Hearthside

Even as recently as the early 1980s, residential fireplaces were much less common than they are today. Before then, the vast majority of serious wood burning, particularly for heat, was done with basement wood furnaces or simple black cast iron or plate steel wood stoves. Now, the wood-burning situation has changed markedly. Most new home woodburning appliances are efficient wood stoves and advanced fireplaces which are often able to provide much or all of the heat for a home while at the same time offering the beauty and atmosphere of a visible fire.A fireplace or wood stove offers security and peace of mind, as many fireplaces and wood stoves do not require electricity to function. In the event of a winter emergency or disaster, even if the power goes out, natural gas is typically available for many hours. If you have a wood burning fireplace or traditional wood stove, you may even be able to cook your food on a wood fire, transforming a potential catastrophe into a family adventure.

Medium wood stoves are suitable for heating small houses, medium-sized energy-efficient houses, and cottages used in winter.

Large wood stoves are suitable for larger, open plan houses or older, leakier houses in colder climate zones.

Fireplace Inserts
For people interested in enhancing the look and feel of an existing wood burning fireplace, the hearth industry has great news. It’s now easier than ever before to increase the efficiency of a fireplace by adding a fireplace insert. The installation of a fireplace insert can turn an occasional source of warmth into a convenient and easy-to-use supplemental zone heater that can help control high home heating bills while protecting winter air quality. Fireplace inserts are available in many fuel types, including gas fireplace inserts, wood fireplace inserts and pellet fireplace inserts. If you rely on your fireplace for added warmth on cold days, consider a fireplace insert. They are similar in function and performance to free-standing stoves, but are designed to be installed within the firebox of an existing masonry fireplace. Municipal installation codes now require that a properly sized stainless-steel liner be installed from the insert flue collar to the top of the chimney. The result is better performance and a safer system. You can choose from fireplace inserts that burn wood, pellets or gas that provide the same safe efficiency as their wood stove, gas stove or pellet stove counterparts. EPA certified wood burning fireplace inserts and pellet burning fireplace inserts are available. Some fireplace inserts include state-of-the-art features such as fans and thermostatic controls, depending on the fuel.

Pellet Stoves
Instead of logs, pellet stoves burn a renewable fuel made of ground, dried wood and other biomass wastes compressed into pellets. Pellet stoves are some of the cleanest-burning heating appliances available today and deliver high overall efficiency. Because they pollute so little, pellet stoves do not require EPA certification; some manufacturers, however, voluntarily seek this certification. Unlike wood stoves and fireplaces, most pellet stoves need electricity to operate, and can be easily vented through a wall, unlike woodburning stoves. Once you experience a pellet stove, it’s easy to understand why people rave about these efficient and unique home heaters that generate an automated, economical and earth-friendly wood heat…and all without firewood! For just pennies an hour, a pellet stove can deliver a deep, penetrating warmth that provides independence from high heating bills while emitting almost no wood smoke. And with tremendous flexibility in installation and sizing, pellet stoves are a sophisticated choice for convenient heat that helps protect the environment.

If you live in an apartment or condo and dream of cozying up by the fire, there is an ideal solution: an electric fireplace. The warm, radiant heat of today’s electric fireplaces can be installed in minutes. Simply plug the fireplace into an outlet and you’re ready to fire it up. Electric fireplaces are designed to be plug-and-play appliances, much like a stereo or a television. Simply turn them off and on as needed, and enjoy them when the mood hits! And with realistic fire technology that rivals a wood burning fire, the end result is snap, crackling great!

Electric Fireplaces

If you live in an apartment or condo and dream of cozying up by the fire, there is an ideal solution: an electric fireplace. The warm, radiant heat of today’s electric fireplaces can be installed in minutes. Simply plug the fireplace into an outlet and you’re ready to fire it up. Electric fireplaces are designed to be plug-and-play appliances, much like a stereo or a television. Simply turn them off and on as needed, and enjoy them when the mood hits! And with realistic fire technology that rivals a wood burning fire, the end result is snap, crackling great!

