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Wood Burner's CompanionChimney Savers recommends The Woodburner's Companion by Dirk Thomas to anyone who is considering using wood as a heat source.

With fuel prices still going higher, more people than ever are looking at alternative ways to stay warm. This third edition of Dirk Thomas's popular and authoritative guide adds a section on getting started with wood heat. In addition there is a new "FAQ" section where frequently asked questions are answered.

Thousands have benefited from reading The Woodburner's Companion, first published in 2000, revised in 2004 and now even better in its third edition. You can stay warm without going broke, and as an added benefit, you can weather a mid-winter power outage in style!

2006; Hood, Alan C. & Company, Inc.; 6"x 9";
176 pages Paperback; ISBN: 0-911469-28-1

Q. I've heard that traditional, open-hearth fireplaces are terribly inefficient and are great sources of heat loss in a home. I love the look of them, though. Are they really that inefficient, and how can I prevent the heat loss in the winter?

Unfortunately, fireplaces are inefficient, although they are aesthetically pleasing. Open fireplaces draw combustion air in from the home. That air, along with the majority of the heat it produces, goes up the chimney. Because the air that the fireplace draws up the chimney has already been heated by the primary heat source (wood, oil, gas, etc.) fireplaces usually have a "net heat loss".

There are many options to make your fireplace more efficient. Glass doors stop heat from traveling up the flue, both during use, and when not in use. Traditional metal dampers have a metal on metal seal which allows heat to be lost up the chimney when not in use. To solve this problem a Lock–Top damper which has a gasket seal can be installed on the top of the chimney to limit heat loss (see Caps and Dampers on our Services page). A Rumford–style fireplace can also be built which, briefly put, is a shallower fireplace design that throws more heat into the room.

Many People ask, "If this is so, how come my house was once heated entirely by fireplaces?" Basically, as previously stated, the air being drawn up the fireplace was not already heated by another appliance so there would be some heat gain. Also, (and most notably) the old New Englander's idea of "warm" was a little different than ours, (their homes were not very warm) and they would usually center most activities around the fireplace in the winter.

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Q. How often should I have my chimney cleaned?

This a tougher question than it sounds. The simple answer is: The National Fire Protection Association Standard 211 says, "Chimneys, fireplaces, and vents shall be inspected at least once a year for soundness, freedom from deposits, and correct clearances. Cleaning, maintenance, and repairs shall be done if necessary." This is the national safety standard and is the correct way to approach the problem. It takes into account the fact that even if you don't use your chimney much, animals may build nests in the flue or there may be other types of deterioration that could make the chimney unsafe to use.

The Chimney Safety Institute of America recommends that open masonry fireplaces should be cleaned at 1/8" of sooty buildup, and sooner if there is any glaze present in the system. Factory-built fireplaces should be cleaned when any appreciable buildup occurs. This is considered to be enough fuel buildup to cause a chimney fire capable of damaging the chimney or spreading to the home.

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Q. My local fire department offered to clean my chimney for fraction of what I've ever been charged by a chimney sweep. Should I be concerned about the quality of work they would do? Are they certified? Are they insured?

Chimney Savers is a big fans of all professional and volunteer firefighters. Unfortunately, firefighters are not certified chimney sweeps. While they do a great job of extinguishing fires when they occur, they have not been educated and trained in proper chimney cleaning and inspection techniques and procedures (this, and liability concerns, are reasons why most fire departments have stopped offering this service). When cleaning a chimney there are a large variety of tools needed for a thorough job. For instance, every size liner and kind of creosote requires a different brush. Many times firefighters only use chains which they drop down the chimney to dislodge bird nests and other obstructions, which can leave creosote deposits still in the chimney, and can actually cause damage to some chimney designs. Other times, they may pull a brush through the flue once or twice. These brushes can scratch stainless steel liners. Also, firefighters are not typically insured if their actions cause damage to your home or chimney. In the end, you do get what you pay for in this case.

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Q. We have a pellet stove in the basement, but I would like to add a Vermont Castings wood stove to the living room upstairs. How do I know if the flue is big enough to handle the extra stove?

It is actually against NFPA 211 codes and standards to vent more than one solid fuel burning appliance on the same flue, even if they are not being used simultaneously. An additional flue would need to be added to your home.

