Rust inside 2004 furnace

Jeff Eastman · 07-26-2007, 04:41 PM

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**Phillip Stojanik** · 07-26-2007, 04:50 PM

Originally Posted by Jeff Eastman

Ideas on what is causing the rust inside of this furnace?

Moisture?

**Scott Patterson** · 07-26-2007, 04:51 PM

Moisture!

**Scott Patterson** · 07-26-2007, 04:52 PM

Well it looks like Phillip and I are on the same page!

**Phillip Stojanik** · 07-26-2007, 04:52 PM

Originally Posted by Scott Patterson

Moisture!

Great minds think alike eh Scott?

**DavidR** · 07-26-2007, 05:06 PM

Was that the only spot in the furnace showing any signs of rust?

Richard Rushing · 07-26-2007, 05:14 PM

My first thoughts are, two:
1) There obviously could be moisture running down the flue.
2) The moisture could be created by a short purge-cycle that doesen't allow for the hot combustion fumes to exit out thru the roof. The result would be the cold air in the attic would cause condensation to form on the outside and drip back down.

Or, there could have been a circus in town that had a monkey escape. The monkey climbed the roof and urinated down the chimney...

**Scott Patterson** · 07-26-2007, 05:21 PM

I would vote on condensation down the flue pipe. But this is only a guess. This is one of the camels that folks strain on but watch out for the gnats they will choke you!

This would not even make my report.

**wayne soper** · 07-26-2007, 05:57 PM

I agree, condensation between cycles.

**DavidR** · 07-27-2007, 03:06 PM

Originally Posted by Scott Patterson

I would vote on condensation down the flue pipe. But this is only a guess. This is one of the camels that folks strain on but watch out for the gnats they will choke you!

This would not even make my report.

Scott if you run up on this it needs to make a report if it's from the flue gases as it is a defect, flues are not meant to condense on the inside unless it's a condensing furnace.

There are ways to fix these condensation issues that require the addition of a post purge circuit.

**Scott Patterson** · 07-27-2007, 04:31 PM

Originally Posted by DavidR

Scott if you run up on this it needs to make a report if it's from the flue gases as it is a defect, flues are not meant to condense on the inside unless it's a condensing furnace.

There are ways to fix these condensation issues that require the addition of a post purge circuit.

Could be, but this IMO is way outside the scope of a home inspectors job. Now, if you have an HVAC background and you see this as a problem you will not agree with my philosophy. Chances are that the small amount of rust stains were just one of several other signs that one could see if we had an entire picture of the flue pipe, etc.

Based on that picture, I do not see it as a problem and truth be known I don't know if I would have even seen it unless there were some other signs.