Your Questions, Our Answers
Questions and Answers about woodheat
We have enjoyed receiving questions from our visitors because they tell us what's on peoples' minds and suggest to us things we should put on the site to make it more useful. There is a big resource of questions and answers just a click away. We even separated the Q&A content into the categories in the column to the right.
Q&A About Wood Burning and the Environment
When trees are taken, what is lost from the forest?
Hi, Nice site. I recently bought a house whose source of heat is a wood burning stove. I've really gotten to enjoy using it and I was very interested in your environmental reasoning for using wood vs. fossil fuels.
I looked all over your site and read the All About Smoke section, but have not been able to find an answer to this question: What is the chemical constituency of wood? I understand that there is carbon, oxygen and hydrogen, but what I am looking for is all the materials that make up wood so I can differentiate which substances are burned off (smoke) and which ones stay in the fireplace (ash). I am very curious for reasons of sustainability. When wood is taken from a forest, a certain amount of minerals are taken with it. As a tree grows it stores carbon from the atmosphere, but also "pulls" minerals/substances/chemicals from the soil that also are stored in the wood. When one takes a tree away from its native habitat, one is also taking these substances away. The carbon will get cycled back into the atmosphere, but the other substances have been removed permanently. I would like to know what all those substances are, both the ones in the ash, and the ones that may also go up the chimney with the smoke.
Thanks, Mike
Hi Mike,
Yes, you are quite right that when trees are taken for fuelwood something is lost from the site. You are also right that the main loss is in the form of minerals. However, keep in mind that in the entire life cycle of the tree, the part taken is only certain fraction of the total contribution to the site of that tree. Each year deciduous trees deposit a fair mass of leaves on the forest floor and coniferous trees drop leaves on a continuous or multi-year cycle. Over a 50 year period that is a big contribution to the mineral and biomass stock of the soils. When it is harvested, we take only the bulky solid wood, not the entire tree. Also, in most of North America about half (it is hard to estimate) of the firewood produced is a byproduct of other forestry operations that produce saw logs or pulp.
As we point out up front, whatever energy source you use will have impacts. I can only say that I've seen wood lots that have been harvested selectively for firewood for generations and they look terrific. My assessment is that a healthy, well managed forest can tolerate a moderate loss of biomass each year without any decline in viability.
To get a more scientific answer you would have to ask a forest ecologist, of which there are very few.
John
Wood burning is bad for your health?
I went to one of the links and there was a whole nine pages of why woodstoves are bad for you and the environment. In particular, it talked about the toxins and carcinogens that wood burning lets off. It seems we have to decide to either burn a hole in our lungs or burn a hole in our pockets.???
Tracy in Toronto
Hi Tracy,
We link to Burning Issues as much for comic relief as for factual commentary. Pick any single environmental issue and you'll find at least one organization run by fanatics. Burning Issues is run by folks who are, for whatever reason, fanatical about wood smoke. From our point of view, it is better to have opponents who are so intemperate, so radical, so uncompromising as to be dismissed by reasonable people as fringe loonies. That's why we are happy to link to Burning Issues.
Please don't misunderstand me, we don't consider wood smoke good to breathe. Clearly, it is not healthy for you. But neither is diesel truck and bus exhaust or car exhaust or many other pollutants. This is from the Union of Concerned Scientists:
"The average truck on the road today spews 22 grams of smog-forming pollution and nearly one gram of soot every mile." See:
http://www.ucsusa.org/transportation/brf_bigdiesel.html
That is about 60 g/h of particulate matter at highway speed. My EPA certified wood stove emits an average of 3 g/h of particulate matter per hour of operation. So what should have priority, my home heating or a truck taking computer games to Wal-Mart?
I don't like to justify wood burning emissions just by saying the other guy is worse, but we must put all pollution into proper perspective and reduce it all. At woodheat.org, we don't suggest that everyone in Toronto should start heating with wood, quite the opposite. We think wood is appropriate as a regionally specific energy resource.
So, I don't think the options are "to either burn a whole in our lungs or burn a whole in our pockets". Responsible people can reduce their personal pollution and also reduce cost by choosing good equipment and practicing energy conservation. The fact is we'll all be practicing energy conservation fairly soon whether we like it or not. See:
Finally, in light of Burning Issues warnings of immanent disease and death from wood smoke, consider this: The human species lived with its collective head in a cloud of wood smoke for its entire million year history on earth, until the last 150 years. If the periodic exposure to the smell of wood smoke were anything like as toxic and dangerous as the fanatics would like you to believe, we never would have got this far.
John
Misleading Statement?
In searching for material on wood burning stoves, I came across your web site. I find that it has a good deal of useful information, however, there is a very misleading statement that is made on the homepage. It is given below.
"But when it is used effectively, wood is a fine fuel compared to the fossil fuels like oil, gas and coal, whose consumption leads to global warming."
I will not get into the debate of does carbon dioxide cause global warming, because I think the answer is not really known. However, to make the assertion that burning wood is better than burning oil, gas, or coal because of global warming is absurd. Wood like these other fuels is a hydro-carbon. If it is burned completely and perfectly, its byproducts, water and carbon dioxide, are the same as what is produced from burning coal, oil, or gas. The statement on your home page should be modified to reflect the facts. It will also lend credibility to your site.
