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Propane Furnace -- Ignitor glows, pilot flame lights, but burners will not light

Propane Furnace -- Ignitor glows, pilot flame lights, but burners will not light

Old 10-30-17, 08:00 PM
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Propane Furnace -- Ignitor glows, pilot flame lights, but burners will not light

Hi everyone!

I'm new here and have a propane furnace issue I haven't been able to solve yet.

Here's some unit info. Hopefully, it's sufficient (description of symptoms follows).


HONEYWELL VALVE -- SV9541M2094 (smart valve)

PRESSURE SWITCH -- Honeywell https://www.amazon.com/1013801-Honey.../dp/B00FJCEE06

ERROR CODE: -- 6+2 Flashes (description from furnace door below):

Flame sense lost during run
Cycling pressure switch or
Blocked condensate


Turn furnace on at thermostat. Furnace blower motor engages and spins. Ignitor glows red. Pilot flame lights. Burners never light. Pilot flame and ignitor go out, tries again every 30 seconds or so for a handful of attempts. Then it blinks six flashes and then two flashes (described above).

To date, I have:
1. Swapped the flame sensor from the working furnace upstairs to the non-working furnace downstairs. No dice. Known good flame sensor, still not working. Still same symptoms.
2. Removed the furnace air filter. (no change to symptoms).
3. Blown out the condensate pipes with the power of my lungs... then shop vac sucked out the condensate line from two locations (right below the smart valve in the furnace box itself, and just after the P-trap after drain line from Heater and AC meet up. No change in symptoms.
4. Used a lighter to try to light the burners (thinking maybe the pilot flame was maladjusted. (no change)
5. Checked to make sure propane is flowing to the unit. (it is, and the same line runs to the downstairs one before going up to the upstairs furnace, and it [the upstairs furnace] is working just fine).
6. Tested the white to green wires in the distribution box where the power chord comes from the outlet into the furnace box and splits off to the various parts of the furnace. Reads .012. Had a furnace person tell me that the reading was showing a bad ground somewhere, and that was causing issues with the flame sensor. The problem I see with that is that the upstairs furnace has a reading even worse (like .030, or something like that), and it has no problems starting.

I'm beyond my skill here. I'm guessing the issue is either the pressure switch or the valve, but I really don't know, and the company we have around here that I'd call to come help isn't a company I trust (they've already missed gas leaks that they themselves caused with improper installation, or something). Anyway, y'all's help would be much appreciated. Thanks, so much!

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