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Q. My fireplace stinks, especially in the summer. What can I do?

The smell is due to creosote deposits in the chimney, a natural byproduct of woodburning. The odor is usually worse in the summer when the humidity is high and the air conditioner is turned on. A good cleaning will help but usually won't solve the problem completely. There are commercial chimney deodorants that work well, and many people have good results with baking soda or even kitty litter set in the fireplace. The real problem is the air being drawn down the chimney, a symptom of overall pressure problems in the house. Some make-up air should be introduced somewhere else in the house. A tight sealing, top mounted damper will also reduce this air flow coming down the chimney.

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Q. I don't have a cap on my chimney. Where is all the rain going? Will it flood my basement?

Chimney caps are a tricky subject because each chimney has a different design, different uses, and varying draft conditions. We do not always recommend chimney caps because they can potentially have an adverse effect on draft. In masonry chimneys with terracotta tile liners, rain falling down the chimney is usually absorbed by the masonry before it reaches the basement. This depends on the size of the chimney flue and amount of rainfall. We recommend having your chimney inspected by a certified chimney sweep to weigh the pros and cons of a chimney cap. Many times a chimney cap can protect the masonry on top of your chimney (see Chimney Caps and Dampers on our Services page).

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Q: What is Level 3 creosote?I have an 80 year old home that was a longtime rental house. I have lived here five years and have been using the fireplace for four of those years. I do not know how long it has been since my chimney was swept (potentially decades, if ever). I just had a chimney sweep at my house and he informed me that the creosote in my chimney was quite thick (he used the term "level 3" creosote). He also said that in the smoke chamber, the brick is stepped (instead of smooth) and that there is a lot of dangerous buildup in there. He recommended two applications of an acid cleaning (which he said are not entirely foolproof, and work better above 45°F) and that we use a chemical when we burn our fire to help "chalkify" the creosote buildup. He showed me the buildup inside with a light and everything he said seemed to make sense. Does this sound like it's on the up and up? I can't find any info on this acid cleaning and I would like to know if this sounds like it is the proper course of action in a case like mine.

What you have described sounds pretty typical. In addition to the chemical treatment that you mentioned, professional-grade chemicals, usually in the form of a powder, can be applied by chimney sweeps to help change the nature of the glazed creosote to a form that can be removed by a professional with a brush. Both forms of these products require some heat such as you would find in a small fire in the fireplace.

If the creosote is gummy, about the only way to deal with the creosote is with a chemical treatment or with an acid application. Acid applications are not as commonly used since they are harder to apply and have to be neutralized a few days after application. If the creosote is crusty or fractures when hit (as opposed to gummy) a rotary cleaning can be helpful.

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Q. A tree fell on my roof and damaged part of the chimney. Do I need to replace the entire chimney?

In this case, you would want to ask a certified chimney sweep for at least a Level 2 chimney inspection, and if required, a Level 3 chimney inspection. It is possible that the entire chimney will not have to be taken down.

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Q. The mortar where the stove pipe enters the chimney falls out every year. Is there a flexible or more durable solution?

This problem is very common in chimneys with stainless steel liners. The liner expands when heated and it contracts as it is cooled, thus damaging the mortar around the thimble. Unfortunately there is no UL listed product that is flexible enough to withstand this expanding and contracting. The best solution to this problem is to install what is known as a trim collar on the stove pipe. A trim collar is best described as a round metal plate that slips over the stove pipe; it sits fairly flush against the wall and covers any missing mortar. It is also important to fill in any gaps around the thimble with high heat insulation. Trim collars can be found at most hardware stores that carry stove pipe products.

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Q. I was in my attic the other day and noticed creosote dripping down the brick of my chimney. Why is this happening and how can I clean it?

With chimneys that vent oil or gas appliances, you would think that no creosote should be present. However, home owners often have this problem. To answer this question, it is best to explain it in two parts: 1) Why is there creosote in the chimney in the first place? 2) Why is it now staining the bricks?

To answer the first part of the question, it is important to note that in older homes, wood and coal were once the main heat source. Unlined chimneys were used to vent these appliances. The residue (i.e., creosote and soot) from these appliances remained in the chimney when homeowners switched over to oil and gas heating systems (vented in the same chimney).