Yes, but open fireplaces give all fireplaces a bad name

Talk about a clash of technologies: In a house that is to be tightly-constructed and well-insulated so it will be cozy and easy to heat, the homebuyers want to have a traditional open fireplace, a device whose design was state-of-the-art a couple of centuries ago. Once built, this new house and old fireplace will not coexist without conflict and the owners might regret reaching back in history to select their fireplace.

To perform reliably in a modern house, the unruly traditional fireplace must be tamed by some new technology, but it need not lose the essential qualities that have always compelled us to gather around the hearth.

Declaring my bias, I freely admit my enthusiasm for fireplaces and think that every house needs a hearth to be complete. A fire burns on my hearth all winter and I never tire of watching the flames and being within range of their warmth.

That said, I also think the traditional open fireplace is headed for extinction and I, for one, won’t shed a tear at its passing. The end will come because the open fireplace is an antique technology that is incompatible with modern housing. It is wasteful by temperament, and through its gluttonous appetite for fuel and air, it scoffs at the ideas of energy conservation and environmental correctness.

If you build a standard house using the latest in materials and techniques, its tight skin will not leak enough to supply the air demands of an open fireplace. The problem is not with the house, but with the anachronistic fireplace.

Strong opinions, often colored by myth and misinformation, usually surround discussions of fireplaces. So, to avoid any misunderstanding, allow me to propose this basic principle: A fireplace should work well all the time and never screw up in a big way; should not belch acridly during a party, should not set off the smoke detectors at 2:30 in the morning, and should not stink and gush cold air when no fire burns. And further, given the advanced state of construction and fireplace technology, a builder should be able to confidently guarantee to the homebuyer that the fireplace will perform properly.

It is not much to ask, really, that a fireplace work properly, no more than we ask of most other building components. Yet, complaints about nuisance fireplaces are among the most common call-backs in the building industry. Despite the voodoo preached by proponents of certain variations on the theme, there is nothing magical about fireplace design. For example, here is a pretty reliable rule of thumb: the more air the fireplace demands for normal operation, the more susceptible it is to spillage and backdrafting.

If you place the fire on the room side of a flow restriction, like a throat damper, you need strong draft and high flow up the chimney to keep smoke from spilling into the room. An open fireplace consumes between 200 and 600 cubic feet per minute (cfm) of room air—more if it is a big fireplace with a big, big fire. Tightly built houses cannot tolerate a 200 cfm exhaust flow without getting meaningfully depressurized, so there’s a problem right away.

If a home buyer rigidly demanded an open fireplace, it could be made to work if you threw enough money and horsepower at the problem. A chimney top fan could be installed at considerable cost, but it could severely depressurize the house in its attempt to flow enough air to prevent smoke spillage from the fireplace, and would likely backdraft a conventional gas furnace or water heater. Alternatively, a high-volume, fan forced, pre-heated outdoor make-up air system could be designed and installed. Just before lighting the fireplace, the user would turn on the make-up air fan, pressurizing the house and forcing the necessary flow through the fireplace and up the chimney. This large-capacity make-up air system would be complicated because the incoming air would need tempering by a thermostatically-controlled electric duct heater of substantial output. Distributing the air effectively could also be a challenge. Both options—the chimney top fan and large make-up air system—are expensive and both have drawbacks.

There are easier ways to tame the fireplace. When you place the fire behind the main flow restriction, say a glass door assembly, you can get away with lower flow rates and draft levels without smoke spillage. With doors, even a set of leaky bi-fold doors, the flow rate drops by three-quarters to 50 to 150 cfm, depending on flue size, fire size and door leakage. The barrier between the fire and the room formed by the doors makes the fireplace more spillage-resistant by a huge margin. The doors don’t make this fire place an efficient heater, just less of a nuisance.

Some people claim that glass doors spoil a fireplace. (Do they mean in the same way electric lights spoiled the pleasure of reading by candle light? Or the way shock absorbers on cars took away the feel of the road?) In reality, at least a spark screen is needed to prevent damage to rugs, floors and furniture when the characteristic crackle of the fire spits glowing bits from the hearth. True, glass doors do block out most of the sound of the fire, which is just fine for those of us who find the crackle only makes them apprehensive about those glowing bits. Given the choice of looking through a wire mesh screen or clear glass, I’ll take the glass.

