Carbon Monoxide and Heat Exchangers

Carbon monoxide, the poisonous, colorless, odorless and tasteless gas responsible for more than 20,000 visits to the emergency room every year, can pose a danger from unexpected sources in your home, including fireplaces.

 

What is a heat exchanger and why is it critical?
A furnace's heat exchanger is a metal component that transfers heat from the fuel being burned while keeping the air in your home from mixing with the furnace exhaust. Sometimes the heat exchanger fails, either from cracks caused by regular expansion and contraction due to heating and cooling of the metal, or from rust. When a heat exchanger fails—under specific conditions—the exhaust gases, including carbon monoxide, can blend with the air in the house. A properly running furnace should not generate significant levels of carbon monoxide; however, a cracked or leaking heat exchanger can present a safety hazard.

What are the dangers connected with a cracked heat exchanger?
A cracked heat exchanger could permit exhaust gas from the furnace to contaminate the household air with exhaust gases including carbon monoxide. In order for this to happen, the furnace must be giving off high levels of carbon monoxide and the exhaust gas must be mixing with the household air. This could lead to serious illness and even death.

Beyond a visual inspection to establish a crack, there are a few warnings of a potential complication with your heat exchanger that you may notice. If you turn the heat on and the flames flicker and seem devilish, this could be a indication that circulated air from the furnace is getting into the combustion area and you should have it examined by an HVAC technician. Although you certainly hope it doesn’t reach this point, other signs of trouble include carbon monoxide detectors sounding and you or your family members feeling sick, lightheaded or nauseous. To ensure the safety of all occupants, all homes should have a working carbon monoxide detector and batteries should be replaced regularly.

How can I be positive that my heat exchanger really has failed?
Service Experts’ ACE-certified technicians have received specialized training in observing a cracked heat exchanger. As standard practice and in addition to physically observing the presence of a hole or crack, cameras are used. Whenever possible, the technician will show customers the failed heat exchanger—or at least a photo of it—so they can see for themselves. Additionally, an expert technician will test both the home and furnace for carbon monoxide. A properly operating furnace should not generate significant levels of carbon monoxide. The technician will then warn the customers of the dangers associated with the failed part and offer professional advice regarding next steps.

What happens after an HVAC technician diagnoses a cracked heat exchanger?
Once you have a confirmed diagnosis from an expert, your fundamentalquestion will likely be whether the part can be repaired or if replacement is the only option. Unfortunately, industry standard is that the heat exchanger must be replaced. In fact, the American Gas Association advises that any visible crack or hole is reason for requiring replacement of the heat exchanger or furnace.

 

If my heat exchanger has failed, do I have to replace the furnace?
While it may end up making sense to replace the furnace as opposed to only the heat exchanger, that is not always the case. Furnace warranties can vary—most furnaces have a 10-year warranty on the heat exchanger, while some are covered for 20 years or even for the life of the furnace. Our technicians will help you understand the warranty on your heat exchanger and provide all the information you need to decide if replacing the heat exchanger or the entire furnace is right for you.