What Causes Carbon Monoxide Leaks?

RTAblog_2012_1210_COdetectorAtlanta reporters spent the last week covering a carbon monoxide (CO) leak at an elementary school. First responders found five or six people unconscious and fifty people were sent to local hospitals. Gas appliances are common, especially in homes, so we need to take the simple steps to protect ourselves.

Carbon monoxide (CO) is a colorless, odorless gas that causes sudden illness and eventually death when inhaled. CO is common in combustion fumes from gasoline engines, gas stoves, gas furnaces. It’s also released by burning charcoal and wood.

CO can build up in our houses because we don’t have enough ventilation – our air conditioners typically don’t provide ventilation. Air conditioning systems can help spread CO through a house. That appears to be what happened in the school covered in the news reports – a problem with the boiler caused CO to build up in closed spaces and then spread to other spaces through leaks and the air conditioning system. Atlanta Fire Rescue reported a CO level “way, way higher than we’ve ever experienced before”.

The Centers for Disease Control has a carbon monoxide fact sheet that reports more than 400 people die from accidental CO poisoning each year. So how does a house that has no carbon monoxide suddenly have high levels of carbon monoxide?

People don’t just die from accidental poisoning because they left the stove on. We’ve found broken equipment that can cause carbon monoxide poisoning. The pipe on the left-hand side of the water heater (the white tank) in the following image is the flue (pronounced “flew”) pipe. It’s supposed to carry combustion gas from the top of the water heater into a pipe system that vents the gas to the outside of the house. It’s detached from the top of the water heater and the flue pipe to which it was connected so it’s just hanging on the side of the water heater.

RTAblog_2012_1210_WaterHeaterFlue

The water heater is still working – it’s still burning natural gas to heat water for the house. With the detached flue pipe, the water heater is now exhausting its combustion gases, including carbon monoxide, from the top of the unit into a closed crawl space. The crawl space is not sealed off from the rest of the house so the CO can build up and spread into the living spaces of the house.

In this house, both the water heater and the furnace burn natural gas to create heat. The flue from the water heater was connected to the flue from the furnace. As you can see in the following image, when the flue from the water heater fell off, it opened a hole in the flue from the furnace – now both devices are venting combustion gases into the house rather than exhausting them outside.

RTAblog_2012_1210_HVACflue

The following is an image of the top of the same flue pipe where it pokes through the roof of the house to exhaust the combustion gases. The protective cover on the top of the pipe was intended to keep rain and rodents from entering the flue pipe while still allowing the combustion gases to escape. When the cover at the top corroded and detached, it fell down on top of the flue pipe. That restricted the flow of combustion gases and caused them to back up in the flue and spread through the house.

RTAblog_2012_1210_TopOfFlue

We also have combustion gases build up in our houses by burning natural gas and wood in our fireplaces without a properly functioning chimney. The chimney may be blocked by a bird or squirrel nest, soot in the chimney flue, a broken damper or some other problem. Since we can’t smell or see carbon monoxide, it’s critical to install CO detectors.

The advice we give is never, ever, ever rely on one carbon monoxide detector. The work of a functioning CO detector is too important to have one fail without you knowing it. CO detectors should always and at the very least be used in pairs – though we prefer more in big houses where the equipment is spread out. You can locate them close to sources of carbon monoxide. We already know where the combustion devices are so take the necessary steps to protect yourself (and your family).

You can also purchase a CO detector from most hardware and grocery stores. They’re well worth the investment! The CO detector in the image at the top of this post is part of a monitored alarm system. The hardware is not much more than you’d pay for a stand-alone device though you get the benefit of a monitored detector – if the alarm system siren doesn’t wake you, the police response will.

Carbon monoxide detectors connected to a central alarm system are particularly important when parents are sleeping in a room on a different floor than the sleeping rooms of their children – parents sleeping in a downstairs bedroom may not be able to hear the siren from a stand-along CO detector on another floor or in the attic.

We encourage you to share the CDC guide on carbon monoxide (more resources than the fact sheet). It has some great points about the risks of CO poisoning increasing after a disaster. As you’ve seen, it’s also critical to properly maintain your equipment. Please consider giving CO detectors as gifts – they’re a gift of safety and peace of mind!

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  1. Pingback: 2013: The Year Ahead for Building Codes in Georgia | Ryan Taylor Architects LLC

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