This brings us to the second part of the question. To put it simply, this residue is now leaching through the bricks because of moisture. When the gases being vented hit the part of the chimney exposed to cold outside temperatures (e.g., a cold attic or the exposed top of the chimney), they condense, turning gas into moisture. This problem is becoming more common as more efficient appliances are being installed. Generally, the more efficient the appliance the lower its stack temperature (stack temperature is the temperature of the gases when they exit the appliance and enter the chimney). A low stack temperature causes the gases to move slower through the chimney allowing them to condense more easily.

The solution to this problem is to install a stainless steel chimney liner, which creates a barrier between the gases and the bricks. This liner will be properly sized for the appliance and will retain heat, improving draft and eliminating almost all condensation. Moisture can also be coming from the top of the chimney due to a variety of problems (e.g., cracked or missing mortar, improper flashing, or porous bricks).

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Q. What is the average life expectancy of a properly constructed chimney?

3. This is a difficult question to answer because there are so many variables that can affect the life expectancy of a masonry chimney. Many chimneys built in the 1700-1800s are still standing today, although most are in a deteriorated condition. Back then chimneys were built in the interior of the house (i.e., through the middle of the house) and vented either a fireplace or coal/wood stoves. In the winter they were continuously run. This extensive use actually helped to maintain the integrity of the masonry above the roof by keeping the chimney warm and dry. In present times, with increased prevalence of oil and gas boilers, this continual use of the chimney is no longer a common practice. This allows moisture in the bricks on top of the chimney to freeze and thaw throughout the winter, damaging the bricks and mortar and thus shortening the life of the chimney. Oil and gas appliances also vent corrosive gases that frequently condense inside the chimney, adding more moisture to the problem and eating away at the chimney from the inside out. Also, many times we see chimneys that are completely shaded by close trees or that have ivy growing on them, making it difficult for the chimneys to dry out after it rains or snows.

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Q. Do pellet stoves generate less creosote than traditional wood stoves?

There is a common misconception that pellet stoves don't actually create any products of combustion (e.g., creosote, soot, or ash), when in fact they do. Pellet stoves actually do produce creosote and a significant amount of ash. This ash is very fine and requires a special HEPA vacuum filter to dispose of the dust.

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Q. I'm planning a new house. Is it better to locate my chimney in the center of the house or on an end wall? Why?

The northeast is a harsh environment for chimneys! Chimneys endure a combination of freezing and thawing, rain, snow, and in the case of oil/gas appliances, corrosive gases. Although there are many options to consider (e.g., house layout, surrounding trees or buildings, etc.) the best positioning for a chimney is usually the middle of the house. Exposure to the elements is never favorable for a chimney. Thus, for maximum longevity it is best to have as much masonry as possible inside the house. Having a center chimney also allows you to place a heating appliance in the center of the home, which can give you a more even distribution of heat. Having a chimney built on the outside of the house can give you a variety of problems. First, you can have draft problems. Because the masonry of a chimney can become extremely cold in the winter it is hard with wood burning appliances to get a good draft going up the chimney. This can cause an increase in creosote build-up, which can be extremely dangerous (see our article on creosote). In addition, an outside chimney is sure to create added condensation of flue gasses, which can damage terracotta tile lined chimneys. Finally, with an outside chimney there is the potential for heat loss problems. Heat can be lost as it is transferred through the masonry to the outside environment.

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Q. I'm installing a new wood-burning insert and liner; do I really need to insulate the liner?

Yes. In the past some manufacturers' instructions for installing their liner systems were vague about whether or not to insulate their liners. But now the instruction manuals are usually worded to where there is no doubt about the need to insulate.

The insulation of a flexible or rigid liner is a smart choice and increases the safety within the flue area. Keep in mind that most masonry chimneys do not meet proper clearances to combustibles.

Flue gases tend to cool down more as they rise in an un-insulated liner with the end result being increased creosote buildup and reduced draft therefore reducing the efficiency of a modern stove. On the other hand, the effects of an insulated liner would be higher flue temperatures throughout the system, less creosote buildup and increased efficiency. The emissions generated from the appliance would exit the chimney faster with less residence time.

