How to Avoid Cracked Heat Exchanger Fraud!

Posted in: Heating

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Scam alert! This heating season, numerous heating contractors could be misleading customers about cracked heat exchangers in an attempt to sell more furnaces and collect more of your hard-earned dollars. At America’s Best Mechanical & Electrical, we pride ourselves in giving thorough and honest estimates, including you in the process and giving you options. In most cases where a technician has deemed a heat exchanger “cracked and unable to be replaced”, only about 10% of them are true. The rest usually turn out to be unethical tactics to sell new furnaces. Let America’s Best Mechanical & Electrical give you a first, second, or even third opinion. Don’t worry about scare tactics – we don’t use them!

In this post, I’ll share a few tips that can help homeowners recognize heat exchanger fraud. First let’s have a quick primer on the terminology and function of furnace heat exchangers.

The heat exchanger plays a central role in any furnace. It separates the warming flame from the air in the home. The burning fuel warms the heat exchanger which in turn warms the air in your home.


What are the dangers of a cracked heat exchanger?

Many people in the Philadelphia and surrounding areas heat their homes with fossil fuels (natural gas, propane, or fuel oil). When fossil fuels burn, they produce fumes containing carbon monoxide, carbon dioxide, water vapor, and soot. A furnace depends on the heat exchanger to contain these dangerous fumes and safety conduct them to the chimney/outside while transferring the valuable heat into the home. If the heat exchanger is compromised by a crack or rust, flue gases and carbon monoxide could leak into the home, resulting in illness and possibly death of the occupants.

What is the cause of heat exchanger cracks?

Nearly all premature heat exchanger cracks are caused by overheating. When a furnace cannot get enough airflow, the heat exchanger overheats and suffers excess stress from expansion and contraction. Over time, the heat stress causes cracks near weak areas such as bends or welds. The most common cause of an overheated heat exchanger is a simple as a dirty air filter. A clogged air filter restricts airflow through the furnace, overheating the heat exchanger, and eventually resulting in stress cracks.

An over-sized furnace can also cause overheating and heat exchanger cracks. Too much furnace with too little ductwork or too little house is a problem we see all the time. A furnace with under-sized ductwork will lack proper airflow and suffer a similar fate as that of a clogged filter.

The situation of a large furnace on a small home will take a bit more explanation. One of the byproducts of combustion is water. When a furnace first lights, the flame impinges on the cold heat exchanger and water vapor from the flame actually condenses on the inside of the heat exchanger. After just a few minutes of run time, the heat exchanger is warmed and the condensation evaporates. An over-sized furnace heats the home so quickly that the furnace shuts off after only a few minutes, so the heat exchanger stays wet and rusts from the inside out. The frequent cycling of an over-sized furnace also increases the expansion – contraction heat stress on the heat exchanger.

Proper diagnosis of a failed or cracked heat exchanger.

Diagnosis of a heat exchanger crack typically starts with a no-heat service call. A cracked heat exchanger allows air from the furnace blower to interfere with the flame causing it to flutter or even roll out. This trips a safety switch and shuts down the furnace. Beware of an unethical technician who finds a crack with a camera on a furnace that seems to be running just fine. While big cracks start as small ones, some technicians could search for anything that looks like a crack in order to sell a new furnace and earn a commission. We’ve even seen some technicians draw a line on the heat exchanger with a pencil, show the homeowner the line on a fiber optic camera, and convince them that it is a dangerous crack. Unreal!!! In 2009, the AHRI published a guideline for inspecting heat exchangers which states: “Any crack or hole that is big enough to affect combustion will be easily visible to the naked eye. Do not use water, cameras or smoking agents to check for leaks. Furnace heat exchangers joints are not hermetically sealed, so a small amount of leakage is normal.”

In most cases, a true crack will disrupt the flame or set off a carbon monoxide detector in the home. If you suspect a false diagnosis, call us for a free second opinion.

If a technician has condemned your furnace due to a cracked heat exchanger, simply explain that you would like a wrriten explanation of how they came to this conclusion. An honest company should have no problem standing behind their diagnosis and providing you with this thorough information.  If the problem is not evident or you’ve received a second opinion that does not conclude the same information, make the company reinstall your furnace and report them to the Better Business Bureau.

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