See the Pilot Light? Proper Ventilation of Exhaust Gases Is Crucial to Indoor Air Quality

When homeowners think about proper ventilation of exhaust gases, their gas stove is often top of mind. That’s because over the past 10 years research has strongly suggested that the negative health aspects of unvented exhaust gases – or emissions from aging appliances – is a detriment to indoor air quality.

The smell and taste of natural gas is distinctive. This is in part due to its chemical composition which includes minute amounts (<1%) creating sulfurous odors. The gas is made up of fossil fuels such as ethane, propane, butanes, as well as molecular heavy hitter hydrocarbons like naphthalene, commonly known as mothballs.

Those constituents come with negative health aspects that have been strongly linked to respiratory disease, particularly in children and the elderly. Despite the critical nature of the warnings, homeowners have been slow to change. Here are some examples:

Is your stove vented to the outside? 

Many homeowners with gas stoves don’t have exhaust hoods or fans. A 2015 study by the California Energy Commission of over 5,000 homes found that more than half of them (51%) had no exhaust hoods or fans. A 2016 study conducted for the Air Conditioning, Heating, and Refrigeration News (“AH&RN”) showed that 79 percent of surveyed homeowners said they either didn’t have or didn’t know if they had an exhaust fan over their stove.

That means that an estimated 100 million American homes are cooking with gas stoves without venting the exhaust gases to outside. A recent article by the World Health Organization stated that “the most important environmental risk factor for respiratory symptoms.”

In some cases, existing hoods and fans simply recirculate the air (and pollutants) back into the room rather than venting it outside. That isn’t just a problem with energy efficiency. It also contributes to poor indoor air quality that many people are unknowingly breathing. According to the AH&RN survey, “many homeowners have no idea” they are recirculating pollutants back into their homes when using stove top exhaust fans.

Recirculating air isn’t the answer either. 

A study by New York State’s Department of Health found that among  households with unvented gas stoves, those that had a hood or fan recirculating air were three times as likely to suffer from respiratory disease (by the time they were age 14) than those with vented systems.

Let’s assume there is an exhaust hood. The performance of hoods varies widely, many capturing only a meager 15 percent of emissions, depending on positioning and airflow. Vent hoods whose vent fans are connected to twisting lengths of vent ducts may face difficulty when it comes to moving cooktop gases out of the building. Still another blockage to exhaust flow is encountered at the exterior of the building at the vent/flapper if it is stuck in a closed position. 

Variables at play that are just as bad.

At this point, there are many vents and many variables that can affect how much air leaves your house with each sweep of your range’s fan. Now, let’s add an additional variable:

• The homeowner doesn’t turn on the vent fan switch. Just as you miss 100% of the shots you don’t take (thank you, Wayne Gretzky),  the vent system fails 100% of the time when people don’t use them — they find them noisy or distracting, or just forget.

Have you considered how all of these can impact the air quality in your home?

• Look at the gas appliance’s best friend, the pilot light. One tiny pilot light, always on in a ventless gas log set, adds exhaust gases to a room during every minute, day and night, all season long.  Believe it or not, this small pilot light can be far more dangerous than a one-hour cooking session at the gas stove twice a day.

• Same with a gas fireplace. For every hour, the pilot emits 0.4 milligrams of carbon monoxide. In 24 hours, that is 96 mg of carbon monoxide inhalation, and in 365 days, 3048-plus mg’s. That’s a lot. If all your home’s primary heat originates from gas appliances, you need to be aware of this healthiness risk if not already.

And consider, these possible scenarios:

• The vented log set but with the closed fireplace damper. 
• The gas water heater housed in the same closet as the HVAC air handler. 
• The HVAC gas furnace comes with its own combustion and venting issues. 
• The gas water heater also needs venting. 
• So does the gas-powered clothes dryer. 
• Other folks heat the basement with a wall mounted gas heater.

Over a day, improperly vented exhaust gases build up, eroding indoor air quality as well as home health and safety.

Now, not to be a spoil-sport, but some folks are avid candle burners, others prefer incense. Love that old kerosene heater? Or how about the gas generator outside? too often placed in a spot where drafts bring its exhaust gases into the house. Every little bit adds up. If you or a family member has been suffering health issues, you could be suffering needlessly. 

When it comes to exhaust gases, proper ventilation is crucial to indoor air quality. If you’re not sure about emissions, you’ll want to address any issues with your home appliances  as well as install a gas sensor as your first line of defense. If you’re in the process of upgrading or changing out systems, be sure and talk to your installer or contractor about air circulation. And, remember INSTALL Carbon Monoxide detectors. They’re just as important as smoke detectors (and Spring Forward/Fall Back is a great time to check the batteries if needed). 

And, if you’re not sure if indoor combustibles are eroding your family’s health and your home’s safety? We can help.