What is a Cracked Heat Exchanger and How Do I fix it


A heat exchanger is a component in a furnace. It refers to a set of metal coils inside a furnace. This exchanger gets warmed directly by fire or gas inside the furnace and then transfers the heat from the exhaust fumes to your house after filtering out any harmful gases.

Types of Heat Exchangers

Usually, heat exchangers come in singles or doubles. If your furnace has a 70 – 80% efficiency rating, it has a single heat exchanger, while furnaces with 90% or more efficiency have two heat exchangers. These come with primary and secondary exchangers, with the primary one being the hottest as it is located close to the fire source. The heat from the primary exchanger is then passed to the secondary exchanger, turned into liquid. In this process, more heat is released, making these furnaces more efficient.

What Happens when the Heat Exchanger Cracks

One may wonder what the big deal is when a heat exchanger has a small crack. What is all the fuss about, and what happens if you ignore the issue? Well, the reality is that even the tiniest crack on your heat exchanger is fatal. The only difference is that it kills you slowly.

The first effect of such a crack is that the furnace will leak carbon monoxide. Unfortunately, carbon monoxide is a silent killer because it’s not easy to detect, yet it is highly poisonous. The moment you start experiencing headaches, dizzy spells, fatigue, and eye issues, then you should consider checking your furnace’s heat exchanger.

Detecting Cracked Heat Exchangers

Now that we have established the danger of a cracked heat exchanger, it is only reasonable that you find a way of fixing the damaged heat exchanger. Identifying the damage is the first step to fixing it. However, it is not always evident or obvious as one may assume. Usually, there may be no early signs until the situation is too late to fix. On rare occasions, the furnace may go off, but it works perfectly all through most of the time. Some of the obvious signs you could check to tell that your heat exchanger is cracked include having a furnace that does not heat up, the carbon monoxide detector going off frequently, and the recurring flu symptoms. Unfortunately, all these may not happen for all people, hence its dangers.

Fixing the Cracked Heat Exchanger

The moment you suspect a heat exchanger crack or fault, you should call an HVAC specialist. This is not a DIY project that you can handle on your own. Sometimes your carbon monoxide detector will not show any problem because of the low levels of carbon monoxide. However, HVAC specialists have the necessary tools to check and verify if you are in danger of CO poisoning.

Once the expert confirms the leak, then there is the likelihood that they will recommend a replacement of parts. You should never repair heat exchangers. Therefore, you need to buy a new exchanger and install it appropriately. Liaise with the professional HVAC technician to know which exchanger to go for. However, if the furnace is older than 15 years, replacing the entire heating unit is better than changing the exchanger alone. After all, even with a new exchanger, the furnace will still break down if it is too old.