John
Hi John,
We find your message very interesting, not least because we gather you are with Sandia Labs. You are not just a curious nonspecialist who might be unfamiliar with the carbon cycle as it relates to atmospheric CO2 and biomass growth, decay and combustion. See:
http://www.woodheat.org/carbon.htm
http://www.woodheat.org/forest.htm
(or simply type 'carbon cycle' into any search engine)
We don't spend time debating the greenhouse gas/global warming/climate change issue because more than sufficient information is available now to take action. We note that those who persist in denying any connection are usually paid to do so, directly or indirectly, and therefore lack credibility.
We stand by the quoted statement on our site – it is not misleading. We think it is misleading to suggest that, in the area of energy use and the environment, business as usual is the desirable strategy. You are just going to have to live with the fact that we disagree with you.
Regards,
John
A challenge to wood as a renewable resource
While I agree that wood heat alternatives might be better in the short term than fossil fuel dependency, the world is also in deforestation crises, and by encouraging wood use, you are fostering this depletion – another imbalance to our ecology. We need to find an alternative energy source that truly is "alternative" and does not rely on "endangered" resources.
Sincerely, Roberta
Roberta,
Only a fool would suggest that wood is the right fuel for all regions and all situations (as the fossil fuel promoters do for oil and gas). You can dismiss us as irresponsible if you wish, but I think we promote the moderate, sustainable use of wood as a fuel. I am guessing that you don't fully understand the concept of renewability (see this page).
It is naive to think that 'science' will surprise us with a new energy source that will solve all our problems. The solution lies in using a lot less energy of all types and using more regionally specific and appropriate fuels. But then, I suspect you have your mind made up.
John
Roberta responds:
John,
Thank you for responding so promptly and so intelligently! Your "suspicion" is correct in that I haven't fully explored your concept of renewable as far as wood burning is concerned – and yes, I agree, it's naive for us to think that "science" will save us and our Mother Earth. I'm just recently reading Thom Hartmann's book, "The Last Days of Ancient Sun" and am blown away by how serious our situation is – and am deeply concerned as to how we can "wake people up" to become more responsible and change the "burn and conquer" mentality and history we've inherited. When I was "surfing the net" and marking sites for future reading, yours just happened to have an email response for me to complain to. No, I haven't gotten my mind made up – I'm just concerned and exploring.
Again, thanks for your response – and good luck!
Roberta
Q&A About Maintenance
Do chimney powders work? Are there any dangers?
How effective are creosote powder cleaners? The brand I have is [****], and the active ingredient is cupric chloride. Are there any dangers to the use of this material, and are the ashes of concern as far as toxicity is concerned?
Thanks for your help, James
Hi James,
Here is an excerpt from the Wood Energy Technical Training reference manual, part of the Canadian training and certification system for wood heat technicians and inspectors:
" Chloride-based powders, containing copper, zinc, or other metals, are the oldest form of chimney chemical. The active ingredients in these powders are the heavy metals and chlorides which have the corrosive qualities of salt. Chloride-based powders are effective only at high temperatures, so they are sprinkled on an intense fire. Tests have shown that this form of anti-creosote powder is not particularly effective and the chloride-based powders attack steel and cast iron. Therefore, chloride-based powders are not recommended."
I would also point out it has been found more recently that the combustion of organic materials (like wood) in the presence of chlorines/chlorides, such as salt, bleach, plastics and so on, promotes the formation of the toxic pollutants dioxin and furan.
The best way to remove chimney deposits is through brushing. If deposits form quickly or are difficult to remove, the problem is fuel quality and firing technique.
If you really must use a chemical treatment, look for manganese based liquids. They actually work somewhat if used correctly.
John
What to do about rust on a stove?
Hello, I have a question. We recently had installed a used wood burning stove that was in perfect condition when we got it this past spring, but with all the humidity we have experienced this summer, it has started to show some rust. What is the best way to deal with the rust. Is there something we should do to protect it? Perhaps some kind of oil? Moving it and painting it is not an option.
Thank you, Barbara
Barbara,
I have painted many stoves right where they are with no problems.
Stove paint (at least the good stuff like Stove Bright) dries almost instantly, and the cans have good nozzles that enable you to do a great job without a lot of over-spray. Use a cardboard shield to do edges, and open the windows and you'll have your problem solved in 10 minutes. Of course you'll have to steel wool off the rust first.
Cal
How do I maintain my axe?
I am looking for good, specific information on maintaining axes. How to sharpen properly, is it good practice to put axes in water for a while to keep the handle from drying out and preventing the the axe head from loosening, etc.
Hi,
I don't think there is much to maintaining an axe, at least I've never had any problem. Here's what I do: I use a bench grinder to do general shaping and nick removal, then I use a standard file to sharpen or touch it up.
I've never found soaking in water to be all that useful. I think it is better to do a good installation of a new handle using wood wedges and glue. My experience is that if the handle is put on properly once, it won't come loose.
John
Can I sweep my own chimney?
Thank you very much for the information supplied in your site. I was afraid to use my huge silver maple as firewood and now you make it clear that it will work fine if used properly. I have a question though - I am an avid do-it your-selfer and would like to do my own chimney sweeping. I have very easy access to my chimney and the chimney is a straight shot down only 13 feet. Is there any way I can be allowed to do this myself with limited education related to my specific situation? Where can I find the proper equipment and instruction?
Best regards, Paul
Paul,
Certainly you can clean your own chimney. If access is as easy as you say, I could even do it!
