Forced air furnace without safety shutoff switch
Q. I read about a man who changed the filter in his furnace and didn't fasten the cover on the filter compartment. As a result, he reportedly died of carbon monoxide poisoning. This concerns me because I've had some trouble fastening the filter cover on my furnace and have found it detached on two occasions. If furnaces are so dangerous, how can they be allowed in homes?
A. The problem you read about probably involved a very old furnace that was installed in a closet and was manufactured before safety shut-off switches were required.
The filter compartment in a furnace functions as a vacuum chamber. It contains a blower motor that pulls air from the living area, allowing it to be reheated and blown back into the home. When the cover on the filter compartment is detached, air can be pulled from within the closet, and this can draw combustion gases from the burners and the exhaust flue, exposing occupants to poisonous carbon monoxide gas.
To eliminate this hazard, newer furnaces are equipped with a safety shut-off switch. When the filter access cover is removed, the switch is released, preventing operation of the furnace. If your furnace is able to work with the filter cover removed, you should contact an HVAC (heating, ventilation, and air conditioning) contractor to have a safety switch installed. On the other hand, if your furnace is too old to have a safety switch, the system may be in need of replacement.
It is also advised that your home be equipped with monoxide alarms, as required.
Q. As a heating and air conditioning contractor, I am routinely hired by a local home inspector to check heating and air systems. This inspector also subcontracts with an electrician and plumber for other areas of his inspections. Since no home inspector can be an expert in every trade, why don't more home inspectors hire subcontractors?
A. The functional purpose of a home inspector can be compared to that of a primary care physician. Each is there to perform a preliminary diagnosis. If problems are found, requiring further evaluation or corrective procedures, subcontractors or medical specialists are then recommended, as needed.
You are correct in observing that no inspector can be an expert in all aspects of a property. However, an experienced inspector should have a basic knowledge of the essential aspects of a home and should be able to determine when further evaluation and repairs by a subcontractor are warranted. For example, let's consider the forced air heating systems that you evaluate for your local home inspector.
A home inspector's evaluation of a forced air system should include functionality, signs of physical deterioration, installation of proper flue hardware, clearance requirements for fire safety, adequacy of the combustion air supply, proper fuel connections, symptoms of faulty combustion, prohibited locations, and much more.
If an inspector is not able to identify basic red flag conditions in the heating, plumbing, electrical, roofing, and foundation systems without hiring subcontractors, then the buyer should find a more qualified home inspector, rather than a team of specialists.
• To write to Barry Stone, visit him on the web at www.housedetective.com, or write AMG, 1776 Jami Lee Court, Suite 218, San Luis Obispo, CA 94301.
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