Heat Exchanger Problems


Old 11-29-02, 06:02 AM
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heat exchanger - hairline crack

Fall inspection by a heating contractor (sells furnaces). His heat exchanger test is mini tv camera on a wand inside the heat exchanger. Puts camera on bend at end opposite the burners. Then he sprays water on outside. After several moments the camera monitor shows an area darkening that looks like a hairline crack. I am told furnace fails for cracked heat exchanger and must be repaired or replaced. I question whether the kind of hairline imperfection, call it a crack, is a real problem. It doesn't look to me that any other part of compustion system including the flue would pass this kind of test so sensitive even capillary migration will cause a failure. Do I really have a problem and why if the "crack" isn't any worse than any other seam or joint in the combustion, collector, flue system? Thank you.
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Old 11-29-02, 07:23 AM
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Hello psterlin. Welcome to the Heating & Cooling forum & our DIY Web Site.

The sole reason no firebox cracks, regardless of the size or location of the crack, is allowed is simply because of carbon monoxides. Any and all burning gas, natural or propane, produces small amounts of CO.

During normal burning under properly controlled conditions, the amount of CO is minimal. Any crack in a firebox {Heat Exchanger} has the potential of altering the flames characteristics.

In most cases, depending upon where the crack is and how drastically it effects the flames, determines the amounts of CO levels created. Most often CO is prodced in unacceptable levels.

Even if little or no CO is currently being produced, once again depending on where the crack is, it will not remain at that level. Heat will further and rapidly cause more deterioration.

The current size of the crack will then become larger and the carbon monoxide levels will drastically increase. Cracks are very likely to then appear elsewhere.

If the furnace is new enough, a replacement heat exchanger
{Firebox} can be installed. If the unit is too old, replacement is the only option. Fireboxes are non repairable.

Resident heating professionals replying within this forum, may have alternate solutions, suggestions, opinions and or test and repair methods. Check back several times for additional replies.

If you need further assistance, use the REPLY button to add any additional information or ask additional questions after attempting the correctional method or methods offered.

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