New Goodman 95% 90K Propane Conversion NOx Yellow Flame

[Shanata]

I have a new Goodman 95% two-stage furnace model number GCH950904CXAE (Low NOx) that has been converted to propane. I was working with a licensed technician. The conversion springs (red), orifices (#55), inlet pressure (11.5), and manifold pressures (6,10) have all been verified. The burn is wrong. Flames turn from blue to all yellow in seconds and there is too much condensation. The induction fan is filling with water. Taking the door off, removing the inlet, and shortening the flue – no change. The technician had me replace all my 2.5 inch pipe to 3 inch even though I was under (just barely) the limit for 2 inch, so the tech had me upgrade to 3 inch. No change. Blow lightly into any tube - blue flame. I questioned the heat exchanger cover hole size. Goodman wouldn’t talk to me, but dealer was told hole was 15/16 for 90K, 3/4 for 70K. Mine was between the two at 22mm, so I was sent a replacement. It was also 22mm. So my question now is the with the propane conversion and NOx. The dealer said my unit does not have NOx screens. My technician didn’t find any screens. So I found this post http://hvac-talk.com/vbb/showthread....conversion+nox which mentions Goodman added turbulators around 2010. Other companies in their LP conversion talk about removing the turbulators or adding propane spoiler screws. The Goodman LP instructions, dated 9/2013 make no mention of either. Any suggestions of what else to look for?

[dougfamous]

Look for a professional to come in and set it up properly. Propane is not something for a DIYer to play around with, and it already seems like you're set up wrong. Get a pro in before you do some serious damage to that furnace (if you haven't already).

[Shanata]

As I said I was working with a technician. He is from a local HVAC company that installs and repairs. He couldn't find anything wrong and had me redo all my vents. The install and set up are good. I haven't run the furnace except for the blower, living off of the wood stove and tearing my house apart at temps down to -17 degrees. Goodman doesn't cover labor only parts. Before he is out again, I trying to eliminate possibilities. Both he and the dealer are down to there is something wrong with the furnace. That's why we were trying to get info of the heat exchanger front cover. It was something to check before tearing the heat exchanger apart.

[dougfamous]

Again, if the dealer you're using can't solve this it's time to get someone more experienced with LP to look at it. You absolutely should not be doing any of this yourself. Did you purchase this furnace off the internet? Are you aware that Goodman doesn't warranty parts if you did?

[Jim Davis]

Without a combustion analysis it is hard to diagnose any problem. Flame color has no bearing as far as clean or dirty. Yellow can be clean and blue can be dirty. Need a CO test!! O2 and Flue temperature are also necessary. 90% of contractors that service and sell equipment don't use one or know how to use one.

LP units should have no NOX screens or baffles in them. In any state other than California they shouldn't even be there. They cause the equipment to burn poorly and inefficient. Somehow the government would rather us make CO than NO.

[second opinion]

Without a combustion analysis it is hard to diagnose any problem. Flame color has no bearing as far as clean or dirty. Yellow can be clean and blue can be dirty. Need a CO test!! O2 and Flue temperature are also necessary. 90% of contractors that service and sell equipment don't use one or know how to use one.

LP units should have no NOX screens or baffles in them. In any state other than California they shouldn't even be there. They cause the equipment to burn poorly and inefficient. Somehow the government would rather us make CO than NO.

I would agree visual does not do much unless you are looking for dust, lint rust etc.

[wahoo]

In our state (Mo.) the technician has to be licensed to perform any work on a propane fired furnace. So make sure and get a certified tech. and have them perform all the test. I'd also recommend an actual Goodman dealer so you don't have any warranty problems. Unless you've actually purchased this yourself over the internet, in which case you've already got problems. A 90K furnace is a pretty large model, so I assume you've had a heat loss computation done? As mentioned I've not seen any turbulators for years however they caused a lot of problems. Simple dust into a gas flame will give you orange fire! But all yellow is something else entirely. How about some pictures of this installation?? What are the CO readings at the flue?

[HVAC_Marc]

Simple exhaust gas recycling will cause yellow flames.

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