Do technicians lie about cracks in heat exchangers?

Cracked Heat exchnagers: Do technicians lie about cracks in heat exchangers?

I recently was called to a home after a competitor told her she had a crack in her heat exchanger. A breach or a crack in a heat exchanger can be common in equipment as early as 5 years after installation.

Many times homeowners have no clue as to what a technician says is accurate. In this instance something didn’t sound right. The company was out for a $69 tune up special. The system was located on the roof and within 5 minutes of the technician being there he was already downstairs telling the homeowner she needed a new system. Worse yet he had a carbon monoxide detector saying the reading was at 2 parts per million and rising fast to 3 parts per million. The US EPA states the average home has from .05 to 5 parts per million and that is average. ( to Reduce Exposure to Carbon Monoxide).

The company told her she had to replace her system and that she had not other options available. When the technician I work with showed up he could not find a crack or breach in the heat exchanger after 40 minutes of looking. There are plenty of legitimate cases where a heat exchanger cracks and a technician should be able to show you either by taking your furnace apart or by using a special camera where the damage is.

If it feels like there is something wrong with what a technician is telling you, you are probably right. Just as in any other industry there are a few bad apples that can ruin the load for the rest. There are plenty of times where heat exchangers are cracked and the technician should be able to show you through video or a picture of where the damage is. just like in any other industry some technicians get training while others do not.

A crack is a crack and it doesnt matter location or size, Once the crack appears the part is defective and a call to any manufacturer will allow you to learn the same. They dont ask where it is or how big it is they just change it out under warranty if still in warranty.

As always I am not there in your home to look at your system. It is up to you to hire a qualified company to come out and show you for sure.

What does it mean to red tag a furnace because of a crack in a heat exchanger?

.When a crack in a heat exchanger is found by a technician or utility company sometimes the words or phrase “red tag” is used. This means that the furnace is shut down by the company or utility company making it inoperable to use. In these instances either the electrical cord is unplugged or the gas valve is disconnected and the gas line is capped off.

If the utility company is the party who capped off the gas line to the furnace due to a crack or breach in the heat exchanger you may be breaking the law if you reconnect to the gas line. You are adding a huge liability by doing so (this article is not legal advice). If it was the heating and air conditioning company that capped off or “red tagged” your furnace they may have to do so based upon state or local law.

To go back to determine whether or not your furnace or heat exchangers should be replaced due to damage or even a crack in the heat exchangers go back to the rule of any crack or breach that is visible is reason enough to replace the heat exchangers. As a side note  I am not in your home so I am not able to diagnose your situation make sure your technician is trained to do the inspection.

So how much should the replacement of your heat exchangers cost if your furnace is red tagged?

Depending on your furnace and whether or not the heat exchangers are under warranty the costs may vary. Some companies charge as little as $1,500 to change the heat exchangers on some models and as much as $3,000. There are some heat exchangers from the manufacturer that cost $4,500 for the dealer so it really depends.

What to do when your furnace is red tagged is going to be up to you. You may live in a mild climate and may not be using the furnace so it may be better to replace them. If your system is over 10 years old that may not be a wise solution to the problem. In many instances it is best to replace the furnace due to a crack or a breach in the heat exchanger. When replacing a heat exchanger cell due to a red tag it may take up to 4 weeks to get the parts from the manufacturer depending on the time of the year and their shipping schedule. If the shipping is going to take a while your best option may be to replace your furnace.

A red tagged furnace is a serious matter and should be dealt with as such. There is such thing as a good crack in a furnace or even a hairline crack. If you have a furnace that is found to have a problem with the heat exchanger take the recommendations from the technician seriously to replace the furnace.

Once again I am not able to be in your home. Make sure your technician has been trained on the proper procedures to look at your furnace for flame roll out and or cracks in the heat exchanger.

Replacing your furnace once a crack is found in the heat exchnager

Once you determine that you are going to replace your furnace because of a crack or thermal stress points on a heat exchanger you do have some options.

Your new furnace can be one of 2 efficiencies it can either be replaced with a 80% or a 95 %. The percentage indicates how much fuel is consumed and how much fuel is lost through the burn cycle. For example an 80% furnace utilizes 80% of the fuel and 20% is lost, or for every $100 used for a gas utility you are using $80 dollars.

 More than likely the furnace you have currently is less than an 80% efficiency. In some instances it may be more efficient. There are a few things to look at after replacing a system because of a crack in a heat exchanger. First you would look at your monthly heating bills and determine how much comes from heating since some gas of fuel may be used to heat water or to cook with. If you are not planning to use more heat in the future you may just want to stay with a 80% furnace. On the other hand the federal government does offer up to  $1500 tax credit to increase efficiency to a 95% furnace or more. In some instances this change can benefit you in the future because of energy savings and or the tax credit depending on how your taxes are done.