Sweeping equipment is available at any good fireplace specialty store, and some hardware and big box building supply stores. The brush needs to fit the chimney properly, which is to say snug, but not too tight. If your chimney is masonry, you may have to trim the bristles of a wire or plastic brush to fit its shape. Metal chimneys and liners are easy to get plastic brushes for since they are in three standard sizes: 6, 7, and 8" round. Then all you need is some rods for the brush and a decent vacuum to control the dust.
Happy sweeping, Cal
Chains in chimneys and full liners for inserts
Hi, I have been heating my house with a woodstove for 25 years. I use a freestanding stove in front of a fireplace. A 5" flue exits the rear of the stove and passes through a plate in the fireplace opening. I burn a hot fire and clean the rectangular clay chimney yearly. Over the years a slick, smooth hard coating of creosote has developed on the chimney walls which a normal cleaning does not remove. After some research I learned that a rotary chain device would remove the material. Naturally, my first question was, "What degree of damage does the chain do to the chimney?" The answer was, probably some. The suggested remedy for the damage was a 5" stainless liner from the stove to the top of the chimney. Question #1 Is the rotary chain method the best and/or only solution for removing the hard slick creosote? Question #2 If an insulated stainless flue is installed from the stove to the top of the chimney is it necessary or only desirable to remove the coating first? Question #3 What effect on stove efficiency will the full length 5" flu have as opposed to the current setup where the flue exits the stove and only passes through the plate in front of the fireplace? Thanks Walt
Hi Walt:
Question #1 Is the rotary chain method the best and/or only solution for removing the hard slick creosote?
There are chemicals available but they take patience since they only soften the surface, so it might take several applications with brushings between to remove the deposit. Chain is not the only rotary option, in fact I think chain would do too much damage. There is a creosote removal tool that uses three loops of fairly thin stainless steel cable, which is less brutal on the chimney. The looped cable tool, sometimes called a whip, is used by a lot of chimney sweeps.
Question #2 If an insulated stainless flue is installed from the stove to the top of the chimney is it necessary or only desirable to remove the coating first?
Yes, it is strongly recommended because if the glaze creosote caught fire outside the new liner, it would produce a nasty fire in a place that is hard to get at. If you put in the effort to clean it first, you'll feel a lot better about running the stove afterwards. I like insulated liners but I wouldn't insulate the liner from the stove to the original fireplace throat area because this can lead to overheating and damage to the liner. Only insulate the liner once it gets up into the chimney.
Question #3 What effect on stove efficiency will the full length 5" flu have as opposed to the current setup where the flue exits the stove and only passes through the plate in front of the fireplace?
I expect you will find your stove transformed, at least that's what customers of mine found (back when I had a retail store) when we relined the chimney of an existing insert. Your fires will light easier, built to a hot fire faster and, if the liner is installed correctly and the stove run well, you'll only ever have to remove flake and powder from the flue, not sticky creosote.
By the way, a full liner to the top of the chimney is mandatory in Canada for inserts and hearthmount stoves for just the reasons you found. I think the US homeowner gets a raw deal from installers who don't know enough to run full liners and from dealers who don't point out the problems and risks. Just because a 'direct connect' is cheap doesn't make it any good. That's why we pushed for a regulation on full liners and got it ten years ago.
Good luck with it.
John
What should I do with my ashes?
I am a new home owner with a woodstove insert that was already in the house. We are enjoying the recent use of it and are looking forward to heating our house with it while sharing the duties with the high efficiency gas furnace we have.
The question I had was regarding the ash leftover from periodic burning in the woodstove. What do we do with it? I have been putting some in our composter but could see it filling up over the winter with lack of composting activity. Do I put some in the garden? What are my options in an urban area of this size?
Thank you very much for your time and I really appreciate the information of the website, it was all very helpful. I look forward to using many of the tips and techniques listed here and am looking forward to a season of wood heating.
Thank you for your time. Peter
Hi Peter,
Ash can be good for soils because it reduces acidity and adds some minerals. I've also heard people say that ash can be useful as an anti bug dusting for plants, but don't know the details. There is some concern about putting a lot of ash year after year on a vegetable garden because of the possible build up of heavy metals that occur naturally in the wood but which concentrate in ash and are absorbed by the veggies.
As to what to do with the ash, here are some ideas:
- use sparingly on a vegetable garden to reduce soil acidity
- use as much as is appropriate on flower gardens
- keep some around to use on the driveway to give traction on ice
- dig a small pit in the corner of your lot and bury the ash
- take the ash to the local waste disposal site (dump)
- ask your municipal government if you can put it out with the garbage
I wouldn't put ash in a compost bin or pile unless you have checked the ph of the material first.
John
Is stove black the right finish for my stove?
Great site! Thanks for all the terrific information.
I am a new wood stove user. I am in search of information for maintaining my stove. I know I need to use well seasoned hardwood and keep my chimney clean, but what else is needed to keep a stove in good working order?
What is stove blackening? What does it do? Is it the same as stove polish? Are there other products that need to be applied to the outside of the stove or chimney? Any help you can provide or point me to other sites will be appreciated.
Thanks, Debra
Hi Debra,
Stove black is the same thing as stove polish, which is a waxy paste used to make stoves black and shiny. It is now used only for antiques for a couple of reasons. First, it's not water proof, so if water lands on the stove it will rust.
Second, stove polish was used in the old days when stoves were cared for lavishly and gleamed from being polished on a weekly basis. We don't do that much any more.
There are some terrific high temperature specialty wood stove paints in a range of colors that have become the standard way to spruce up wood stoves. The paint lasts up to five years, depending on how the stove is used.