Most wood-burning appliance manufacturers either require, or highly recommend, the use of stainless liners with their appliances. Currently the most widely-used reburn technology splits the incoming air into three directions as it enters the combustion chamber: the base of the fire, the airwash (which keeps the viewing glass clean) and below a baffle through a series of tubes where oxygen meets unburned wood gases and reignites, lowering the overall emissions and increasing the stove's efficiency. An insulated liner is a must for optimal performance on any high-efficiency appliance.

We probably all have our favorite liner companies that we deal with regularly. Before the busy season, it would be a good idea to check with your liner and stove manufacturers to make sure of their requirements.

Written by Dennis Dobbs, NCSG - Technical Advisory Chair (Sweeping Magazine, September 2011).

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Q. How long does a chimney sweep/ chimney cleaning take?

A chimney cleaning can last anywhere from a 20 minutes to over 2 hours depending on the chimney. Every chimney/house is different and presents its own challenges and techniques.

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Q. Should I do anything to prep for my chimney sweep?

Yes. It is always a big help to clear the area around the appliance or fireplace that we will be servicing. Moving any decorative items from the mantel is also a good idea. In most cases we also have to access the clean out door, usually found in the basement or crawl space, which is often a favorite storage spot.

During the heating season your stove and stove pipe must be cool enough for our technicians to handle. If you let the fire die out the night before we arrive it should be cool enough to sweep. If you have a soapstone stove or masonry heater, it could take as much as two days to cool down.

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Q. Is it ok to paint over brick?

No. Brick, concrete, and mortar are earthen materials that need to breathe. Moisture gets into these materials from the outside (think rain and snow), but this moisture typically evaporates when the sun comes out. Moisture is also absorbed from the ambient air (think humid air) and from moisure inside of a house that lacks proper ventilation. All of this moisture needs to be able to get out, or else mortar will deteriorate more quickly, and concrete blocks will soften and crumble. Rather than painting, we recommend sealing the surfaces with a waterproofing product that still allows moisture to escape. Please see our Masonry Waterproofing page for more information.

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Q. What are the parts of a fireplace?


Rain Cap Arrestor: The chimney cap is the metal mesh screen that has a lid on top of your chimney. The cap is sometimes referred to as a flue cap, chimney cap, or cap for short. The rain cap arrestor is designed to keep critters and rain from entering your chimney and sparks from exiting out onto your roof or nearby combustibles. For heavy wood-burners, the pros and cons of a cap should be weighed.

Crown: The crown, also known as the “wash,” is the masonry top of your chimney that covers the bricks and encases the flue. A crown prevents any water from entering in between the brick and flue liners.

Flue Liners: In traditional masonry construction, flue liners are 2-ft terracotta tiles that are stacked one on top of the other, creating the flue that forms a passageway for gases and smoke to travel up the chimney. Flue tiles come in different shapes (oval, round, square and rectangle) and sizes (8"x13,"8"x17", 13"x13", 13"x17", and many more). The tiles are sealed together using refractory mortar, which is able to withstand the extremely high heat.

The Flue: The flue is constructed of flue tiles and is where the smoke travels up to exit your chimney.

Smoke Chamber: The smoke chamber is the open area that extends from the top of the smoke shelf to the base of the flue. There should be a smooth transition here for the smoke to travel into the flue.

Smoke Shelf: The smoke shelf is located behind the damper and is used to prevent downdrafts and debris from falling into your firebox.

Damper: The damper is a valve into the fireplace that is movable, usually controlled by a lever. When open, the damper allows the smoke to enter into the smoke chamber. When closed, the damper prevents heat from escaping the house and up the chimney. It also stops animals, birds, soot and debris from falling into the firebox.

Throat: The throat is an opening above the fireplace firebox through which flue gases pass into the smoke chamber. The fireplace damper frame assembly is usually located at the throat of the fireplace.

Firebox: The firebox is the chamber where the fire is contained. It is usually constructed of refractory firebricks.

Lintel: The lintel is an iron bar that holds up the top of your firebox opening.

Hearth: The hearth is the area in front of your fireplace that is made from masonry materials (brick, tile, sandstone, etc.). It is designed to prevent embers from igniting the flooring directly in front of the fireplace. In most cases the hearth should extend out at least 16 inches.

Ash Dump Door: The ash dump door is a small door located on the floor of your fireplace that is used to dump ash remaining after a fire in your fireplace. Not all chimneys are built with one.

Ash Pit: The ash pit is the area where the ash is deposited from the ash dump door.

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