What will work best for you is determined by how much you have set aside to spend or what portion can be financed and also by how much energy you hope to save on fuel costs.

Your salesperson or technician should be able to help you determine what system is best for you once you replace your furnace due to a crack found in the heat exchangers. For you there may be a favorite brand you have to begin with and that is fine but your new system and the efficiency that you get will be determined by the installation.

What to expect if you get a second opinion on a cracked heat exchanger


When a crack is found in a heat exchanger while working on or performing maintenance sometimes homeowners are concerned if their technician is being honest with them.

This is common because once a breach or crack is found in the furnace there is pnly 2 things that can be done either replacing the damaged heat exchanger, faceplate or even by replacing the furnace.

Most concern happens from homeowners because there was no real sign of damage. The confusion happens because the furnace will still turn on and off and may not trigger the safety devices that are built in to the furnaces now. If someone were to spend an hour working on my furnace and then share with me that I needed a new one I would have the same questions.

There is too much confusion as to what is or is not damage to a furnace and if it is harmful. As a disclaimer I am not there to inspect your furnace so any damage that is found should be verified by your technician. The rule that is most common is any crack or breach that is found in a heat exchanger is reason enough to replace the heat exchangers or replace the furnace period. Unless there is a technical update from a manufacturer there is no quick fix, welding or cement that can be used as temporary fix. There are some technicians that have never taken courses in furnace inspection and it really isn’t taught well in most schools.

There are times where a technician will say that the damage to the heat exchanger is not in a dangerous spot or that the crack in the heat exchanger is not big enough to worry about. We will go back to the rule that any visible crack in a heat exchanger cell, tube or rivet is reason enough to move forward with either of the 2 options outlined above.

As a consumer your questions to the technician should be how did they find the crack or breach in the heat exchanger and how were you trained to find them. There have been times where there are technicians who have never been trained who are verifying damage.

If you do want a second opinion the best thing to do is have both companies there at the same time. This way both parties can look and decide at the same time. There are two ways to do this: either the entire furnace has to be taken apart to expose the entire heat exchanger or a special camera can be used along with a water test to see is there is any damage.

If the entire furnace is pulled apart the crack or breach may or may not be visible without proper training. This is why the education of your technician is so important.

For a water test the outside of the heat exchanger cell is sprayed with a layer of soapy water. The soap allows the water to penetrate the crack or breach, a camera or mirror is placed inside the heat exchanger and if there is water that penetrates through then there may be a crack. The explanation of may be is used because some seams or crimped metal heat exchangers may allow water to soak through.

Some people will say that there is no carbon monoxide coming through the ventilation system and it should not be worried about. Go back to the rule that any visible crack on the heat exchanger or faceplate is reason enough to replace the heat exchangers or furnace. It is possible that you may be uncomfortable for a few days or a few hours by not being able to use the furnace is better than the alternative. As mentioned in a previous article some states require that once damage is found that the furnace is made inoperable. In some areas only the local utility has the ability to condemn a furnace. As a consumer it is within reason to ask what ever technician that comes to your home how he or she has been trained on detecting a crack or a breach in a heat exchanger. If they have not taken the time to take a course from trained professional they may or may not be able to determine the abilities of your furnace.

Once again as a disclaimer it is important that you do your homework and get the right technician to your home. I cannot be in your home to inspect your furnace. If damage is found then it is up to you to replace your furnace.

Is it a good idea to sign up for yearly maintenance or just get it performed randomly?

Most companies offer specials for heating or air conditioning tune ups, the range anywhere from $39 a visit to $99 at least this is the case in the Sacramento and surrounding areas. If performed correctly the tune up should allow for your system to perform longer at a better energy efficiency. I will give you a list of things that need to be done on a furnace tune up so you can ask questions:

  • Set the gas valve to specifications – They are not set from the factory and should be set during installation
  • Check the ignition system – Sometimes the igniters break or become damaged
  • Check the safety devices – Make suet they shut the system down
  • Clean the burners or burner assemblies  – they will build up carbon and can create damage to the heat exchanger if not directed properly
  • Check the exhaust flu for proper exhaust – it may be blocked or installed incorrectly
  • Clean the blower wheel if needed – If the blower wheel is dirty it wil not move enough air flow for heating or cooling
  • Check the capacitor on the blower wheel and or exhaust motor – they are a back up source of energy to help a motor run, almost like a battery but not
  • Check and monitor the amp draw of motors – The motors can go bad, do you want to know in a mild climate or in an emergency
  • Perform a safety inspection of the heat exchanger


There is a difference between what companies consider tune ups and it is buyer beware situation.  A normal heating or air conditioner tune up should take an hour or more and if there is any damage or issues noticed the technician should be able to explain what your options are. If your system has some age to it being 12 years or older it may be in your best interest to replace the system for better reliability and or efficiency.