Other maintenance tasks include replacement of door and door glass gaskets and making sure that internal baffles and bricks are in place and still sound. Not knowing what kind of stove you use makes it hard to give clear advice on maintenance. One of the best ways to get familiar with these issues is to hire an experienced chimney sweep to do a thorough servicing of the stove. After that, you can decide which of the tasks you can do on your own from then on.
John
How to spruce up a cast iron stove
I have a 10 year old black cast iron wood-burning stove that is still in good working condition, but needs to be cleaned up a bit on the outside. I've been told that a thin application of mineral oil will make it look new and cause a minimal amount of smoke to be emitted on the first use afterward. Do you have any suggestions for any other cleaning products or methods?
Debbie
Debbie,
Before the days of reliable heat-proof paint people used stove black, or stove polish, which was waxy. Applied and then polished, it produced a very nice finish with slightly silvery or metallic highlights on the castings. But after firing, stove black was not water or corrosion resistant, so the stove would rust at the slightest provocation. Maintaining a stove with stove black was just another routine job for overworked rural women. All this went out of fashion many years ago when good, reliable, corrosion resistant heat-proof paints came along.
The best way to do a full paint job is to take the stove out to the garaage where the overspray and fumes are less of a problem. You can do minor touch ups with the stove in place as long as you use a sheet of cardboard behind the stove to catch overspray.
It will stink the first few times you run it so you'll have to open windows. But the finish will last for several years instead of several weeks as with stove black. You can paint the stove flat black like it was, then stove black and polish it if you really want it to look nice. You can get good stove paint at a fireplace or stove store.
I don't think mineral oil would do much or for very long on a stove because the oil will vaporize pretty quick.
Regards,
John
Debbie responds:
Thank you for your response. I spent more time on the Internet looking for cleaning solutions and found reference to both the stove polish that you described and also the heat-proof paint. It was nice to get some educated input prior to any purchases. Thank you!
Regards, Debbie
Q&A About Tips and Techniques
How to "bank" a wood stove?
How do you "bank" a woodburning stove so it will burn throughout the night?
Sara
Hi Sara,
Banking is an old term that dates back to the days of cast iron stoves with leaky joints and no gaskets on the doors. With little control of the rate of combustion, users had to use devices like flue pipe key dampers (which we shouldn't need to use any more) and place large unsplit, and sometimes unseasoned 'blocks' of wood at the back of the firebox in an effort to extend the burn. These were the days when a wood stove would deliver a net overall efficiency in the 25 - 35 % range and banking was necessary to get them to burn more than a few hours without reloading.
Things have changed. New stove models are roughly 70% efficient, have glass doors that will stay clear for a week or more of full time use if the stove is operated right, and these stoves will easily burn over night while still producing a nice flaming fire. Smoldering is no longer necessary to get an over night burn.
It is still useful to load a stove carefully to get a long burn. It helps to place larger pieces more compactly in the firebox, because they break down more slowly that way.
If you can't get an overnight burn with a modern wood stove, then it is probably too small or something is wrong with it. If you are trying to use an old stove, I would strongly advise you to save up your money and plan to replace it as soon as possible. Using old stoves is frustrating and wastes a lot of wood.
John
Fireplace doors open or closed?
I have looked over your site and didn't find an exact answer for my question. Should you close the glass door of your fireplace when burning a fire or should you leave them open? I have heard arguments for both sides. I heard that leaving them open you draw out more heated air then you gain from a fire and on the other side of the coin when leaving them shut you seem to not get very much heat from a fire. Please help. I have wondered about this for years.
Ron
Hi Ron,
Yes, that argument has gone on for a long time but the reality is it doesn't much matter whether the doors of a conventional fireplace are open or closed, it will work poorly either way. With doors open you get direct radiation from the fire, but the warm air is sucked up the flue and the fireplace is vulnerable to smoke spillage into the room.
With doors closed, the normal tempered glass blocks almost all the direct radiation, but the doors do reduce air consumption and susceptibility to smoke spillage. I would recommend operation with doors closed, but then you risk shattering the tempered glass.
There is no good solution. We recommend putting an EPA certified fireplace insert into the fireplace with a full stainless steel liner to the top of the chimney to make the fireplace efficient, safe and more pleasant to use.
John
A little nervous about wood heating
I have just moved into a house in a rural area where the power goes out frequently. The house has a wood stove. I am concerned about the safety aspects of using it as the only heat source during power outages. Can I let it burn constantly for days? Is it safe to leave it burning while I am sleeping or out of the house? Does it give off carbon monoxide? How do I know if it's time to have the chimney cleaned? I have been checking it with a mirror but don't know what the indications of creosote build up are. Should I burn the wood slowly or fast? Should I shut the damper and vents before I go to sleep? Any info you could send me would be greatly appreciated. Thank you.
Hi,
The first thing you need to do is find a qualified person, like an experienced chimney sweep or stove installer, to come and clean the system thoroughly and inspect it. All you need to know is if the unit and chimney are installed exactly according to safety codes. If they are and the stove and chimney are in good condition, then:
- you can use it as your only heat source
- you can burn hot fires constantly if you want without fear of fire, although continuous high firing can damage the stove
- you can burn it over night and while you are away as long as you run it carefully and make sure the door is securely latched
Your sweep can advise about creosote build up once he sees the system. You can find good firing instructions in our Tips section. In terms of building an extended fire, the idea is to maintain flaming combustion. Do that and you can't go wrong.
John
A little confusion and bad advice about flue dampers
Hi.
