Why Is My Furnace Filter Black?

When the furnace filter first went into place, the screen was likely a grayish color. If a spot check reveals the filter turned black, this is something to pay attention to. The reasons can vary, and the problem may be minor or a sign of something serious. Knowing why could make it possible to know what actions to take.

Lots Of Dirt And Soot

An air filter collects dirt, dust and other impurities. Look for the filter to turn dark gray as it catches a lot of these things. Over time, if you don’t change the filter on schedule, it might become black. That filter is way overdue for a change.



Collected soot deposits can considerably darken an air filter. Soot can come from candles, fireplaces and other sources and travel through ducts. Eventually, they reach the furnace’s filter. Residue made inside the furnace might result from a mechanical or other problem. The issue requires a fix. Expert Air Control offers heating repair and maintenance to residents in the Puyallup, WA, region. Duct cleaning work is available, too.

Mold Growth

Unhealthy black mold grows wherever the environment is hospitable. Condensation collecting inside a heater creates the moisture necessary for mold to grow. Add impurities collected inside the heater to the moisture, and you may see mold growing. Eventually, mold makes its way to the filter. Upon discovering mold, taking quick action to get rid of it becomes vital. Some species of mold can be toxic.

Carbon Monoxide Leaks

Yes, carbon monoxide leaking from the lines can turn an air filter black and create a massive safety hazard. Carbon dioxide gas is also poisonous, which means the problem requires a repair immediately. Hopefully, the home has a carbon monoxide detector installed to warn the occupants. Homeowners should also learn what safety steps to take once upon discovering the leak.

Expert Air Control in Puyallup first opened its doors in 1979 and has remained a family-owned business ever since. Do you want help with furnace repair or installation? How about duct sealing? Call the service desk right away for any of your heating or  cooling needs.

Categories: Heating