January 9, 2019

Every morning in households around the world, there is a sound. Between the sizzle of eggs being cooked on the stove and the roasting of fresh coffee, heating water, or a running furnace, you can hear it. The sound of burning fossil fuels. 

Burning fossil fuels in homes has become a necessity created by gas-fired combustion appliances like furnaces, water heaters, and gas ranges. Yet while these modern luxuries make life easier, they come with a price. Whenever fossil fuels are burned, harmful byproducts are created which can have deadly effects if not properly vented outside the house. Anyone who has these types of appliances should have a professional inspect them to ensure their home is as safe as possible. 

A Bit of Chemistry

Let’s start with some basic chemistry. To burn natural gas (AKA methane), you need oxygen. And the result of this burning creates a love triangle of carbon dioxide, water, and heat. But this process is often not perfect.  Unless your house is the Harvard University chemistry lab, chances are the gas that arrives in your house isn’t pure methane. There will always be contaminants. In most cases, burning gas results in Incomplete Combustion, due to the fact that the air is not pure oxygen. The oxygen used for combustion comes from the air inside your house, and oxygen only makes up about 21% of air. Since the process is using neither pure methane nor pure oxygen, the outputs won’t be only carbon dioxide, water and heat. Incomplete combustion is dangerous because it produces carbon monoxide (CO), an odorless gas that even in small quantities has damaging health effects. Symptoms of CO poisoning can be fatigue, headache, dizziness, vomiting, and in large doses can lead to unconsciousness, brain damage or death. 

All combustion appliances in your home produce CO, which is vented outside. Problems occur when the vents for these appliances’ backdraft, allowing CO and other gases to flow back into the house instead of outside. But CO isn’t the only risk associated with combustion appliances. Natural gas is fed via fuel lines which can be damaged or wear out, leading to interior gas leaks.  

Natural gas, while called “natural”, isn’t so innocent. This hydrocarbon can be incredibly harmful, leading to sickness or possible death from inhalation, and in certain concentrations cause fires or explosions. By now, I hope that you are convinced using flammable gas inside your home could be dangerous.

Now that we know the innate dangers of combustion appliances, what can be done to mitigate the risks without going back in time to the cavemen era? Simply having a qualified professional inspect your combustion appliances can alert you of current or potential problems. When these professionals perform an inspection, they carry several instruments specifically tuned to detect CO in the air and diagnose problems with gas pipes and appliances. 

Testing and Inspecting

Your Combustion Appliance Zone (CAZ), the room or area where you will find your furnace and water heater, must be clean and free of flammable materials. Only then can the inspection begin. The inspector will begin by checking all gas lines in reference to the home for leaks using a combustible gas detector. The instrument senses tiny leaks that may go undetected under normal circumstances.  These leaks are identified and labeled for correction. Next the inspector creates a ‘worst-case scenario’ for combustion equipment that encourages it to fail. By turning on all fans including furnaces, bath exhaust fans, and range hoods, a significant difference in pressure between the inside and outside is formed. This difference tells the inspector which condition the most negative pressure at each combustion appliance is. Once the condition is determined, the inspector tests each appliance to see if they backdraft or produce excess levels of CO. Depending on the results, the inspector will recommend a course of action.

If any appliances do fail the inspection, there are corrective steps that can be taken. Leaking gas lines can be repaired or replaced. With appliances there are different solutions based on the type of problem. One improvement may be to bring in combustion air from the outside and seal off the CAZ. This may involve as little as replacing a louvered door with a solid one that is gasketed, or as complicated as building a new room around the equipment. The CAZ essentially becomes outside the living space, and risk of CO poisoning is reduced. 

Another solution is to replace the appliances with sealed combustion power, direct vent or electric models. Without the use of gas appliances, there is no risk of CO poisoning.

Fortunately, the current market offers many sleek electric appliances with the highest rating of efficiency.  

Having your gas-fired combustion appliances inspected is not only a smart thing to do as a homeowner but is a requirement under Georgia Power’s Home Energy Improvement Program which allows customers to earn rebates for energy saving improvements. Additionally, it is mandatory for any green building certification program. 


Burning fossil fuels has become a necessary evil in today’s world. Producing carbon monoxide, even in small doses can be deadly. Every home should be equipped with low-level CO detectors on each floor to aid in alerting residents of potential threats. Beyond installing detectors, if there are combustion appliances in your home, the best route to long term home and occupant health is to have a qualified professional inspect them. This will ensure your home is healthy and safe, allowing it to be the peaceful sanctuary that a home should be.