Homeowner fears carbon monoxide
Q. We've seen a number of articles warning about the dangers of carbon monoxide and are wondering if we might be having that kind of problem with our forced air furnace. Lately, we've noticed an unusual burning smell whenever our heater is turned on. How can we tell if this condition is serious?
A. Carbon monoxide gas (abbreviated CO) is entirely odorless; therefore, it is unlikely that the burning smell you have noticed indicates that kind of problem. However, any questionable condition involving a gas-burning fixture should be regarded as potentially serious and should be called to the immediate attention of the gas company or a licensed HVAC contractor.
There are several possible circumstances that could be causing your furnace to emit burning smells. If the furnace has not been used for months, dust inside the system could be burning off. This is common and is not a cause for concern.
On the other hand, there could be hazardous causes such as an exhaust pipe in direct contact with the wood framing in your attic; leaves from nearby trees could have fallen into an open flue pipe on the roof; combustible items could have been stored too close to the furnace itself.
It is also possible that the flame pattern at the burners is reaching beyond the confines of the combustion chamber, a hazardous condition that can be caused by inadequate combustion air supply or congestion within the exhaust system. With congested exhaust, flame rollout can cause combustion gasses to vent into the dwelling, in which case carbon monoxide would in fact be a major concern.
Any one of the foregoing conditions could be the source of the burnings smells you have noticed, and most of these are hazardous. It is advised that you curtail further use of your heater until it has been thoroughly evaluated by a qualified professional.
It is also advised that you have functional smoke and carbon monoxide alarms near all bedroom entrances and on each level of your home.
Q. The home inspector who checked my house recommended a spark arrester for the masonry chimney. Since the fireplace is set up with gas logs and is no longer used to burn wood, is a spark arrester necessary?
A. In practical terms, the lack of a spark arrester is not likely to be a safety problem if you are only burning gas. However, a spark arrester is advised in case the fireplace is restored to wood-burning use. The fact that you just had a home inspection indicates that your home is probably in escrow. In that case, it is possible that the buyers might intend to use wood logs, rather than gas logs.
If conversion to wood-burning use should ever take place, the installation of a spark arrester could be inadvertently overlooked at that time. Therefore, adding a spark arrester now will ensure against this potential fire hazard.
Fortunately, the addition of a spark arrester is neither complicated nor expensive. All that is needed is a piece of half inch hardware cloth (wire screen) and a qualified chimney expert to install it properly.
• 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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