Beyond the open fireplace at 400 cfm average air demand and the fireplace with doors at 100 cfm, there is a third category in this descending order of air demand. Call it a controlled-combustion fireplace. It has doors with gaskets and it manages both the amount and location of combustion air it admits. By limiting the flow of air to an amount closer to that needed for combustion of the wood, the demand falls by three-quarters again to 15 to 30 cfm. Within this category, I would include all the factory-built fireplaces that meet the Environmental Protection Agency (EPA) emission limits for wood heaters, as well as massive heat-storage units like masonry heaters, Russian fireplaces and their ilk. There are also many controlled-combustion fireplaces that are EPA exempt, which, because they are fairly modest consumers of room air, can function well in tight houses.

Not incidentally, a fireplace’s consumption of room air directly affects its efficiency, that is, how much of the energy contained in the logs is transferred as cozy warmth to the room.  Because they suck up so much room air, open fireplaces deliver between zero and 20 per cent net efficiency.  The low efficiency results from the house furnace working so hard to heat up the outside air that must come in to replace air exhausted by the fireplace.  The colder the weather, the lower the delivered efficiency from an open fireplace.  A fireplace with doors can deliver between 10 and 30 per cent efficiency, depending on whether it has a heat exchanger that works, but this is still lousy efficiency by modern standards.  A fireplace that uses current technology, one that is EPA certified for low emissions, for example, will deliver between 60 and 70 per cent efficiency.  This means a modern woodburning fireplace is competitive with any other form of home heating in terms of energy efficiency.

Some housing technologists recommend that builders avoid using any heating or hearth appliance that vents through a chimney and operates on natural draft. This caution would apply to all wood burning fireplaces because, with current technology, they must be vented through a vertical chimney. While I’m sure such advice is well-intentioned, if adopted, it would mean the elimination the natural hearth from every new house. Home buyers could not enjoy the comfort and quality of a well-built modern home while sitting in their favorite chair in front of a real wood burning fireplace. They could not stay cozy and comfortable during an electrical power failure by burning wood in the fireplace. They would be unable to use this renewable energy source as one route to environmental responsibility, but would be forced to heat with fossil fuels and be locked into a one-sided relationship with a large energy utility. If they wanted a hearth, their only option would be a virtual fireplace burning gas or propane with its designer flame and mind-numbing sameness. Of course, gas fireplaces are fine for urban houses and apartments, but one of the great pleasures of living on the urban fringe and beyond is to build a real fire on a beautiful hearth and sit back to enjoy it.

A future of houses without real fireplaces is not particularly appealing. Luckily, it’s not necessary either. By matching technologies, it is possible to combine a modern house with a real fireplace. In specifying a spillage-resistant fireplace for a well-built house, the first line of defense is a set of glass doors. These must have panels of ceramic glass, a miracle material that won’t shatter, but will allow infrared (heat) radiation into the room.

Better still, select an EPA certified fireplace or a masonry heater from a reputable supplier. These units consume very little room air and can tolerate a modest level of room depressurization without complaint. They can be just as beautiful as a traditional open fireplace, but their manners are so much better.

Whatever your wood burning system, you can improve its efficiency and reduce air pollution by learning to burn correctly.

The knowledge and skills needed to operate a wood burning system effectively need to be learned and practiced to get them right. Although it is not brain surgery or rocket science, it is not as simple as it might first appear. So, when you can light a fire with a single match and get a hot, bright fire burning in just a few minutes, you’ve accomplished something worth knowing and we salute the time and care you’ve taken. Reach around and pat yourself on the back.

How does wood burn?

It is a complex process, but it can be divided into three stages:
The water evaporates: Up to half the weight of a freshly cut log is water. After proper seasoning the water content is reduced to less than 20 per cent. As the wood is heated in the firebox, this water boils off, consuming heat energy in the process. The wetter the wood, the more heat energy is consumed. That is why wet firewood hisses and sizzles and is hard to burn while properly seasoned wood ignites and burns easily.

