Smoke Stain at TPR Valve connection

[Erby]

What causes the smoke stain at the TPRV connection?

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[David Meiland]

Are those gas units? Are they in unconditioned space?

[Marc]

Maybe the plumber got the pieces too hot when he sweated the connections. Smoldered the insulation.

Marc

[Erby]

Nah, electric about 7 years old in the hall closet with the heat pump.

[Jim Katen]

What causes the smoke stain at the TPRV connection?. . .

The same thing that causes it above light fixtures, convective air currents.

The TPR is warm. It warms the air around it, causing that air to rise in a small stream. If there's dirt in the air, it stains the surface next to the rising air current. It's usually soot from candles or oil lamps, but it could be any airborne dirt.

[Nolan Kienitz]

Possible leaky connection of the TPRV into the main tank. Steam (aka: heat) seeping and heat causing discoloration on the painted surface?

Mind you that is only a WAG. [?]

[Nolan Kienitz]

JK's reply is the logical one.

Consider similar smoke traces at receptacle cover plates where AC/DC bricks are plugged in for long term for security system panels.

I had a newer home (built 2006) the other day that had a lot of such traces on outlet cover plates. Once I got into the attic and check the HVAC system and pulled the filter cover most of the cause was noted there as the filter was filthy. Lack of filters changes and accumulated dust/dirt in the carpet, etc., etc..

[Erby]

So, just plate out of particulate matter. Similar to ghosting on the studs.

Here's a filthy for you, from the same home.

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Must have had a "smart" agent. The filter was nice and clean!

Fortunately, The Pentax W90 almost always gives me a good shot of the blower fan blades.

"The main blower fan blades are covered with crud which impedes the operating efficiency of the unit. This has also usually allowed dust to come in contact with the wet air conditioning coils. Wet plus dust equals mud on the coils equals coils being partially blocked. I can't see the coils to verify this though. I recommend that you have a heating & air conditioning contractor service and clean the unit (to include removal and cleaning of both the fan and the coils)."

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