Fire and safety experts are reminding home owners and others -- especially those who've stepped up wood burning to help offset the rising cost of fossil fuels and colder-than-normal weather -- to make sure the chimney and fire box are indeed heaters and not hazards.

The California Real Estate Inspection Association says more problematic fireplaces and chimneys need special attention.

For starters, hire a trade-certified chimney sweep, licensed home inspector experienced in chimney, fireplace and wood burning stove inspections, a licensed general contractor or other professional experienced in looking into the firebox and up and down the flue to spot cracks, obstructions in the chimney, creosote build up, building code failures and other conditions that could turn a warm hearth into a tragic conflagration.

The inspections along with a good mechanical cleaning also help prevent conditions that contribute to carbon monoxide build up, which can be just as deadly as a fire.

Offering a host of related safety tips, chimney sweeps' trade group, the Chimney Safety Institute of America (CSIA), founded by the National Chimney Sweep Guild, advises getting your chimney swept and inspected at least once a year or more often, say, after you burn a cord of wood if you go through more than a cord in a season.

Even if you don't always burn wood, but the chimney is part of the central heating system's ventilation system, periodic inspections and cleanings are warranted, the institute says.

If you live in shaky, earthquake-prone regions or have recently experienced a natural disaster that could have undermined the structure of your home, a chimney inspection is in order.

"Chimney fires do not occur in clean, intact, properly installed chimneys," advises the a Hearth, Patio and Barbecue Association.

It's not just the flue and the firebox that needs a once over. New Environmental Protection Agency (EPA) certified wood burning stoves' catalytic converters, hoppers that feed pellet stoves and other mechanical components may need attention too.

Burning manufactured logs infused with chemical cleaners can help cut down on creosote build up. Chimney sweeps actually use chemicals found in the logs to break down the chemical composition of gunky creosote and render it easier to remove. The logs alone, however, are not enough.

"CSIA believes that the optimal method for cleaning a chimney is by a mechanical brushing of the chimney in conjunction with a complete evaluation of the system by a qualified chimney professional," CSIA advises.

CREIA recently issued an alert about more problematic components of some wood burning systems.

  • Metal Chimneys. Metal chimneys typically consist of two sheet metal shafts, one within the other to prevent the outer surface from becoming hot enough to start a fire in your attic. The temperature of the air between the two chimney walls can be extremely high and must be vented into the open air above the roof line. If the top of the outer chimney wall terminates inside the attic, heated air can singe wood framing and lead to combustion. Metal chimneys typically come with specifications for installing them so the clearance is at least one or two inches and never coming in direct contact with combustible materials.
  • Pre-Cast Fireplace. A pre-cast fireplace or fire place insert is made of a single pour of concrete at the factory and delivered to a construction site in one piece. The insulation plate can be the most problematic component because, at only two inches thick, a crack will allow heat and smoke to pass into the wall area creating a fire potential. Even when there are no signs of other damage to the fireplace, the insulation plate may have failed.

CREIA also says calcium chloride added to the concrete during assembly can react with the steel reinforcement and cause vertical and horizontal cracks in the structure. Repair costs for such problems are so prohibitively high, replacement is usually advised.

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