For the safety inspection ask how the technician was trained. That I know of there are only 2 companies who train technicians how to look for the damage to a furnace. These instructors will share that manufacturer of the product or the warranty that comes with it should be reason to exclude a safety inspection. I have seen a top manufacturers furnace have a crack or a breach in the heat exchanger at 3 years old.

Your best bet is to sign up for a plan where the company charges you by the month to perform the services. Monthly is better because if the company goes out of business you will not lose much vs giving the yearly amount up front. These services can be from $100 a year for a stand alone furnace to $200 for an air conditioner and a furnace. These plans should give you some sort of a discount along with priority dispatching during the hot and cold season.

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Answers to your questions about replacing a furnace with more features like staged gas valves and variable speed

New furnaces have more energy saving features than that of furnaces even 5 years ago. With many people minds reaching to energy conservation instead of consumption most manufacturers have increased their offerings to consumers. In general the United States is a few years behind in technology compared to the Japanese and some of the countries in Europe but we are getting close.

When it is time to replace your furnace there are a few things to look at:

AFUE that is Annual Fuel Utilization Efficiency is based on a percentage. The standard or minimum efficiency allowed by law id 80% that means for every $100 you spending gas with your utility $80 is used $20 is lost some manufacturers have furnaces that reach into the category of only having a 2% loss with a 98% efficiency.

The next category to take a look at is stages on the gas valve. A standard or basic furnace may come with only an on or off setting meaning that the gas setting is single stage. Some manufacturers deliver their product standard with a 2 stage gas valve. This means that the lower stage may use 70% of capacity. That would be if you have a 100,000 btu furnace (a btu is one lit match, furnaces are measured by the hour) with a 2 stage vale would start at 70% of capacity or 70,000 btu’s and if needed because of demand from the thermostat the gas valve would increase to 100% giving all capacity of the furnace. Next would be modulating where the gas valve in the furnace could have anywhere from 12 to 65 different settings for heat.

The more settings on the gas valve the more possibility the furnace has to save energy.

Last on the list of features for a furnace would be the different types of blower wheels or the fan that moves the airflow into your home. Standard furnaces are set up with single speed motors so when your furnace is running the airflow comes out in 1 speed at 100%. More energy efficient furnaces come with variable speed where the internal control or mother board of the furnace determines how fast the airflow needs to be (As a side note this feature will only really deliver the right type of airflow once proper adjustments are made to the ductwork. This means there has to be enough air going in to get enough air going out. The only true way to test this measurement is by taking the static pressure or blood pressure of the ductwork).

The combination of staged gas valves and variable speed furnaces do equate to better energy savings and when installed correctly the life of your heat exchanger should also benefit. It is up to you and your chosen heating and air conditioning company to match the right combination for your needs.

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What is a thermal stress point or temperature stress point

up close view of heat exchanger damage

thermal and temperature stress on heat exchanger

What is a thermal stress point or temperature stress point

The next time you have your furnace looked at your service technician may explain to you that the heat exchangers in the furnace are showing signs of thermal stress or temperature stress points.

For this article I have to explain that I am not in your home an it is up to you to use your judgment to decide what you should do once damage to your furnace is found, whether it is a crack or breach in the heat exchanger or a thermal stress point.  

When a furnace heats up there will be a point on the heat exchanger that does get more heat from the flame of the burner or may get hotter due to the internal structure and location of the blower wheel. Lets start with the first example. When the burners are off center or even are over firing they can heat up one section of the heat exchanger more than another. After time this excessive heat will cause a temperature stress point or thermal stress.

Every manufacturer designs their furnaces differently and sometimes the internal structure blocks some of the airflow from the blower wheel causing a section or area to over heat. That internal design can cause damage to the heat exchanger since the heat exchanger is not cooling properly.

In either example of over firing or internal design issues once a heat exchanger in a furnace starts to show wear and tear to the heat exchanger it will not stop, left unattended it may break or develop a breach causing a safety concern.

Depending on what a technician shares with you and what you feel comfortable with is how you should deal with the situation since I cannot be there to diagnose the furnace myself.

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Should you buy the extended warranty on your furnace when you invest in a new one

A long time ago equipment and appliances were made to last. By today’s standard  heating and air conditioning systems are more efficient but they do have a shorter life span than they did previously to the mid 1980’s.

I get asked when I get a chance to help homeowners chose as system if they should buy the extended warranty, my answer is almost always yes.

There are a few reasons 1. you will have failure and it isn’t going to be like the old system. 2. The more technology a new furnace or air conditioner has the more its going to cost to replace parts down the road. 3. It feels good to know later down the road that a system is covered  no matter what happens.

