Corrosion in natural draft furnace

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Originally Posted By: jwortham
This post was automatically imported from our archived forum.

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Did another in a never ending series of practice inspections yesterday.


While checking out the furnace, I noticed corrosion up inside the dilution air intake.


Since I am new to the profession, wanted some other opinions. Is this telling me they may have a drafting problem that's allowing corrosive exhaust to vent back into house? Or do they all look like this?

Thanks for any help. SOOOOO much stuff to learn! 

[ Image: http://www.nachi.org/bbsystem/usrimages/more/looking%20up%20into%20dilution%20air%20intake2.JPG ]

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[system]

Originally Posted By: jpope
This post was automatically imported from our archived forum.

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This doesn’t look excessive to me. How old is the furnace? Did you do the standard “mirror” test?

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Jeff Pope


JPI Home Inspection Service


“At JPI, we’ll help you look better”


(661) 212-0738

[system]

Originally Posted By: jwortham
This post was automatically imported from our archived forum.

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Furnace is approx. 15 yrs. old.


And WHAT is the standard mirror test? (As you can tell, I obviously didn't do it since I don't know what it is!)

Thanks.

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[system]

Originally Posted By: jpope
This post was automatically imported from our archived forum.

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While the furnace is operating, hold a mirror below the area in your picture, and just below the exhaust exiting the furnace. If your mirror fogs up, the unit may not be venting properly.


The same moisture that fogs the mirror, is the cause of the corrosion in your picture.

Being a 15 year old furnace, I would say it's probably okay. The overall condition of the unit is better evaluated by much more than that small amount of corrosion.

Always check the joints of the exhaust vent and the dilution entrance for corrosion to get a clearer indication of potential problems.

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--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738