The wood smokes: As the wood heats up, it starts to smoke. The smoke is a cloud of combustible gases and tar droplets. It will burn if the temperature is high enough and enough combustion air is supplied. When the smoke burns, it produces bright flames. If the smoke does not burn it will flow into the chimney where it will either condense as creosote or go outside as air pollution. Unburned smoke is a waste because it contains a large part of the total energy in the wood.

The charcoal glows: As the fire progresses and most of the gases and tars have vaporized out of the wood, charcoal remains. Charcoal is almost pure carbon and burns with a red glow and very little flame or smoke. Charcoal is a good fuel that burns easily and cleanly if it is given enough air. Although charcoal combustion produces almost no smoke, the exhaust can have high concentrations of carbon monoxide, so it must be vented completely to outdoors.

In reality, all three phases of wood combustion occur simultaneously because the wood gases can be flaming and the edges of the pieces can be glowing red as charcoal burns, while water in the core of the piece is still evaporating. The challenge in burning wood effectively is to boil off the water content quickly and make sure the smoke burns with bright flames before it leaves the firebox.

A note about the advice offered here

The suggestions offered below are effective for the most common form of wood stove; the front loading, updraft, non-catalytic type. The techniques may or may not be suitable for catalytic stoves, or for cook stoves, furnaces and fireplaces. However, the principles are sound and if you need to use different techniques to get good results in your particular system, that is just part of the variety and charm of wood burning.

Starting a fire

You will need the following materials to build and maintain a good wood fire:

• a newspaper (do not use colored or coated paper);
• a handful of finely split, dry kindling in a variety of sizes; and
• seasoned firewood split into a range of piece sizes.

The first step in building a fire is to find out where the combustion air enters the firebox. For most modern stoves and fireplaces with glass doors, much of the air enters the firebox through a narrow strip above and behind the glass panel. This “air wash” flows down across the glass to the front of the fire because it is cooler, denser and heavier than the combustion gases. Most stoves without a glass air wash system will have an air inlet near the bottom of the firebox, usually just inside the loading door. Some stoves have specialized air inlet systems that can affect lighting procedure.

If you feel cold air when you open the stove loading door and reach inside, your chimney is in cold backdraft. If you go ahead and light the fire without correcting the backdraft, you will fill the house with smoke. You can neutralize the negative pressure that is driving the backdraft by opening the closest door or window to outdoors. Note that the cold backdraft is the result of a system design flaw: either an outside chimney or a chimney that penetrates the building envelope below its highest level. In extreme cases, these flaws can result in hot backdrafts that fill the house with smoke. If your system suffers cold backdrafts, please be aware that it is more than just a nuisance – it can be hazardous. By opening the nearest door or window, you are merely masking the problem and as soon as you close it, the negative pressure will again act on the system, tending to reduce the net chimney draft available to flow the exhaust up and out of the house.

You can build a conventional fire by starting with newspaper and putting kindling on it and then larger pieces, but this method can lead to fires that collapse on themselves and smolder. It also tends to be smoky and fussy because you have to keep adding wood until you have a full fire. Here are three methods you will probably have more success with.

1. Two Parallel Logs. Put down two split logs with a space between them and put some twisted newspaper in the space. Add some fine kindling – one inch across or less – on the newspaper and more kindling of various sizes across the two logs. This method works well because the two logs give some space for the newspaper and kindling to get a good start. Their burning is usually enough to ignite the two larger logs. After the kindling has almost burned out, more wood must be added to make a full fire.

2. Top-down. While this method takes a little getting used to, it is absolutely reliable, and when it is done properly there is almost no smoke right from the start. Just place three or four full-sized split logs on the firebox floor or on the ground. Place several pieces of medium kindling across them and then maybe another layer of smaller pieces at right angles to those. Then put 10 or so pieces of fine kindling on top. Now take four or five full sheets of newspaper and roll each one up corner-to-corner and tie a sloppy knot in it. Knotting the paper helps to keep it from rolling around as it burns. Place the knots on top of the fine kindling. Light the paper and watch as the fire burns down through the light kindling, the heavy kindling and into the bottom logs. Using the top-down method, you can light the paper and watch the fire burn on its own for up to two hours.

