Nothing says home more than a fire crackling in a hearth.

Fireplaces have been a central feature in homes for centuries, but their design, technology and fuels have changed dramatically, especially in the past 10 years. Flames sprout out of torches or tureens; slip along a linear path through sand, stones or crystals; or blaze at temperatures hot enough to consume all the combustible material.

A growing number of realistic electric fireplaces or new no-vent gas products can add a touch of warmth or just the mesmerizing flicker of flames to almost any space, even apartments and mobile homes.

As higher fuel prices have consumers looking for ways to trim heating bills, many homeowners are looking at their existing fireplace as a more cost-effective source of extra heat.

"While fireplaces of the past were widely used for ambiance, many of today's hearth products are very energy efficient and can help cut energy bills," observes Jack Goldman, president of the Hearth Patio and Barbecue Association (HPBA).

Shipments of energy efficient fireplaces, stoves and inserts to retrofit existing fireplaces increased dramatically in the first six months of 2008 over the same period in 2007. Changed too are the number of options and anyone looking to upgrade an existing fireplace or add a new one is likely to be overwhelmed by the number of choices.

"It's not simple like it was 20 years ago," when there were a couple of wood and gas burning fireplaces and wood stoves, says Bob Martin, owner of Monroe Fireplace & Stove in Monroe, Wash.

Fuel sources, size of the firebox, heat or no heat, exterior finishes, classic, contemporary or country are only a few of the decisions consumers have to make.

Gas is the most popular fuel today and 70 percent of hearth products burn gas. With glowing embers, coals, even crackling fire sounds many gas units replicate wood fires. In fact some designers specialize in this.

For example, Walter Moberg, a custom designer whose work includes fireplaces for the Ritz Carlton ( MAR) in Atlanta and the Grand Lodge at Disney Grand California Hotel ( DIS), has a gas unit with several burners built into the grate as well as electronics that control the fire sequence so it follows the same pattern as a wood fire going from a small fire to a bigger one and finally to glowing coals. The cost for the entire fireplace starts at $50,000 and can top several times that amount.

Traditional fireplaces remain the top choice for consumers, but unlike their drafty ancestors, fireplaces today are 60 to 99 percent efficient depending upon the fuel source. Some even are certified by the Environmental Protection Agency, and most have a way to enclose the fire using insulated doors, with price tags ranging from $3,000 to $5,000.

This year, for the first time, an open wood-burning fireplace, the Renaissance Rumford 1000, won the Vesta Award, the industry's highest honor, for technological innovation. It is based off one of the earliest energy efficient fireplaces, introduced by Count Rumford in the 18th century. The original Rumford had angled sidewalls in the hearth that reflected heat back into the room and a flue design that encouraged a draft that directed more smoke up the chimney instead of into the room.

The Renaissance Rumford 1000, which retails for about $6,500, has an innovative guillotine door that is concealed when raised and seals off the fire when lowered. According to the manufacturer, it burns so cleanly that there is no visible smoke in the chimney only two minutes after the initial spark.

Almost 75 percent of new fireplaces are factory built and engineered. With prices in the $5,000 range, they cost a fraction of a masonry fireplace's building cost. Essentially, factory built fireplaces are a steel or cast iron box enclosed in a steel cabinet. Air circulates between the inner and outer boxes transferring the heat to the room and keeping the outer wall relatively cool. A traditional chimney isn't required, and depending on the fuel, some models can be directly vented to the outside using a small pipe.

Recently a number of manufacturers introduced vent-free gas models. The secret to their design is new catalytic technology that cleans the hot air before it leaves the combustion chamber.

"The thin design allows easy installation almost anywhere a gas line is available. No special framing is required," states Robert Dischner, direct of product development for Lennox Hearth Products.

Factory built fireplaces burn wood or gas and typically are designed to specifications for one fuel or the other. However, a gas log set can be added to most wood burning fireplaces. A gas log set consists of either a natural gas or propane burner covered in "firewood," fake logs made from a fireproof material such as refractory cement, ceramic clay or fibers and can mimic many varieties of wood, even driftwood.

Older existing fireplaces both masonry and factory built can be made into an efficient heat producer using a fireplace insert. Inserts are made from cast iron or steel and are similar to a freestanding stove. There are both gas and wood models and some are EPA certified. Unlike gas log sets, these products generate enough heat to warm one or several rooms.

In fact, Martin says, the biggest thing consumers don't know about fireplaces is how well they heat especially when it comes to gas units.

It is also not always easy to determine whether or not an existing fireplace can be converted into one that is more efficient. For factory built fireplaces, the type of fuel often determines what can be done with the fireplace.

"Builders today will put in a factory built wood burning fireplace with a nice set of gas logs and the builder will call it a gas fireplace," says John Crouch, director of Public Affairs for HPBA in Sacramento.

Retrofitting these units is relatively easy while a factory built gas unit will usually have to come out, he says.

Less efficient as heaters but easy to install are electric fireplaces which the industry describes as "plug and play" product. Many have flickering flames and glowing embers, a realistic firebrick backing inside the hearth and classic or contemporary facades and are even available at retailers and big box stores. They are priced as low as $300.

All that is required to light these fires is an electrical outlet although some models need to be hard wired by an electrician. Many produce heat and have the option of having the heat on or off.

Fireplaces and hearth products are so diverse that it' hard to make any generalizations but one thing is certain -- with thermostats, remote controls and flames that respond to a flick of a switch there is little resemblance to the days when starting a fire meant rubbing two sticks together.

Copyright 2008 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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