I found woodheat.org to be quite full of information. My first wood stove has been installed, and I'm not sure how to use the flue damper and air inlet supply on the stove. What is the purpose of the damper and how should it be adjusted during various burn times? How does the stove's fresh air supply and the damper work in conjunction? For instance, if one is wide open should the other be, and vice versa?
Look forward to your response,
Rich
Rich,
I don't know what stove this is, but operating instructions are usually provided by manufacturers and those should be your main resource. In fact, we don't recommend the use of flue dampers, unless what you have is a bypass damper that is part of the stove. But I don't have enough information to help you much.
John
Rich replies:
Thanks for the response. The stove is a Waterford Ashling Woodburning stove. It is set up with a rear horizontal flue. Approximately 14" from the flue spigot flange is the damper. The store I purchased the stove from included the damper. I just assumed this was the correct procedure. As a matter of fact there is no mention in the owner's manual about using a flue damper, only the primary air settings. This seems to support the statement -"we don't recommend the use of flue dampers". Why should I not be using the flue damper? A friend has beaten into my head that the flue is critical in controlling the amount of heat the stove puts out. He said if there is no damper or the damper is opened all the way, the heat just goes up the chimney. The Ashling has a 'top air duct assembly' and a 'top plate' with (for lack of proper verbiage) baffles. My interpretation of this design is that these two items are to collect and radiate the heat built up in the firebox. Yes, No? I am very surprised that a wood stove store would promote the use of key dampers.
Rich
Rich,
A flue pipe key damper should only be used when you can't control the rate of combustion from the front end using the stove's combustion air control. Key dampers are associated with various forms of smoke spillage into rooms, the simplest being when someone opens the loading door without first opening the key damper. But key dampers are also implicated in cases in which, as the flue temperature falls towards the end of a burn cycle, draft collapses and the restriction offered by the key damper can produce a condition in which the easiest path for exhaust is out through the combustion air control or any other leak or opening in the appliance. This is not very common but it does happen with cooking ranges or sidedraft wood stoves with rear exit flue collars, for example. The rear exit on your stove makes this a possibility.
Key dampers are only acceptable for non airtight appliances, such as old cast iron "non-airtight" box stoves. Flue pipe key dampers restrict flow even when open, provide a place for creosote to build up and make the flue pipe harder to clean. Your friend has expressed the conventional knowledge related to key dampers; that they prevent heat from being lost up the chimney. But what counts is the rate of flow of gases through the system. The faster the flow, the lower the heat transfer efficiency. If you can slow down the flow to give time for heat transfer, it doesn't matter how you do it. It is incorrect to think that only a damper downstream of the combustion chamber can 'keep the heat in'. By controlling the amount of air allowed into the fire with the air control, you have only one control to manage and you don't suffer any of the downsides to key dampers.
I'm not familiar with the Ashling so I can't comment on the fancy terms used to describe its innards. It could be that the first is just to keep the door glass clear and the second is to improve combustion and heat transfer. Most modern stoves have these components, but some manufacturers like to dress them up with fancy terms.
John
Rich replies:
Thanks for your help. It's interesting how some stores are in business only for the buck. The store I purchased the stove from never asked about the original flue, nor fireplace. They simply stated 'buy this, that and that, and we'll install it'. After a bit of research I opted not to listen to them and had a chimney sweep install a double wall solid pack chimney. It cost more monetarily, but provides greater safety and peace of mind. I appreciate your response to my questions, and will control the burn rate using the stoves intake only and leave the damper wide open.
Thanks, Rich
A backpuffing woodstove
I have a fisher baby bear woodstove. It has one draft knob in the center of the stove. I have been heating with this stove for five winters. This year I have noticed considerably more backpuffing of smoke around the air draft knob, especially when I am first building a fire. Generally once I get the stove to settle down, I don't have any more trouble. Do you have any advice on how to remedy this problem. Any help would be greatly appreciated. Thank You, Sam
Sam,
The backpuffing you describe is usually caused by ignition of a build up of combustible gas in the firebox. It means there is too much smoke and too little combustion air. When transient conditions produce rapid ignition of the smoke, the resulting increase in firebox pressure produces the puff. Low draft and a smoldering fire is often the culprit. You might want to have the chimney and fluepipe checked to make sure there is no obstruction limiting your draft. If the chimney is clean, you could probably solve the problem by using more paper, more pieces of smaller drier kindling and built up to heavier pieces more slowly. The idea in getting a fire going well is for combustion to be bright and turbulent right from the time you light the paper. Let the stove get good and hot and wait until the wood is thoroughly charred before turning the stove down at all. It is almost impossible to have a backpuff if combustion is bright and hot. By the way, one good way to avoid smoldering at start up is to use the topdown fire building technique, a description of which you will find in our Tips section.
John
How to start a fireplace
I have the old fashioned fireplace that is not a gas fireplace. I am having trouble lighting it and keep it lit. What is the best way to start a fire that will last for a long while. Thanks, Brendie
Hi Brendie,
The key to starting a fire is to make sure the wood is dry enough and is split up small enough to ignite. Problems starting and maintaining fires usually have to do with dryness and piece size. Small pieces light easier than big pieces so use about 10 pieces of finely split dry kindling. Use several sheets of newspaper to ignite the kindling. The successful ignition of a wood fire starts with the newspaper and progresses steadily to larger and larger pieces until the full sized logs ignite. You'll find more information in our section on tips and techniques.
