March 12, 2010
-- The heat exchanger is the lynchpin of a forced air furnace. But it is actually much more than that; if a heat exchanger fails or cracks, it poses a fatal risk to a household. Properly functioning heat exchangers separate the toxic gasses produced during combustion from the clean, warmed air used in forced air heating systems. However, when heat exchangers develop cracks or holes, carbon monoxide (CO) detectors prove they can emit dangerously high levels of the invisible, odorless, deadly gas—carbon monoxide. According to the Center for Disease Control, 500 Americans die from carbon monoxide poisoning every year and another 15,000 suffer carbon monoxide poisoning illnesses.
The heat exchanger in a home heating furnace is a metal chamber that contains the combustion process and vents all the dangerous gasses produced out the exhaust stack. When the furnace turns on and initiates combustion, the heat exchanger heats up while containing all the dangerous gasses produced. When the heat exchanger reaches a high enough temperature, the furnace’s blower turns on, pulling cool air from the return duct and blowing it across the hot heat exchanger, into the ducts that heat the home. Therefore, if a crack develops in the heat exchanger, the possibility that deadly gas can be blown into the home is all too real.
Carbon monoxide detectors installed in residences repeatedly reveal this threat. Firefighters nationwide have records of answering calls for CO detector home alarms that led to discovery of cracked heat exchangers emitting dangerous carbon monoxide inside residences.
However, there is some controversy within the heating and air conditioning (HVAC) service industry regarding the degree of urgency called for by a cracked or failing heat exchanger. Some argue that because there are known cases of heat exchangers with small holes that merely vented the deadly gasses up the flue and not into the home, there is no call for immediate action to repair or replace a faulty heat exchanger. “This is a very dangerous line of thinking,” said Lee Brooks from Thompson. “We follow the guidelines set out by the American Gas Association. Any visible crack or hole discovered in a visual inspection is reason for requiring replacement of the heat exchanger or furnace. This document is available on the AGA website.”
Another argument made is that scam artists use people’s reasonable fears of CO poisoning to trick them into unnecessary purchases. There have been cases of scam HVAC maintenance men informing homeowners that their heating system’s heat exchanger is cracked and as a result a new one, or a new furnace, must be purchased immediately to prevent possible death. Although this may be a scare tactic used by a small amount of scamming servicemen, cracked heat exchangers are a real threat and should be taken seriously. If any customer has suspicions about the serviceman’s findings, call another HVAC company and ask for a second opinion, but do this right away. Putting this repair off could be a life threatening decision. “At Thompson we have mandated each crack or suspected heat exchanger failure is looked at by a senior technician,”
said Lee Brooks. “We do a second opinion 100% of the time to verify if there is a failure. And we use an infrared camera that makes it very easy for the client and the technician to see inside their heat exchanger.”
Any homeowner who is informed that their heat exchanger is cracked or otherwise damaged must take that information seriously. A visual confirmation of the crack should be demanded; knowledge of how the crack was found likewise requested. Once the crack or other problem has been verified, it is urgent to take steps to prevent any chance of CO poisoning.