Fauty Flame Rod???

Terry_21

Hello all:

I have a Goodman GMP075 furnace. For some reason the furnace runs great most of the winter and then burners will drop out a minute or so after ignition. I install a new flame rod and it works OK again however the latest flame rod only lasted a month. It's not any of the other safeties causing the recycling problem nor the induced fan pressure switch.

Any thoughts on what else might be causing this problem?

tia

Terry

Darrell

Good chassis grounding is critical...dry, dusty, vibrating, and dis-similar metal environments all combine to make the grounding over time a difficult thing. Make sure the flame rod is positioned perfectly according to spec. The gas flame/proving rod just barely works by design, which makes it inherently very safe...but, it's gotta be just right. Make sure it is clean too...dust, sulphur, mercaptan all precipitate onto the rod and insulate it. Sometimes the rod needs cleaned very often if the air is dirty.

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Unknown

What are

your Microamp readings on the flame rod? Flame rods are pretty dependable and other than cleaning do not have many problems. As some one else mentioned grounding is critical for the system and sometime the electronic board can be erratic. What is the make of the board on the unit and the numbers?

jim lockard

Where is the furnace

Laundry room, woodworking shop? Any renovations going on in the home? Was the flame sensor carbonized?(all black on rod) if so it could be in the air your furnace is breathing? J. Lockard

allan_7

You might want to check the pressure switch or the vent connector and the auxiliary overtemp limit.

Check the wiring schematic on the door or website.

You will notice the p/s is shown in two circuits.
It is shown as a logic circuit and also in series with the W heat call. It is hardwired with two leads but the other circuit is in the board tracings (I think).

Connect your volt meter to it and watch the voltage.

There is also an auxiliary limit in series with gas control that is out of the logic circuit of the IFC.

If push comes to shove, get a piece of plexiglass to seal the blower compartment and see what the red LED does.

Had a GMC that was tough to figure out.

Life gives you the test first and then the lesson.....

allan_7

You might want to check the pressure switch or the vent connector and the auxiliary overtemp limit.

Check the wiring schematic on the door or website.

You will notice the p/s is shown in two circuits.
It is shown as a logic circuit and also in series with the W heat call. It is hardwired with two leads but the other circuit is in the board tracings (I think).

Connect your volt meter to it and watch the voltage.

There is also an auxiliary limit in series with gas control that is out of the logic circuit of the IFC.

If push comes to shove, get a piece of plexiglass to seal the blower compartment and see what the red LED does.

Had a GMC that was tough to figure out.

Life gives you the test first and then the lesson.....

allan_7

GMC Furnace

You might want to check the pressure switch or the vent connector and the auxiliary overtemp limit.

Check the wiring schematic on the door or website.

You will notice the p/s is shown in two circuits.
It is shown as a logic circuit and also in series with the W heat call. It is hardwired with two leads but the other circuit is in the board tracings (I think).

Connect your volt meter to it and watch the voltage.

There is also an auxiliary limit in series with gas control that is out of the logic circuit of the IFC.

If push comes to shove, get a piece of plexiglass to seal the blower compartment and see what the red LED does.

Had a GMC that was tough to figure out.

Life gives you the test first and then the lesson.....

Glenn_16

As others have said, grounding is key. Remember too that that flame sensor is sending a signal to the burner. You may want to sand at least that part of the burner that completes the signal path and if you can, find a way to be sure that burner itself has a good ground.

Don't assume that the ground path from the burner to ground is good.

Brian_24

The problem is the draft inducer shuts off too soon leaving the heat exchanger full of moisture. This is what is ruining your flame sensor. I have added post purge timers and this stops the trouble.

PARTSMAN

goodman furnace

We had the same problem some years ago. After trying everything,we found lint and dust had built up in the burner that fires across the flame sensor. After removing the burner and washing it out (mfg. rec.) the furnace ran fine. Now every year we do a tune up we make sure that the burner is cleaned very carefully. The homeowner even knows how to clean it.