Beyond that, you'll need to practice. I'm still practicing and I've been heating with wood for 35 years!
John
If it's gross and bothersome, something is seriously wrong!
We heat with wood in my house and I find it warm yet it's smell is gross and bothersome.
You are in serious need of professional help. There should never be the smell of smoke inside a house. Good systems NEVER spill smoke inside. Contact a chimney sweep or experienced retailer to get the system inspected and corrected. Your health and that of your family are at stake.
John
Q&A About Chimneys
Wood Stoves in A-Frame Buildings
Hi, are there special considerations for wood stoves in A Frame houses? I am looking for the best installation method. Thanks so much.
Torri
Hi Torri,
Yes there are some important issues to deal with. First, don't attempt to place a stove against one of the sloping walls and run the chimney out through the wall/roof far down the slope. If you try that you'll end up with a very tall chimney outside the building and providing stability will be difficult if not impossible.
You do need to penetrate the sloping roof in order to keep the venting system inside, but do it near the peak. By far the best approach is to locate the stove near one of the gable ends and mount the chimney in the roof just below the peak. That will keep the venting system mostly inside the building where it will stay reasonably warm and will provide the most stable, least ugly chimney installation. It will also mean you can do the installation from ladders instead of scaffolding.
John
Boosting efficiency with a flue pipe mounted heat reclaimer?
I'm curious whether there are after market secondary heat exchangers available as accessories for residential use to be used to upgrade older pre-high efficiency wood furnaces. I'm just trying to find a way of harnessing those hot flue gases before they all escape out my chimney. Is ther anything short of actually buying a new furnace? Our old one still works but is extremely inefficient and sends a lot of hot gases up the chimney (especially in the coldest weather when we've got a large fire going.
Kevin
Hi Kevin,
Retrofit flue pipe mounted heat reclaimers used to be popular until it was learned that all they do is plug up with creosote. In Canada they are banned outright because of the hazard they represent. Advanced technology, high efficiency heaters don't achieve higher efficiency by extracting more heat from the flue gases, but by burning the wood more completely. Moreover, the chimney is the engine that drives a wood combustion system and it needs heat to work. You'll boost efficiency more by concentrating on burning the wood completely without smoke than by lowering flue gas temperature. You'll get higher efficiency by using the ideas you'll find in our Tips section.
John
BBQ starter as a chimney primer?
Hi! On occasion my basement will fill with smoke when I try to light a fire - fortunately, this doesn't happen too often, even though the woodstove is located in the basement and the metal chimney runs up the outside of the house from the basement (lucky me!).... Anyways, I was wondering if it would be okay to use one of those electric BBQ starters to warm the chimney up? (fyi - the kind of electric BBQ starter I'm talking about is a coil of metal that gets red hot when plugged in). Thanks!Rich
p.s. I love your site & visit it often!
Hi Rich,
I suspect an electric BBQ lighter might work, but it is rather energy intensive and maybe time consuming. And depending on how powerful your backdraft is it might not even work because the rush of cold air coming down the chimney prevents the hot air from going up. I have heard of people having success with hair dryers, usually pointing them up a chimney cleanout door, because the fan helps to drive some hot air upward.
But the normal approach to correcting a cold backdraft before attempting to light a fire is to open the closest window or door. This neutralizes the negative pressure due to stack effect that sucks cold air down the chimney. In most cases with the window or door open, the chimney flow will turn around immediately. Once the fire is lit and a little heat gets into the chimney, you can close the window or door.
Try the open window approach. It tends to be quicker and consumes no energy except for a little heat loss.
John
Chimney Failure
I have a franklin stove in my basement, which is in the new addition of my home. The chimney is stainless, triple wall and runs inside the house along the outside wall. I have a terrible problem with downdrafts, until the chimney warms up. The new addition is not as tall as the old section of my house, so the chimney is a lot lower than the peak of the old section. I've seen when it really got cold that the chimney above the stove has been white with frost and the damper frozen solid. Should I raise my chimney up or what?
I would really like to use my stove, but my wife hates to get up in the middle of the night to smoke detectors and a house of smoke when the fire burns out. Any ideas will be much appreciated
Thanks, Steve
Hi Steve,
You are suffering from a classic type of chimney failure. You have diagnosed it exactly right. At standby with no fire in the stove, your house acts like a better chimney than the chimney. That is, the stack effect created by the warm air in the house creates a slight negative pressure down where the stove is and because your chimney is shorter than the house, it cannot compete, so it flows backwards. The phenomenon is explained in our Chimneys section.
Chimney physics is working against you. The only sure-fire reliable way to fix the problem is (believe it or not) to change the relationship between the chimney and house by moving the stove to the part of the addition next to the tall part of the house and run the chimney up through the warm space. This will make the chimney outperform the house as a chimney when it gets cold outside.
Just raising the chimney is not likely to work. mainly because heat loss in a tall chimney exposed to the cold is so great that the chimney still can't compete with the house. A theoretical alternative is to 'trick' the chimney into thinking it is inside the house and at the same time raise it to be taller than the house. This would involve building an insulated chase around the chimney.
But your chimney is air-cooled, which means it will be cooling itself, whether you have a fire on or not. Air-cooled chimneys can be very bad, and your case is a good example of why they should never be used. The only benefit of an air cooled chimney is that it is cheap. But it is a truly lousy chimney.
Filling the house with smoke in the middle of the night is just totally unacceptable, not to mention hazardous. And besides, Franklin fireplaces are truely awful wood burners that smoke and overfire and tend to disappoint their users. If that were my system, I'd take it out and start again. And I'd use a solid-pack chimney.
