Carbon-monoxide alarms are inexpensive and are a must for all homes.
"Two local residents overcome by carbon-monoxide poisoning."
This is the headline that all too often starts to appear when the heating season begins. Carbon-monoxide poisoning is often misdiagnosed as coldlike symptoms or the flu. If your cold or flu symptoms decrease when you are away from the possible source of the poisoning, you need to advise your employer if it's at your workplace or your utility company or fire department if it's your home.
Carbon monoxide (CO) is a colorless, odorless gas that is a byproduct of the combustion of fossil fuels. A clean-burning gas appliance has little CO off-gassing, but a partially blocked flue or a furnace or water heater in a confined space can be a major source of CO poison.
Even if the appliance worked perfectly last winter, the flue could have become blocked with nests or debris over the summer, and that could now block the flow of vent gases to the outside. These flue gases then spill back into the appliance, where they block the flow of oxygen to burners. Without a proper mixture of fuel and oxygen, the flames will continue to burn but very little heat will be produced.
However, CO is produced in large quantities from an improper gas-to-air mixture. The burners will have yellow flames, which do not heat properly, but will continue to burn because the thermostat is not reaching the desired temperature. Before operating a gas appliance, have the units checked thoroughly by a qualified contractor.
Make sure he does a venting test of the flue of the furnace, water heater and, if you have one, fireplace. The modern high-efficiency gas-fired condensing furnaces vent through a PVC plastic flue pipe and vent mostly moist air. Have the joints of the pipe checked and then watch for signs of drips or leaks every time you change the filters.
The constant expansion and contraction of PVC pipe joints may weaken them to the point of failure. It is imperative to have all flues checked annually.
Carbon-monoxide alarms are inexpensive and are a must for all homes. I suggest a model that has a digital readout with a memory. If the alarm sounds, the proper authorities would then be able to see what levels of CO triggered your alarm.
Sometimes weather inversions can hold CO emissions from automobiles traveling near your home. Those could trigger the home's alarm. Do not take chances if the alarm goes off. Take your pets and leave the home until the area is cleared by the fire department.
If you have a totally electric home with an attached garage, you should also have a CO alarm installed near the garage door to warn you of potential dangers.
Starting the car's engine with the door open does not mean fumes will vent to the outside. The cold outside air is rushing into the warmer garage, holding gas fumes inside the garage. They can seep under the door to the house.
If you must warm your car or truck in the morning, at least back it out of the garage.
(Dwight Barnett is a certified master inspector with the American Society of Home Inspectors.)