Brown PVC water heater flue

[Jerry Simon]

It's the color of a brown egg. Why would this happen.

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[Marc]

Were you able to look at the inside of the pipe at the termination to observe it's color?

Marc

[Tom Raymond]

Just a WAG, but it looks like it's been cooked. Any trouble codes on the furnace? What are the chances that the exhaust could get thet hot before it shut down?

Tom

[Ben H]

Just a WAG, but it looks like it's been cooked. Any trouble codes on the furnace? What are the chances that the exhaust could get thet hot before it shut down?

Tom

Thats kinda what I was thinking. Looks like heat to me.

[Jerry Simon]

I agree, heat. This is a water heater flue, not a furnace flue. The adjacent water heater flue is fine & dandy, so weird. House is only five years old, so this happened quick. Water heaters are piped in parallel, so they run equally.

I dunno, Lucy. Need some 'splainin'

[Tom Raymond]

Got the manuals? I found American's install instructions pretty quickly online, fourth hit when I searched 'power vented water heater'. They call for 3" pipe with long sweep fittings (pdf page 9), I see 2" pipe and standard fittings. That would build up some extra heat.

http://www.americanwaterheater.com/supp ... ervent.pdf

Tom

[Jerry Simon]

Got the manuals? I found American's install instructions pretty quickly online, fourth hit when I searched 'power vented water heater'. They call for 3" pipe with long sweep fittings (pdf page 9), I see 2" pipe and standard fittings. That would build up some extra heat.

http://www.americanwaterheater.com/supp ... ervent.pdf

Tom

That sounds good, Tom. I actually mistaked the water heater flues for furnace flues 'cause of their size ('till I went in the house). I'll bet you're right.

[Bill Kibbel]

Those water heater vent systems rely on moving a large volume of air that dilutes the exhaust to reduce the temp. If it's not the size of the pipe, then it's something restricting the dilution air.

[Richard Moore]

...or maybe the power vent blower not fully functioning?

[Chad Fabry]

Mouse nest in the blower wheel? Add that to the really, really flat mouse or two and you don't move much air but probably could move enough air to satisfy the proving switch.

I think Tom's observation is excellent but it doesn't explain the one and not the other thing that's going on.

[Tom Raymond]

Ok, I'll venture another WAG. My water heater has a faulty low limit switch so the tank temp gets very close to ambient, then it fires and runs balls out to raise the temp and over shoots the high limit. A differential between the low limits from one tank to another will create a differential in run times, and a fault like mine would explain the cooked exhaust. With parallel tanks no one would notice the temp variations that I have, which led to my conclusion.

Tom

[asihi]

Jerry, what did it look like inside the house near the fan?

[Jerry Simon]

Jerry, what did it look like inside the house near the fan?

Brown, but not as pronounced. Much browner outside.