3. Using Fire Starters. Many people use fire starters made of sawdust and paraffin wax. You can buy commercial versions or make them yourself. You can even cut up a wax firelog to make your own starters. If the starters are placed among split pieces of dry wood, the fire will start reliably.

The goal when lighting a wood fire is to achieve quick ignition of the load without fussing or waiting for it to catch. After practicing with these procedures a few times, you might be surprised at how quickly you can establish a bright, hot fire.

Rekindling a Fire from Charcoal

For most wood-burning appliances, the live coals that remain after the fire has burned down are found at the back of the firebox furthest from the air supply. This is the time to clear excess ash from the firebox. Before disturbing the remaining charcoal, remove a small amount of ash from the front of the firebox. Now rake the live coals forward to just inside the loading door. If only a small amount of charcoal remains, you will have to start with kindling. If you have a good quantity of glowing charcoal to work with, place at least three, and preferably more than five pieces of firewood on and behind the charcoal. Open the air inlets fully and close the door.

If everything is just right, you should expect instant ignition of the new load. In fact, the bottom pieces should be flaming before you get the door closed. Allow the fire to burn with bright turbulent flames until the wood is charred. This usually takes between 15 and 30 minutes, depending on the size of the pieces and the moisture content of the wood. When the wood is charred, you can reduce the air setting to produce the amount of heat and length of burn you desire. You may want to try reducing the air control setting in two or three stages. The result will be less air pollution because the fire will not have to recover from the single, large reduction in air supply.

The most important rule is NEVER LET THE FIRE SMOLDER. As long as there is solid wood in the firebox, there must be flames or the smoke will escape unburned, both reducing efficiency and increasing pollution. With modern appliances, it is possible to achieve a reliable overnight burn while maintaining flaming combustion and having enough charcoal in the morning to rekindle a new load.

More tips and techniques

Fuel load geometry: Small pieces of firewood arranged loosely in a crisscross pattern burn quickly because the combustion air can reach all the pieces at once. Larger pieces placed compactly burn more slowly because there are fewer spaces where the air can penetrate the load. Never add just one or two pieces of wood to a fire. Three or more pieces are needed to form a sheltered pocket of glowing coals that reflect heat toward each other and sustain the fire.

Fire in cycles: Don’t expect perfectly steady heat output from the fire. Wood fires burn best in cycles. A cycle is the time between the ignition of a load from charcoal and the consumption of the load back to a coal bed. Each cycle should provide between four and eight hours of heating, depending on how much wood was used and how much heat is needed. Plan the firing cycles around your household routine. If someone is home to tend the fire, use a short firing cycle. If you must be away from the house during the day, use the extended firing cycle.

The flash fire is a small amount of wood burned quickly. Use it in spring and fall when you just want to take the chill off the house. The flash fire technique eliminates the smoldering fires that are common in spring and fall. To build a flash fire, rake the charcoal towards the air inlets and place several small pieces on and behind it. The pieces should be stacked loosely in a crisscross arrangement. Open the air inlet to produce a hot, bright fire. The air supply can be reduced slightly as the fire progresses, but never enough to extinguish the flames. When only charcoal remains, the air supply can be reduced further to prevent cooling the coal bed.

The extended fire: To achieve a longer-lasting fire, rake the coals towards the air inlets and use larger pieces of wood placed compactly in the firebox. Placing the pieces close together prevents the heat and flame from penetrating the load and saves the buried pieces for later in the burn cycle. Open the air inlets fully for between 15 to 30 minutes depending on load size and fuel moisture content. When the outer pieces have a thick layer of charcoal, reduce the air control in stages to the desired level. The charcoal layer insulates the rest of the wood and slows down the release of combustible gases. This allows you to turn down the air control and still maintain a clean-burning fire. Use the extended fire technique to achieve an overnight burn or a fire to last the day while you are at work. Do not let the fire smolder.

Removing ashes: When you follow the suggestions for raking of the coal bed, you will find that ashes accumulate at the front of the fireball. These ashes can be removed easily before coal bed raking in preparation for loading. Most modern wood-burning appliances work best when a small amount of ash is removed each morning before the first fire of the day is built.

