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Posted

A client contacted my to conduct an Isolated Component Inspection on her HVAC System a few days ago. Today, I get to the property and she points out to me that she replaced her gas furnace with a new gas furnace two years ago. Recently, she has noticed soot deposits on the interior walls and around some of her electrical outlets.

Has anyone come across this before. I conducted a visual inspection of the furnace (explained to her my limitations) and found it to be in acceptable condition, but was perplexed on the soot on the interior walls.

The ducts are original to the residence and are about 33 years old. I did find that they were very dirty and contaminated.

any suggestions??

Posted

Kevin: How old is the house? That is an interesting question. Give me a buzz on the landline on Monday if you want. Call US Inspect HQ and they can give you my cell phone #. That looks like either air infiltation coupled with more indoor 'soot' of some kind. Air infiltration at outlets/switches occurs on lower levels, less on higher levels. (Stack effect and neutral pressure plane issues). I'd like to discuss it with you. US Inspect HQ # is 888 874-6773. Tell them I ok'd for them to give out my cell #.

Posted

She is a Massage Therapist and works out of her home, so I would assume that she does burn candles. However, do you think that a few candles would cause this amount of soot on the walls? The pictures I provided are just a few examples.

-Kevin

Posted

I've seen it happen with berber carpet. I thought it was bad padding recting to the Olefin. Turned out to be a mix between old furnace, airdraft from gaps in the subfloor and candles. A new furnace fixed the problem and saved me from replacing $2500 worth of brand new carpet.

Posted

The dark stains at those locations are from a leaky cold air return system. Some wall cavities are being depressurized and pulling air in. The soot may be from candles or a gas fireplace, or maybe just plain dirt.

If this only showed up after a new furnace was installed it's possible that the new furnace has a much larger blower than the old one. Is the furnace to big from the size of the house? Is there a balance between the registers and cold air returns? This is where I would start looking.

Posted

It looks like ordinary ghosting to me. Nothing too mysterious about it.

If you were to open up those areas, you'd find that there are voids in the insulation that are allowing those inside surfaces to cool more than the surrounding wall and ceiling planes. Warm, moisture-laden interior air moves toward those colder spots and clings to the surfaces just above dewpoint temperature. Dust particles in the air are trapped by that moisture and build up at those locations until the wall is discolored.

If candles are burned it can be more obvious but candles aren't necessarily needed. There's enough dirt in the air of a home without the soot to cause ghosting.

ONE TEAM - ONE FIGHT!!!

Mike

Posted

Candles oui... See it a lot. That soot goes places. Neutral plane/stack effect could be the driver of the incoming air, could be HVAC stuff as well. Basically though, it is probably 'the candles' and 'differentials in air movement' or the like leading to soot deposition on slightly-damper areas of walls or deposited at areas where there is greater flow across a surface (or something like that). Interesting because it looks odd at those outlets.

Posted
Originally posted by Rob Amaral

Interesting because it looks odd at those outlets.

I've seen quite a few of those oil-burning incense fragrance thingies that need to be plugged into the receptacle to heat the oil. I'm not talking the standard grocery store models.

These are actually little mini-frying pans so to speak. They work really well. I would think these things generate quite a bit of "off-gas" by-product.

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