John
Fireplace Chimney Problem
I have a problem with the chimney for my 40-year-old split-level house in Toronto, Canada. The chimney is outside the house and has three flues (2 for two fireplaces [main floor and basement], 1 for natural gas furnace/water heater). The chimney has been rebuilt by a previous owner above the roofline once before. The bricks are spalling above the roofline and breaking apart. We have installed glass doors on the main floor fireplace to prevent smoke from escaping into the room. We currently don't use the basement fireplace.
I am planning to have the chimney replaced above the roofline with matching bricks, new crown, rain cap and install a stainless steel chimney liner for the furnace. While we get this work done I was wondering what we could do to make the fireplaces more functional? The chimney is on the lower half of the split-level - should the height of the chimney be higher than the roof of the taller side of the split-level?
Would you recommend installing a new hearth? Will the basement fireplace ever be able to be used practicably or would it be better to convert to gas? Is it feasible to expect that we not need the glass doors, as they do not allow the heat to escape?
Sorry for all the questions but I hope you can help. Thanks, Darren
Hi Darren,
This chimney has both of the worst possible characteristics. First, it runs up outside the house and second, the chimney penetrates the house envelope below its highest level. Both of these problems are explained in detail in our Chimneys section.
There is no good solution because both problems are created by the relationship of the chimney to the house. You're not alone; these problems plague North American housing.
By all means, install a liner for the gas furnace. Better still, replace the vertically vented gas furnace with a condensing or sidewall vented one so there is less risk of exhaust spillage into the house.
As for the fireplace, considering you are in a city, you might want to consider a direct vent gas fireplace insert; do not let someone talk you into a B vented insert, which tends to be a little cheaper. If you want wood and you want heat, install an EPA certified fireplace insert with a full liner. I would suggest you forget about glass doors or an open fireplace, unless you don't highly value your health and safety.
John
Outside chimney causes problem?
I just bought a home with a 40', metal, outside flue for the fireplace. It's in Vermont, USA. Am I in trouble from the get go here? From what I've read, I have two things working against me.
1. The flue is outside.
2. It gets to -15 deg F here sometimes.
Any thoughts, help, leads?
Hello, I think your assessment is correct. When the temperature in the flue falls a few degrees below room temperature, the house will begin to function as a better chimney than the chimney, and air will be sucked down the chimney by the negative pressure low in the house due to stack effect. The actual frequency and severity of cold backdrafts in any given system depends on a lot of factors, but the taller the system and the colder the weather, the stronger the backdraft and the harder it will be to correct.
Some people recommend installing a chase around the chimney to keep it warm, but I've seen enclosed chimneys backdraft because the chase leaked cold outside air and because, without heat input from the house, even the inside of a chase will eventually cool. If you have a very strong backdraft, I wouldn't recommend a chase, unless you want to spend a lot of money on it.
I would investigate re-installing the system inside the house. I know that sounds outrageous, but it can, and has been done. On the other hand, if this is a cheap factory-built fireplace, then its poor performance wouldn't likely justify the expense, even if it worked to its potential. You could save up your money and install a good EPA certified fireplace and be able to view the spectacular fire and heat a good part of the house with it, but only if you relocate the chimney.
But, I guess the best thing to do is try it this coming winter and see how much of a pain it is to live with. With a system like yours, with a high potential for strong backdraft, my worry is that, even if you could get a fire burning, as it recedes to a coal bed the system could go into a hot backdraft and fill the house with smoke and carbon monoxide. This is why correcting a cold backdraft by temporarily opening a nearby window to neutralize stack effect is sometimes not such a good idea. Good luck with it.
John
Chimney Height and Draft
Could you tell me the right way to draft a chimney? Is the higher the better or the lower height or how high above the roof should it be?
Thanks, Keith
Hi Keith,
The chimney should extend at least 3 feet above the roof surface it penetrates and 2 feet higher than any roofline or other obstacle within a horizontal distance of 10 feet.
Two things determine chimney draft:
1. chimney height
2. flue gas temperature
Taller chimneys make more draft, but chimneys exposed to outside cold don't. See our section on chimneys.
John
Proper Height of Flue
We have inherited a good woodburning freestanding fireplace to install in a section of our home but we don't know how high the flue should be. The flue outlet is around 22cm square. The hearth/grate is 80 x 50 x 50 cm. The room has a flat roof about 2.7 metres from the floor. Is there an equation to calculate height and size of flue needed? We don't want a very tall flue unless its is absolutely necessary as we get high winds in winter and want to avoid excessive bracing. Your help will be appreciated
Felicity
Hi Felicity,
First, the top of the chimney must be at least 1 metre above roof level to prevent excessive turbulence. Secondly, a good rule of thumb suggests that system height from hearth level to the top of the chimney should be at least 4.6 metres. It looks like you'll need at least 2 metres of chimney projecting from the roof. Flat roofed single-storey buildings are always a problem with chimney height, but I would strongly recommend meeting the 4.6 metre objective to help prevent smoke spillage into the house.
But the more important issue is that freestanding fireplaces are terribly inefficient and usually smoke into the room. I would suggest that you take the fireplace to the dump and buy yourself a decent appliance.
John
Shared Flue?
Can a woodstove share a central single flue masonry chimney with other natural gas appliances (boiler furnace and water heater)?
