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    Gas Furnaces and Carbon Monoxide Awareness

    While there are several choices for heating your home, natural gas furnaces help 47% of American households keep their home environments cozy and warm all winter long. While electric heating is popular in mild-winter areas, natural gas and, in very cold areas, oil, provide economical, comfortable heat.

    While most consumers don’t think anything of flicking the switch from “cool” to “heat” as the seasons turn, savvy homeowners should ensure their furnace is in top condition with an annual inspection and regular maintenance.

    That’s because carbon monoxide (CO) is a natural product of the process of burning fossil fuels such as oil or gas using combustion. Without proper installation and upkeep, furnaces and carbon monoxide can be a deadly combination for homeowners — and for technicians, HVAC professionals, and home inspectors responding to service calls.

    Gas Furnaces and Carbon Monoxide — The Basics

    Unintentional deaths from carbon monoxide (CO) poisoning are highest in the winter, partly due to faulty furnaces and generators. In fact, according to the Consumer Product Safety Commission, 900 people died from CO poisoning from furnaces between 2005-2017, with gas heating equipment accounting for the largest numbers of deaths.

    The Potential Hazards of Carbon Monoxide (CO) from Gas Furnaces

    Gas furnaces heat through combustion, producing exhaust gases which, in a properly installed furnace, stays mostly within the heat exchanger — a metal tubing or wall that heats up when burners are ignited. Typically, the gas is forced through the flue pipe of your furnace and vented safely to the outside of your home.

    Initially, a gas furnace produces small amounts of CO, but if it is not properly maintained, it can begin to burn “dirtier,” emitting larger amounts of CO.

    Contributing to the issue are today’s modern “tight” homes that are built to be energy-efficient — and airtight. An airtight home means one in which outside airflow is restricted, a process inhibits CO from dissipating in situations where a gas furnace is improperly installed or experiencing issues.

    Here are some issues that can contribute to CO buildup caused by your furnace:

    • A cracked heat exchanger — Because the furnace heat exchanger is made of metal that contracts and expands as your furnace turns on and off, it can crack after many years of use. For severely cracked heat exchangers, it is possible for CO to leak out of the exchanger and into your environment.
    • Plugged vent pipe or chimney – For a natural vent furnace, an obstruction in the vent pipe or chimney can prevent exhaust gases from rising up and out properly, causing CO and other fumes to be released into the home.
    • Incorrectly installed exhaust piping – If the exhaust piping has a horizontal or downward slope, multiple bends, or diameter reduction, it can result in the exhaust gases being released directly into the room.
    • Insufficient combustion air – When a gas furnace is installed in a small room without proper door vents (i.e., one on the top of the door and one on the bottom of the door), there will not be enough fresh air for proper venting.
    • Low or negative indoor air pressure – When exhaust fans and dryers are pushing air out of the home, there is a potential for low indoor air pressure which can create a back-draft of the gas furnace exhaust. Essentially, the combustion fumes from the furnace will be sucked back into the home.

    Signs there may be a venting issue:

    Besides a cracked heat exchanger, clogged or damaged furnace flues represent another risk of CO poisoning for natural vent furnaces. Here are some ways to detect — and prevent — this issue:

    • Rust streaking on the flue, chimney, or vent
    • Condensate on the flue, chimney, or vent
    • Soot build-up around the furnace
    • White residue on the chimney brick that indicates leached mineral salts due to increased moisture
    • A change in flame color from blue to yellow

    When there is a carbon monoxide issue related to the furnace or venting, there is a potential for the carbon monoxide levels to climb to high levels relatively quickly throughout the home, especially for forced hot air systems. Forced hot air systems will bring air from certain locations within the home to the furnace to be heated and the redistributed throughout the various rooms in the home. Furthermore, if the basement of the home is finished, heated and close to the furnace room, the furnace could potentially bring return air from the finished basement and redistribute the high concentration carbon monoxide gas to the rest of the home very rapidly.

    Installing a CO detector is your first-line defense against typical CO-producing issues with your gas furnace. However, if you see these warning signs, call an HVAC professional to perform an inspection and maintenance.

    Using Carbon Monoxide Meters to Detect and Monitor Carbon Monoxide Levels (Generic Across all Industry/App Pages)

    The Sensorcon Inspector is a trusted tool used by HVAC professionals and home inspectors for detecting and identifying sources of carbon monoxide leaks.

    Low-to-moderate carbon monoxide (CO) levels in the common areas of the home are indicative of a leak source inside the residence. After ruling out possible outside sources of carbon monoxide, for example a car running close to an open window or in the garage, the professional can use the Sensorcon Inspector to check the furnace, boiler or other home appliances (e.g. gas water heater or stove).

    Higher carbon monoxide (CO) levels in the common areas of the home may be indicative of a problem with the furnace or the venting, especially for forced hot air gas furnaces.

    Depending on the concentration levels of CO within the home, the HVAC professional or home inspector can take appropriate action, including disabling the furnace until the equipment can be repaired or replaced.

    The Sensorcon CO Inspector is a portable and reliable carbon monoxide meter (CO meter) that was designed in the USA and assembled in our manufacturing facility located in Buffalo, NY.

    The CO meter provides you with real-time readings all the way from 0 to 2000 PPM and is used by professionals to monitor or inspect for carbon monoxide.

    Trusted by police, fire fighters, emergency medical services (EMS), home inspectors, plumbers, and HVAC technicians, the Sensorcon CO Inspector is a great tool for monitoring for and diagnosing CO leaks in the home or workplace.

    Please visit our product pages to learn more about our various product offerings.

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