How Your House Works: Fireplace

December 23, 2011 6:30 AM

Classic brick-and-mortar fireplaces aren't exactly hot these days, according to Joe LaVecchia of New Jersey's Abbey Hart Brick & Stone. "We used to sell a million firebricks a year in the 1970s," he says. "Now it's more like eighty or a hundred thousand."

It's not that the hearth's allure has been extinguished?it's a cost issue. Between the prerequisite concrete foundation and a mason to do the job, a traditional fireplace can cost $10,000 to $15,000 to install. Then there's efficiency. Typical fireplaces draw and vent interior air that a homeowner pays to heat with a furnace. The image of dollar signs streaming out of a chimney comes to mind.

The most common alternative today is the fuel-efficient, direct-vent gas fireplace. Carpenters can install the prefab firebox, which costs a fraction of a traditional fireplace. Still, nothing duplicates a crackling hearth. The old flame?fascinating and elemental?dies hard.

CHIMNEYS: THE INSIDE STORY

1. FLUE Smoke rises through ceramic flue liners in about 95 percent of brick chimneys, Tyler McClave of flue-maker Superior Clay says. Round models span 3 to 36 inches in diameter; rectangular flues get as big as 24 x 24. But a 12 x 12 square is typical, and two flues often run side by side in a single chimney.

2. SMOKE SHELF Wood smoke rises from the firebox and collects along the smoke shelf, a horizontal termination that prevents smoke from traveling downward from the chimney and into the house. Located about 8 inches above the top of the firebox, the shelf? has a concave surface that collects rainwater and debris.

3. DAMPER The metal door atop the firebox closes when the fireplace is dormant to seal the drafty chimney from the home interior. It's not a perfect seal, McClave says, because a refrigerator-style rubber gasket can't last in intense heat. Common-sense note: Never light a fire with the damper closed.

4. FIREBRICK Also known as refractory brick, firebrick has an inherent ability to expand and contract with rapid heating and cooling. Face brick, which clads chimneys, cracks and fails when used to line a firebox.

Source: http://www.popularmechanics.com/home/improvement/interior/how-your-house-works-fireplace?src=rss

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