In most instances I personally do not buy the extended warranties on computers or electronics but fro something that could have repairs in the $1000’s.

The factory is going to have some sort of warranty on parts for your furnace and or air conditioner and that is either 5 or 10 years a few companies do offer 12. For the labor most manufacturers offer the first year of labor.

On a heat exchanger the warranty can be 10 years, 20 years or lifetime for residential homes.

Here is what you need to know. There is a huge difference between an in house extended warranty and a factory extended warranty for your furnace of air conditioner. With a factory warranty the factory pays the company who fixes your equipment after you pay for them to come diagnose the situation.

An in house warranty is an implied warranty from the company who installs your equipment. If something ever happens to this company like going out of business your warranty is lost.

The extended warranty should cost you somewhere around $675 for a complete system from the factory.

From an in house warranty it shouldn’t cost anything because it isn’t worth the paper its written on.

If you are a homeowner and you plan on living in your home for over 10 years it would be my recommendation to buy the extended warranty.

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When is the best time to repalce your furnace?

I get asked daily by homeowners in the Sacramento Valley, “When is the best time to replace my heating and air conditioning system”?

My answer to them is a question and that is, “Are you proactive or reactive”?

Lets find out what side of the coin you are on.

  1. Would you rather take care of a problem before it happens where you have some control in getting what you want when you want it?
  2. You want to have to take what you can get in an emergency?


If you answered A. the best time is when you can that would be right now. If you answered B. that would be when the temperature is over 100 degrees during the summer or under 40 degrees during the winter.

Taking care of an issue before is becomes an emergency gives you more power than you think. Some people decide that they are comfortable with a company that they have done business with before and can go ahead and be comfortable with moving forward. Some people have to think over all sorts of things while they suffer and are uncomfortable looking for who knows what, a brand, a price or something else.

So what group are you in?

If it were over 100 degrees outside and your system had major failure how much would you pay to keep comfortable?

What is your answer if you were freezing cold and your furnace was broken?

How much of a premium would you pay top be comfortable again?

In an emergency situation how much mark up do you think that most companies have?

Yes there are companies out there who have prices that can vary as much as 40% between peak seasons.

So are you proactive or reactive.

 My hopes for you are that you take the time to have your furnace inspected and use the proactive route so you can make a decision in your own time instead of in an emergency.

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Do you need a Carbon Monoxide detector or alarm in your home.

“Do I need a carbon monoxide detector or alarm”? is a question that I get asked many times a year. The answer is always yes you do need a detector that picks up Carbon Monoxide. Even if you do not have any gas fired appliances it is a good idea.

I have had people tell me that they do not need a safety inspection of their furnace because they have a Carbon Monoxide detector or alarm. I have to share with them that they do need a safety inspection on their furnaces heat exchanger yearly even if they do have an alarm or detector.

The biggest question is “What if you rely on technology and it doesn’t work or fail when you need it”?. People have a tough time remembering to change the batteries in their smoke detectors and some people do not even know if their smoke detector works. So what if you do have a carbon monoxide tester and id fails?  

I have also had people share with me that the system isn’t old enough to have a crack or a breach in a heat exchanger so it doesn’t need to be inspected. For you to know I have seen furnaces that are 9 months old have a crack, and that is 9 months. It has become more common for me to find breaches or cracks at 5 – 7 years. A “short” or “early” age is not a good reason to not have a safety inspection on your furnace yearly. When in doubt consult your manufacturer or a local company who can do the inspection.

Falling back on the rule that a visible crack in a heat exchanger is reason enough to replace the furnace or the heat exchangers not on the output of carbon monoxide in a home is also the main reason that your furnaces heat exchanger has to be inspected every year. The roughly $80 – $100 that most companies charge to do an annual preventative maintenance will be well worth it for you.

There have been times where I have found a crack or a breach in a heat exchanger and another company will come out and place a carbon monoxide tester in the airstream instead of a visual inspection. There is no replacement for the complete visual inspection for your cracks or breaches in your heat exchangers. I have placed my carbon monoxide tester in the airstream of furnaces where I have found damaged and not even registered carbon monoxide, even then the rule applies either replace the heat exchangers or replace the furnace

Some companies even will do free or complimentary inspections for you if you ask. In some or most cases they will even do a second opinion for free. If someone would like a second opinion for a diagnosis I make I prefer to be there with them because some companies do not train or take courses on procedures for heat exchanger failure inspections. In the instances where companies have showed up with me there they didn’t even find the breach that I found.

For you as a consumer it is ok for you to ask where and who has trained the companies technicians or what happens if there is a misdiagnosis.

As a reminder I can not be there in your home to take a look at your furnace. It will be up to you to check out the company you choose to take a look at your furnace and your heat exchangers.  It is normally stated in your furnaces packet that the system gets maintenance yearly specifically for this reason.

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