Do you love sitting by a fireplace? Does a crackling fire define a home to you? If so, you're not alone. In a survey conducted by the National Association of Home Builders, 77 percent of home buyers said they wanted a fireplace in the family room [source: Fireplaces.com]. The indoor fireplace is a technology that dates from the Middle Ages, when people in medieval castles and homes used them for warmth. However, traditional fireplaces today are desired more for their aesthetics than to be used as effective heating appliances. Even as far back the 18th century, Benjamin Franklin noted that "the strongest heat from the fire, which is upwards, goes directly up the chimney and is lost" [source: Carlsen]. And Franklin was right. The standard fireplace is among the most inefficient heating devices you can operate. In fact, it can be so inefficient that in some cases it actually makes your house colder. Inefficiency is not their only drawback. In addition to the risk of setting the house on fire, the smoke that ends up inside your home can contain harmful chemicals, which is a problem in tightly sealed modern homes. And although many modern fireplaces use renewable fuel, they're not considered completely "green," because they can add to air pollution. But it's not all bad news for fireplaces. Improvements have given fireplace fans a range of more attractive alternatives. Better designs provide more heat, less waste and safer operation. If you're willing to give up the smell and glow of burning wood, a direct-vent, gas-powered fireplace can be an efficient heat source that may even save you money on fuel. In this article, we'll look at how a fireplace works and how to operate it safely. We'll also consider some innovations that allow you to have a fireplace without a chimney, on your patio or on the coffee table in your living room. The Parts of a Traditional FireplaceTo understand how a traditional fireplace works, you'll need to know about its various components:
The Mechanics of the Traditional FireplaceLighting a fire inside your living room presents two obvious challenges. First, you have to avoid setting your house on fire. Second, you need to keep the smoke from spilling into the room. A fireplace solves both difficulties. It is made from materials that don't burn (traditionally, stone and brick, but also metal and tile), and it takes care of smoke by sending it up the chimney. The most important mechanical function of a fireplace is to generate a draft. If you think of a hot air balloon, you know that a mass of heated air rises. A fireplace creates a column of heated gas inside the chimney. As that air rises, more heated air from the fire is pulled after it. The result is a draft -- a steady flow of smoke and hot gases -- up the chimney. The draft serves another purpose, too. Any fire needs a steady flow of oxygen to keep burning. As the hot gas rises, it pulls fresh air into the pile of burning fuel. You might remember from physics class that there are three methods by which heat moves:
But the principle of convection is also at work in a fireplace, and this is one reason why they can be so inefficient. The major portion of the heat that a fire creates is in the form of hot gas. Convection sends this gas up the chimney, where it is wasted. What's more, the draft can draw more warm air from inside the room than the fire needs to burn and pull that air up the chimney as well, leaving the room colder than before. Some experts say that traditional fireplaces can draw four to ten times as much air from the room than is needed to burn the fire [source: Carlsen]. Sometimes, more heat is lost through convection than is added through radiation, resulting in a fireplace's negative energy efficiency. The colder it is outside, the colder the air that the fireplace sucks in and the lower the efficiency. How to Operate a Traditional FireplaceOperating a traditional wood-burning fireplace is not difficult if you follow a few simple guidelines. First, you should begin by choosing the right fuel. Be sure to burn hard woods, such as hickory, ash, oak and hard maple. Soft woods such as pine and spruce generally don't burn as well or provide as much heat. Also, be sure your wood is seasoned, or dry. Wood needs at least six months -- many experts suggest at least a year -- of drying to reach the 20 percent moisture level that is recommended for a good fire [source: Taylor]. One way to be sure your wood is seasoned is to knock two logs together and listen for a hollow sound, not a dull thud. Seasoned wood is also darker and has cracks in the end grain. Avoid using wet or rotten wood, and never burn trash or cardboard in your fireplace. Pressure-treated wood and chipboard are also inappropriate. To start the fire, you need kindling -- smaller pieces of wood that will take flame easily. Stack a few split logs on your grate and place kindling around and below them. Make sure the damper is open before you light the kindling with newspaper. Don't use too much paper, as flaming scraps can be carried up the flue and onto your roof. Never use gasoline, lighter fluid or a butane torch to start a fire. Once the fire is burning, you may still encounter problems with puffs of smoke entering the room. One cause of a smoking chimney is a house that's too tight. If there aren't enough openings to make up for the air drawn up the chimney, it can cause negative pressure in the room, creating a partial vacuum. Air pressure forces air down the chimney to compensate, resulting in a smoky house. The solution is to crack a window near the fireplace to let air in [source: HGTV]. Here are some other points to keep in mind:
Improving the Efficiency of a Traditional FireplaceThere are two main strategies for improving fireplace efficiency. The first is to use convection as well as radiation to capture some of the heat from the fire. Some fireplaces include a built-in heat exchanger -- channels where room air can circulate around the hot parts of the structure -- either through natural air flow or forced by a fan. The air absorbs the heat and returns it to the room. The second approach is to block part of the front of the firebox in order to limit the amount of air that flows unnecessarily up the chimney. Usually, this is done with doors made of tempered, heat-resistant glass. Adjustable inlets allow enough air to reach the fire to keep it burning. Here are some specific ways these two strategies are used:problem is that much of the heated air is drawn back into the fire. Used with glass doors that block this air return, a tubular grate can help squeeze more warmth from a fireplace [source: Ace Hardware].
Glass doors reduce the loss of room air up the chimney and still allow you to view the fire. The drawback is that the glass can also reduce the heat that reaches the room by half (even a mesh screen reduces radiant heat by 30 percent) [source: Bortz]. The result is a small gain in efficiency. Fireplace inserts are metal boxes -- usually equipped with glass doors -- that fit inside the firebox. They use a heat exchange chamber with channels to allow room air to pass through and absorb heat. Fireplace inserts usually require a full stainless steel flue liner, rather than simply connecting to an existing flue. An insert can put out up to five times as much heat as an open fireplace [source: Carlsen]. Some homeowners prefer to take advantage of the efficiency of a wood stove by placing the stove on the fireplace hearth and running the stovepipe into the fireplace chimney. By doing so, they lose the pleasures of an open fire but gain energy efficiency. Now that you understand the workings of fireplaces, you might be interested in reading more about modern, eco-friendly, heat retaining fireplaces such as Austrian Ceramic fireplaces that are designed and built into beautiful modern designs but companies such as Designer Fireplaces in Cape Town. For advise on what design will work best for your home contact them by visiting their website on www.designerfireplaces.co.za. Orginal Source of Information: https://fireplacescapetown.wordpress.com/2016/04/06/how-fireplaces-work/
2 Comments
17/11/2020 09:07:55 pm
Intererested to know more about fireplaces maintenance..
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30/11/2020 03:03:08 pm
קמין חשמלי איכותי הופך כל בית ליפה יותר ונותן לו תחושה חמימה. תמצאו אצלנו קמינים מכל הסוגים.
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