Airtestco tests furnaces and return-air connections for leakage that may allow unfiltered crawlspace air to enter the home.

A furnace can be properly operating and still have openings around its cabinet or return-air connection. When the blower runs, pressure differences may draw air through these gaps. If a leak is located after the air filter, incoming air can bypass filtration and enter the HVAC system.

Call Airtestco: 720-527-8510 to discuss a crawlspace furnace air-leak inspection.

CONTACT A CERTIFIED HVAC CONTRACTOR

Airtestco looks for openings and bypass paths at accessible parts of the furnace and return-air assembly, including:

• Gaps in or around the furnace fan compartment and cabinet panels.
• An unsealed connection where the return plenum meets the furnace frame.
• Openings downstream of the air filter where air may enter without passing through the filter.
• Loose, disconnected, or poorly sealed return ducts and transitions in the crawlspace.

Airtestco has found leakage gaps in more than 80% of the furnaces inspected for this concern. This is Airtestco’s field observation, not a claim that every furnace has a leak or that every leak introduces crawlspace air into the home.

Mold and other fungi occur naturally in soil, including crawlspace soil. Fungal spores are common in the outdoor environment. Their presence in soil does not, by itself, mean a home has a mold problem.

The concern is whether damp or contaminated crawlspace air has a pathway into the HVAC system and occupied rooms. A gap on the return side, especially one that allows air to enter downstream of the filter, may let air and particles bypass normal filtration. The actual direction and amount of airflow depend on the system’s design, operating pressure, and location of the opening.

Airtestco performs a focused, non-destructive inspection of accessible furnace cabinet areas, the fan compartment, the filter arrangement, and the return-plenum connection. With the system operating when appropriate, we use airflow indicators such as a smoke pen and other field observations to help identify air movement at suspected gaps.

The inspection is intended to identify observable leakage pathways and conditions that may allow crawlspace air to enter the system. It does not identify every concealed defect or determine the health risk of a particular exposure. If a repair is needed, Airtestco can document the location for discussion with a qualified HVAC contractor.

• The furnace and return ductwork are located in a crawlspace.
• Dust or debris appears around furnace cabinet seams or the return connection.
• Musty crawlspace odors are noticeable when the heating system operates.
• There are visible gaps around the fan compartment, filter slot, or return plenum.
• The crawlspace has moisture, damp materials, or visible fungal growth.

These signs do not confirm that crawlspace air is entering the home. Testing helps determine whether an observable pathway is present.

Airtestco provides independent indoor environmental inspections and does not perform remediation or HVAC repairs. That lets us focus on evaluating and documenting conditions without selling the repair work.

Concerned that your crawlspace furnace is leaking? Contact Airtestco to discuss an inspection of the furnace cabinet, return-air plenum, and accessible duct connections.

Call 720-527-8510 · Airtestco.com

It can if air is drawn from the crawlspace through a leak in the return-air system or furnace cabinet. The furnace location alone does not establish that this is happening; airflow and the condition of the system need to be checked.

Not if air enters the system downstream of the filter or bypasses the filter through gaps. Filter fit and the location of each opening matter.

No. Fungi and spores occur naturally in soil and outdoor air. The relevant questions are whether there is a moisture problem and whether an air pathway is carrying crawlspace contaminants into the home.

No. Airtestco provides independent testing and documentation. HVAC repairs should be completed by a qualified HVAC contractor.