HVAC Dust or Soot Stains
How to Diagnose Soot & Other Indoor Wall or Ceiling Stains Traced to
Heating or Air Conditioning Equipment
STAINS HVAC SOOT or DUST - CONTENTS: Soot stains indoors caused by defective oil or gas fired heating equipment or debris stains caused by HVAC air movement. A photo-guide to heating systems as the source of some indoor ceiling and wall stains and what they mean - heating system trouble
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This article describes & diagnoses heating equipment as the cause of various interior wall and ceiling stains and explains how to recognize thermal tracking, thermal bridging stains,
building air leaks, and building insulation defects.
Often these stains are mistaken for toxic indoor mold. When investigating a building for a mold problem, you can save mold test costs by learning
how to recognize Stuff that is Not Mold or is only Harmless Mold but may be mistaken for more serious contamination.
There are no stains or soot marks on the building walls where pictures have just been removed
Black sooty stains are less dark on the wall surface as we move higher on the wall away from the heating register
Black sooty stains on other walls in the room are much less noticeable
Dirt, Debris, Stains around Heating or Air Conditioning Air Registers
The soiling and "stains" around this ceiling supply register for warm air or air conditioned cool air show that the air system is dirty, has inadequate filtration, or is operating unsafely.
While mold or other problem particles could be present in this dirt or debris, if they are present they are coming from another source, not from this soiled area on the ceiling.
Here the debris deposited on the ceiling is in a common pattern where warm or cool air supply registers blow air across the ceiling surface (including from leaks around the perimeter of the register grille in this case.)
The stain pattern is from building air movement, it is not thermal tracking and it is not, by itself, an indicator of problem mold. A lab test of this debris for the presence of mold would not be justified based only on the observation of these stains, but it might be justified if there were other reasons to need to screen the building or its HVAC system for problem mold or other contaminants.
If you have frequent fireplace fires, cooking, or if you burn scented candles, if people smoke in your home, or if your oil-fired or gas-fired
heating system is not working properly, the added soot particle load in the building air
is not only a health concern (soot and potentially lead), it also will mark the building surfaces in this characteristic pattern.
We welcome more thermal tracking, soot tracking, air bypass leaks, and similar photos of indoor stains as well as text suggestions to expand this detail and would be glad to credit contributors.
Usually soot marks, thermal bridging, or thermal tracking stains appear, if at all, in the building interior locations discussed
in the remaining sections of this article.
Normal House Dust Deposits at a Heating or Air Conditioning Air Register
Above the light gray dust depostis at this heating air supply register look normal - that is, house dust, comprised princiapally of fabric fibers and skin cells is usually light gray in colour in such deposits. Only by examination in a forensic lab will we know for sure what's in the dust on this register, but unless there is reason to suspect that there are contaminants in the system such testing is normally not appropriate.
See MOLD / ENVIRONMENTAL EXPERT, HIRE ?- when to hire an expert
Below is a close-up example showing typical light dust deposits on an air supply register. The rust, depending on its cause and the source of moisture, might lead to a question of moisture, condensation, or perhaps mold contamination in the duct work of this building.
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Questions & answers or comments about wall or ceiling stains that are traced to heating system problems.
