Why fireplaces work

By: John Kelly. 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. 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 ]. PROS Concentric pipes draw in outdoor air and expel exhaust gas. Natural gas or liquid propane fuels flames in a sealed chamber.

Ceramic-fiber logs glow without burning. The box reaches full heat in only 15 minutes. CONS Lacks the fun of the bellows, a poker and a smoky aroma. Tempered-glass-face temperatures approach F, a burn risk, especially for children. The manufacturer Lennox now offers free protective screens. Step one is to open the damper, Chimney Sweep Inc. The other common problem is insufficient updraft—try opening closed doors or windows in a room with a smoky fireplace.

Have the chimney swept annually, or as every two cords of wood are burned, Oyen says. Burn seasoned wood to slow creosote buildup. The time it takes for logs to dry out can be influenced by the time of year it was cut and the type of tree it was cut from. Wood from coniferous trees, such as Pine, is known as softwood, and typically takes a short amount of time to grow than hardwood trees.

The drying out process for softwoods can typically take anywhere from 6 to 12 months. Wood from deciduous trees, such as Oak, is known as hardwood, and is generally denser than softwoods because they can take a longer time to grow. Hardwood logs therefore can take a longer time to dry out compared to softwoods, taking typically years. The time of year the wood is cut will also dictate how long it takes for it to season. Wood cut during the winter months will typically have a lower moisture content than wood cut in the spring, and so may not take as long to dry out.

Whichever type of wood is burnt, to allow a fireplace to work as efficiently as possible the wood must be dry enough.

You can use a moisture meter to accurately read the moisture content of any logs before being used on a fire. Dry firewood , along with a clean chimney producing enough draft , and a good air supply from the room will give a fire what is needs to burn effectively and to produce the most amount of heat. Fires in open fireplaces are therefore built up to allow heat to be transferred to larger pieces of wood more easily.

Fires are typically built up with some sort of high combustible material, such as newspaper or firelighters, at the base of the fire, while small bits of wood known as kindling are laid on top. Finally, smaller sized logs can be added on top of the kindling to complete the fire. Lighting the newspaper or firelighters helps to transfer the flames to the kindling, which in turn causes the logs to start burning with more ease.

Burning wood that is too wet will hinder the whole process, as the wood will be harder to light and harder to burn. More energy is required by the fire to burn off any excess moisture content before it can start burning the wood effectively. An inefficiently burning fire can lead to incomplete combustion of the wood, which in turn can cause the fire to smolder and more smoke and creosote to be produced.

Ash from a wood fire will fall through the fireplace grate if one is being used onto the hearth into an ash pan. Many fireplaces have an ash dump located beneath the firebox to allow ash to fall through and collect. Ensuring that using wood that is dry enough is therefore an important aspect of having a fire in an open fireplace. You can find our current favorite moisture meter over on Amazon here. Options for upgrading a fireplace include:.

The National Fire Protection Association, the manufacturer of the fireplace, and the venting manufacturer all have certain guidelines for proper installation and all of them must be followed.

For instance, improper installation can occur if the chimney chase is left open in the attic and the insulators blow in cellulose insulation.

The insulation then travels down and the chimney chase traps the heat around the fireplace insert. The trapped heat near the insert causes the wood and other combustible material to start a fire.

Negative Pressure and Carbon Monoxide Many people aren't aware of the dangers caused by negative pressure and carbon monoxide. Unfortunately, they can be life threatening. Many homeowners seem to want to keep their homes as airtight as possible; they believe doing so will reduce their heating bills.

But oxygen is needed by more than just the people living in the home. Cooking devices, fireplaces, water heaters, and furnaces, just to name a few, also need oxygen. When a home is airtight, all of these devices fight for oxygen.

Adding to this issue are bathroom fans that remove 60 square feet of air per minute from the home. Many homes have more than one bathroom fan, and the strongest fans take out the air, pulling air even from the weaker fans and other devices. If a stronger bathroom fan begins to pull oxygen from the fireplace, carbon monoxide can also be pulled into the living area.

If the fireplace is pulling the oxygen, carbon monoxide can be pulled from the water heater.