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About Visible Defects™

What is the Visible Defects™ Visual Inspection System?

Service Tech Using VD

The Visible Defects™ Visual Heat Exchanger Inspection System is a patent-pending way to provide Service Technicians with an accurate, cost effective, non-destructive inspection process to identify potentially hazardous defects in fuel fired furnaces.

The Inspection System is a dye penetration inspection(DPI), also known as a liquid penetrant examination (LPE). This is a type of nondestructive testing used generally in the detection of surface breaking flaws.

Visible Defects™ uses a highly sensitive, patent-pending, bright green, fluorescent dye called Contractors Crack Finder and a black (ultraviolet) light to illuminate the residual penetrant. Contractors Crack Finder is low odor, non-toxic, no smoke, and fluorescent; designed to penetrate even the tiniest hairline cracks that are often found in the heat exchangers of furnaces.

The dye is easily applied to the entire heat exchanger using our spray bottle with its special nozzle and hose attachment. The application equipment applies the dye through holes as small as one-eigth of an inch. These holes are common in the front panels on most furnaces (like when you remove a sheet metal screw that holds the front panel in). Dye can also be injected directly into the cells (tubular).

How does it Work?

UV Illuminated Heat Exchanger

Standard Heat Exchangers: Spray the dye onto the "air-side" of the heat exchanger, through the holes in the front panel. You would then inspect the "combustion-side" of the heat exchanger using a black-light flashlight and an inspection mirror.

Tubular Heat Exchangers: (i.e. Amana, Coleman, Goodman, Luxaire, Nordyne, York, and some commercial package units) Inject Contractors Crack Finder into the tubes at the combustion chamber by the burners. You would then inspect the heat exchanger from the "air-side" throught the plenum, the insertion limit, and the blower compartment using a black-light flashlight and an inspection mirror.

If the fluorescent green dye has penetrated the heat exchanger, this indicates a breach. You have potentially found a heat exchanger crack or defect indicating the heat exchanger or the furnace must be replaced.

CAUTION: A very small amount of dye present only in the seams of "crimped" style heat exchangers may be normal and requires further inspection to verify whether or not a crack or defect exists.

Why Condemn Heat Exchangers? What Gives Me the Authority?

The American Gas Association (AGA) has produced a document called 'Furnace Heat Exchanger Leakage Test'. It is the Industry Standard that the courts will hold us responsible to follow.

The Industry Standard states: "The first step in the test procedure involves a visual examination of the heat exchanger." It further tells us that "any visible crack or hole discovered in this step is reason for requiring replacement of the heat exchanger or furnace."

As a contractor, given these guidelines, you have no choice; ANY visible hole or crack REQUIRES REPLACEMENT of the heat exchanger or furnace.