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ASHRAE resource on dew point and wall condensation - see the ASHRAE Fundamentals Handbook, available in many libraries. The following three ASHRAE Handbooks are also available at the InspectAPedia bookstore in the third page of our Insulate-Ventilate section:
2005 ASHRAE Handbook : Fundamentals
: Inch-Pound Edition (2005 ASHRAE HANDBOOK : Fundamentals : I-P Edition) (Hardcover), Thomas H. Kuehn (Contributor), R. J. Couvillion (Contributor), John W. Coleman (Contributor), Narasipur Suryanarayana (Contributor), Zahid Ayub (Contributor), Robert Parsons (Author), ISBN-10: 1931862702 or ISBN-13: 978-1931862707
2004 ASHRAE Handbook : Heating, Ventilating, and Air-Conditioning: Systems and Equipment : Inch-Pound Edition (2004 ASHRAE Handbook : HVAC Systems and Equipment : I-P Edition) (Hardcover)
by American Society of Heating, ISBN-10: 1931862478 or ISBN-13: 978-1931862479
"2004 ASHRAE Handbook - HVAC Systems and Equipment The 2004 ASHRAE HandbookHVAC Systems and Equipment discusses various common systems and the equipment (components or assemblies) that comprise them, and describes features and differences. This information helps system designers and operators in selecting and using equipment. Major sections include Air-Conditioning and Heating Systems (chapters on system analysis and selection, air distribution, in-room terminal systems, centralized and decentralized systems, heat pumps, panel heating and cooling, cogeneration and engine-driven systems, heat recovery, steam and hydronic systems, district systems, small forced-air systems, infrared radiant heating, and water heating); Air-Handling Equipment (chapters on duct construction, air distribution, fans, coils, evaporative air-coolers, humidifiers, mechanical and desiccant dehumidification, air cleaners, industrial gas cleaning and air pollution control); Heating Equipment (chapters on automatic fuel-burning equipment, boilers, furnaces, in-space heaters, chimneys and flue vent systems, unit heaters, makeup air units, radiators, and solar equipment); General Components (chapters on compressors, condensers, cooling towers, liquid coolers, liquid-chilling systems, centrifugal pumps, motors and drives, pipes and fittings, valves, heat exchangers, and energy recovery equipment); and Unitary Equipment (chapters on air conditioners and heat pumps, room air conditioners and packaged terminal equipment, and a new chapter on mechanical dehumidifiers and heat pipes)."
1996 Ashrae Handbook Heating, Ventilating, and Air-Conditioning Systems and Equipment: Inch-Pound Edition (Hardcover), ISBN-10: 1883413346 or ISBN-13: 978-1883413347 ,
"The 1996 HVAC Systems and Equipment Handbook is the result of ASHRAE's continuing effort to update, expand and reorganize the Handbook Series. Over a third of the book has been revised and augmented with new chapters on hydronic heating and cooling systems design; fans; unit ventilator; unit heaters; and makeup air units. Extensive changes have been added to chapters on panel heating and cooling; cogeneration systems and engine and turbine drives; applied heat pump and heat recovery systems; humidifiers; desiccant dehumidification and pressure drying equipment, air-heating coils; chimney, gas vent, fireplace systems; cooling towers; centrifugal pumps; and air-to-air energy recovery. Separate I-P and SI editions."
Energy Savers: Whole House Systems Approach to Energy Efficient Home Design [copy on file as /interiors/Whole_House_Energy_Efficiency_DOE.pdf ] - U.S. Department of Energy
"Energy Savers: Whole-House Supply Ventilation Systems [copy on file as /interiors/Energy_Savers_Whole-House_Supply_Vent.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11880?print
"Energy Savers: Whole-House Exhaust Ventilation Systems [copy on file as /interiors/Energy_Savers_Whole-House_Exhaust.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11870
"Energy Savers: Ventilation [copy on file as /interiors/Energy_Savers_Ventilation.pdf ] - ", U.S. Department of Energy
"Energy Savers: Natural Ventilation [copy on file as /interiors/Energy_Savers_Natural_Ventilation.pdf ] - ", U.S. Department of Energy
"Energy Savers: Energy Recovery Ventilation Systems [copy on file as /interiors/Energy_Savers_Energy_Recovery_Venting.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11900
"Energy Savers: Detecting Air Leaks [copy on file as /interiors/Energy_Savers_Detect_Air_Leaks.pdf ] - ", U.S. Department of Energy
"Energy Savers: Air Sealing [copy on file as /interiors/Energy_Savers_Air_Sealing_1.pdf ] - ", U.S. Department of Energy
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