace will turn on the blower, then igniter will glow red, but none of the burners will fire. Red light is blinking 4 (ignition failure). All grounds look good. Red light is also on solid when furnace is commanded on. Unit is under warranty (6 months old) but it is Sunday, and can't get ahold of warranty Co. Any help would be appreciated.

[Scottthewolf]

You probably have a weak hot surface glowbar ignitor, just because it glows red does not mean it is working correctly.  The ignitor shouuld glow bright orange/almost white, if not, it probably isn't getting hot enough or drawing enough amperage to make the gas valve open.

[hvacdrd]

Check the basics too - is the gas on? Do your other gas appliances work?

[kipperps28]

Yes, gas is on (hot water heater is next to furnace, and line T's off of same supply (water heater is working). The info on the igniter is interesting. Is there an ohm spec on the igniter, or do you just swap in a "known" good one? Thanks for the help, guys! BTW, the igniter does actually glow orange, though not at all white. I will have a call into my warranty Co tomorrow, if I don't figure it out myself. I will post the cause when I know.

[AccApp]

Is the control board sending voltage to the gas valve after the ignitor glows? The gas valve is not dependant upon amp draw from the ignitor but is a timed sequence. Are you certain the burner does not light at all?

[kipperps28]

Yes, I am sure. There are 4 burners, and my understanding is they fire in a linear fashion, with the left side (flame sensor) burner being the last in line. None of the four fire. I have not tested for power at the gas valve. There is one yellow wire and one brown wire (these originate at the circuit board). I would assume only one of these would provide power for the valve...

[AccApp]

Check the valve's coil for resistance by removing the brown and yellow wires. If it is open electrically we know the gas valve is bad. You can measure the voltage to the gas valve by leaving the brown and yellow wires removed and checking the voltage between them after the ignitor has been glowing at least 30 seconds. Expect it to be around 24 vac.

[kipperps28]

Repair guy came out this morning and replaced the gas valve with a new one. Works like a charm. Thanks for the help!