Look for these signs of good combustion:

• When wood burns it should be flaming until only charcoal remains. If there are no flames, something is wrong
• If there are firebricks in the firebox, they should be tan in color, never black.
• Steel or cast iron parts in the firebox should be light to dark brown, never black and shiny.
• With seasoned wood, correct air settings and proper loading arrangement you should expect instant ignition of a new load of wood — the bottom pieces should be flaming by the time the door is closed.
• If the appliance has a glass door with air wash, it should be clear.
• If the appliance has a glass door without air wash, it will be hazy, but should never be totally black.
• The exhaust coming from the top of the chimney should be clear or white. A plume of blue or gray smoke indicates smoldering, poor combustion, air pollution and probably low system operating temperatures.

B Vent or Natural Vent 

This type of fireplace venting uses economical B-vent pipe for a chimney. Some of its features are:

• Uses room air for combustion and venting terminates above the roofline (like a furnace)
• More decorative, but lower efficiencies.
• Zero clearance to combustibles.
• Relatively easy to install; space-saving depth, but requires finishing such as a mantel and surround.
• Large traditional fireplaces in clean-face or circulating models.
• Ideal for locating anywhere in the home where B-vent can be installed.
• Less Cost than Direct Vent systems

Vent-Free

A vent-free gas fireplace operates without a chimney, flue or vent, so you can install one just about anywhere. Modern vent-free gas fireplaces:

• Inexpensive and have low operating costs
• 99 percent energy efficient provide warmth during power outages
• Design-Certified to the latest national safety standards (ANSI Z21.11.2)
• Do not exceed 40,000 Btu/hr of heat output

Forty-five million homes worldwide and more than eight million American homes enjoy the comfort and convenience of vent-free gas fireplaces. In fact, more Americans are buying vent-free gas fireplaces than any other type of supplemental gas heating product. There are, however, some areas where these units are restricted. Check with your local building departments to see if a vent-free system can be used in your home.

How they work

Vent-free fireplaces operate using natural or propane gas. Most models do not require electricity. Natural or propane gas fuels the flame through a permanent line that is connected to a blue-flame/yellow-flame burner or ceramic plaque burner within the heating appliance.

Inside air quality

The primary gas combustion byproducts that can affect indoor air quality are carbon monoxide, carbon dioxide, nitrogen dioxide, oxygen, and water vapor (humidity). Today’s vent-free fireplaces operate well within national standards and recommendations concerning these five byproducts. The American Gas Association research division (www.aga.org) confirms these low emission levels.

Oxygen Detection Safety-Pilot

Since 1980 vent-free-gas-heating appliances have been equipped with a unique safety pilot system called an “oxygen detection safety pilot,” or ODS. The ODS is the technological innovation that revolutionized the safety of vent-free gas heating appliances by automatically shutting off the gas supply in the rare event that the oxygen level in the room falls to 18 percent, where carbon monoxide production can drastically increase (~20.9 percent is considered a normal oxygen level).

Previously, questions remained about the long-term effect of vent-free gas fireplace emissions on indoor air quality. In 1995 the Vent-Free Gas Products Alliance of the Gas Appliance Manufacturers Association (Vent-free gas product alliance) commissioned a study on indoor air quality as it relates to vent-free gas heating products in the home. The results proved that vent-free gas heating products meet or exceed the most current and applicable nationally recognized standards and guidelines for inside air quality.

Direct Vent

Direct vent fireplace venting uses a coaxial pipe system (small pipe within a large pipe) and draws combustion air from the outside through the outer pipe. Some of its features are:

• An inner pipe vents the exhaust.
• Can either vent out the top or out the back, for installation versatility.
• Can vent horizontally through an outside wall, or vertically through the roof – no chimney required!
• Ideal for adding warmth & efficient heating to a cold room.
• Most are certified as “gas wall furnace” for highest efficiency.
• Zero clearance to combustibles.
• Convenient to install, space-saving depth, but requires finishing such as a mantel and surround.
• Suitable for well-insulated homes or homes with no existing chimney.
• Always have an enclosed front.
• Best choice for newer, more air tight homes.

Please Remember:

The Hearth, Patio & Barbecue Association recommends the installation of a carbon monoxide detector with all gas hearth products.