Trane XE 90


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Old 02-24-10, 05:13 AM
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Trane XE 90

I have the above model that runs on propane that is power vented. This morning while the house was still quite I could tell the furnace didn't go through its normal start up. Normally the vent fan comes on and in about 10 seconds the furnace ignites and about 30 seconds later the circulation fan kicks in.

This morning I heard the vent fan turn on and the ignition but before the circulation fan came on it shut down. After about 30 seconds the process starts over and this time the circulation fan comes on but I am sure its because of the heat that is already there. I go downstairs to investigate and I watch it when it starts again and notice that the flame is acting like it is being told to shut off, not just going out. I also notice the vent fan/motor is making a funny noise.

I first think the vent fan motor is toast, it kinda sounds like it could be the bearings/bushing gone out in the thing. I then notice the drain hose coming off the bottom of the fan housing and that it is black with gunk. I remove this hose from the fan housing and about a 1/4 cup of water pours out of the housing. I blow through the tube and pour water down it to make sure the tube is open, it is. The sump pump comes on and all that.

I replace the tube and everything appears back to normal. No noise from the fan, which was evidently water being hit by the fan blades and limiting the air flow which was shutting down the burners.

My question is this. Is that all there is? Do I need to look at/for something else? The unit is pushing 14 years old and has never given me one bit of trouble till this morning.

Thanks.
 
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Old 02-24-10, 07:18 AM
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Originally Posted by oneshotman
I then notice the drain hose coming off the bottom of the fan housing and that it is black with gunk. I remove this hose from the fan housing and about a 1/4 cup of water pours out of the housing. I blow through the tube and pour water down it to make sure the tube is open, it is. The sump pump comes on and all that.

I replace the tube and everything appears back to normal. No noise from the fan, which was evidently water being hit by the fan blades and limiting the air flow which was shutting down the burners.


Yes, you have very likely identified the cause of the problem. Condensing furnaces can develope a problem with mold growing on the wet, moist parts of the furnace and this can plug up the drainage system, just as you describe.

You probably need to open up the burner compartment and do a more thorough job of cleaning and flushing the mold out of the system.

Take the plastic drain hose off and flush that out with water until the system is clean. Remove the inducer motor which will provide access to more of the heat exchanger system and use a hose and nozzle to flush out that system until the water runs clean.
 
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Old 02-24-10, 12:58 PM
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Thanks for the feedback. I will do as you suggested. I did notice the drain line coming out of the heat exchanger was not black with crud like the one coming off the fan housing but I am sure it could use with a cleaning too.
 
 

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