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Old 03-02-2008, 05:27 PM   #1
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soot in heat ex


i have a goodman hi eff hot air upflow furnace.the haet exchangers are starting to clog w/black soot.air flow is limited &causing overheat sensors to trip.have dissembled burners &ex blower&cover for lower part of exchanger.it was full of soot &water on center&far r/side ports,have cleaned out as best as possible,flames look good always runs w/out shuting down.i had the same problem w/previous furnace which was a +90 whoorlpool unit.Any ideas? ps runs on lp


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Old 03-02-2008, 06:13 PM   #2
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soot in heat ex


Have you checked the outlet pressure from the gas valve?

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Old 03-02-2008, 06:21 PM   #3
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The sooting of the heat exchangers are hard to clean on the 90 plus furnaces, because of the condensing coil just above the blower, my advise is to replace the whole exchanger then have the outlet pressure checked with a manometer.
The exchanger should be under warranty
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Old 03-02-2008, 06:40 PM   #4
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soot in heat ex


Are you using propane?
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Old 03-02-2008, 08:43 PM   #5
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Are you using propane?
yes,also exaust smell is very strong
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Old 03-02-2008, 08:47 PM   #6
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What is the outlet pressure on the gas valve?
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Old 03-02-2008, 08:49 PM   #7
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soot in heat ex


Can you see any LP stickers to know, that it has been converted from natural to LP gas.
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Old 03-02-2008, 09:07 PM   #8
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Can you see any LP stickers to know, that it has been converted from natural to LP gas.
definitly lp i bought ,installed&converted it myself,as far i know the gas pressure is good,i dont have any way of ck ing it but flames are strong & blue
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Old 03-02-2008, 09:24 PM   #9
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definitly lp i bought ,installed&converted it myself,as far i know the gas pressure is good,i dont have any way of ck ing it but flames are strong & blue
The sooting means incomplete combustion, either it is not burning right, or the gas pressure is not set right, it should be 11" water column. If the vent was stopped up the pressure switch would not let the unit run. Have you ever ran out of propane?
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Old 03-03-2008, 06:16 PM   #10
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No have never ran out of propane.
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Old 03-03-2008, 06:27 PM   #11
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No have never ran out of propane.
When, after it was installed did it start sooting? Have you checked the vent intake for anything that might have gotten in it, and blocked it? I have seen wasps build nests in them and birds like to fly in them and then not be able to turn around once in and die?
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Old 03-03-2008, 10:01 PM   #12
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soot in heat ex


what size of orfice do you have on your manifold. It should say on the bar going along the burners. If it is oversized or undersized it will soot up. If not that then you will have to pull the heat exchanger and usually you will find a couple of pin holes. Good Luck with the Goodman dealers on warranty
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Old 03-04-2008, 08:55 AM   #13
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The sooting of the heat exchangers are hard to clean on the 90 plus furnaces, because of the condensing coil just above the blower, my advise is to replace the whole exchanger then have the outlet pressure checked with a manometer.
The exchanger should be under warranty
How can you warranty somthing that is not the furnaces fault? It sounds like the owners fault because he never adjusted the gas pressure after conversion. We all know that that needs to be done.
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Old 03-04-2008, 02:59 PM   #14
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How can you warranty somthing that is not the furnaces fault? It sounds like the owners fault because he never adjusted the gas pressure after conversion. We all know that that needs to be done.
Thats true

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