Thanks, Paul
Hi Paul,
In a word, no. Most codes prohibit co-venting wood and gas, and for good reason: their draft requirements are entirely different and incompatible. The draft hoods on the gas appliances bleed off draft to the point where you could hardly get the stove to run at all, and it would smoke like crazy if you opened the door. Gas appliances prefer almost zero draft at the burner and wood stoves like lots of draft.
A wood stove needs its own chimney. And besides, a wood stove should never be put in a furnace room. Wood stoves are space heaters and so should be installed in the space to be heated, not hidden away someplace in the basement.
John
Suppliers of Chimneys
We're interested in installing a woodstove and are wondering what places (online, presumably) are best for us to learn about and purchase the stove pipes we will need. Is there possibly a Canadian company, where we might get a better deal with a favourable exchange rate? Thanks, Lisa
Lisa,
When you say stove pipes I assume you mean chimney, as distinct from the flue pipes that run between the appliance flue collar and the chimney. I think you should read our chimney section before going any further.
Price should not be your first concern – safety is what is important.
By the way, I have never seen anyone, including me, install their first chimney perfectly. Anything less than perfect might not be safe. I would strongly recommend that you ask the most experienced person you can find to give you a quote, then take it from there.
Yes, there are Canadian companies and Canadian suppliers all over the country. I don't know why you are concerned about exchange rate. People in Canada rarely install US chimneys, unless they are part of a fireplace.
John
Money Saving Wood Stove Chimney? NOPE!
Hi, I am planning on installing a wood stove this fall and have a question on the chimney. I will be installing the chimney in a 25 foot tall framed chase with inside dimensions of 18 inches by 60 inches. A chimney installer informed me that I could use a stainless steel liner with a zero clearance (some sort of fiberglass wrap) instead of the costly triple insulated stove pipe. This sounds great to me if it is an safe substitute for the stove pipe.
Thank You, Scott
Scott,
The plan sounds hazardous to me. Are you sure your chimney installer wasn't thinking about relining a masonry chimney? It is inconceivable that any responsible installer would suggest that you could install an insulated liner in a framed chase, considering the house would likely burn down in short order. These are liners, not chimneys; they need to be installed in a brick enclosure.
I do hope you reconsider. Your plan to save money sounds extremely dangerous to me. If you value your house and your family's safety, save up your money and buy a proper solid pack insulated metal chimney. Maybe you should seek out someone else to advise you.
John
Adapting Chimney Sizes
I've taken over a "hippie homestead" in Manitoba, and in order to get insurance I'm going to have to upgrade the chimneys to the "2100" type (2-inch insulation). Fair enough - I'm all for safety!
The main heater is a Triumph with an 8" collar which has been adapted to a 7" chimney. (The stove had a label, which is now gone, so I can't offer specifics.) I may want to, or have to, replace this stove as well, as I would think there are better designs available now, and I'd like to keep emissions to a minimum. Something EPA certified or whatever.
It seems, from a cursory investigation (there are no serious stove dealers within 200km of here) that newer stoves most commonly have 6" collars. Maybe this impression is skewed due to the small data sample. ;-)
I don't want to put in a shiny new chimney that's inappropriate for the present stove or a later stove acquisition. The two goals may be incompatible.
Question: Presumably it's best to have the same chimney size as the stove collar. If forced to adapt sizes, which is the lesser of two evils - large stove into smaller chimney or visa versa? (If nothing else, this will tell me something about the quality of the existing situation.)
My technician's guess (I've no experience in wood heat systems) is that, to a point, a smaller chimney would have greater flue-gas velocity and be less prone to creosote accumulation, even though at first blush the idea of a slightly oversized chimney is intuitively appealing to the neophyte. One way or the other, I suspect that if the size difference is too great, one eventually gets into trouble of a different kind.
I'm thinking I should bite the bullet and buy stove and chimney at the same time, but as I know so little and the suppliers are at such a distance, I don't want to rush into this. Meanwhile the nights are getting chilly.
BTW, I'd love to hire a qualified stove supplier / installer to take care of this but they're not easy to find here, and I shudder to think what it would take to get one out here from a distance. When you ask about installers, people look at you as though you're from Venus. The idea that you wouldn't put in your own chimney is borderline bizarre to them. But they've grown up doing this stuff, whereas I've grown up with thermostats. ;-)
Cheers, Scott
Scott,
Your intuition is right. Better to use the smaller 6" chimney. Best to install a new EPA certified stove with it, but barring that use the 8" Triumph on the 6" chimney, adapting from 8" to 6" at the bottom of the chimney (ie use 8" smokepipe to the chimney base) for pretty much all the reasons you mentioned.
Cal
Scott replies:
Thanks very much indeed. Just yesterday the insurance company in question confirmed this as well.
The old Triumph doesn't seem like a bad stove, though I know a newer unit would be a good investment. I've just moved in here though, and I'm trying to spread the cost of upgrades out a bit! That much more important not to close doors on myself.
Thanks sincerely for your help.
Cheers, Scott
Flue Temperatures
I'm attempting to find the usual operating flue temperature ranges of woodstoves and fireplaces. Also if clay liners have a tested operating temperature.
Thanks, Miro
Hi Miro,
Flue temperatures are highly variable because of differences in appliances, venting systems, fuel and operating conditions, but the range would be from ambient up to about 2100°F. A system operating normally will run between 200°F to 1000°F, depending on where and when in the burn cycle you measure it.
The clay liner standard only says that they must not soften at 2100°F. There is no performance test for clay liners. They tend to fail because of thermal shock caused by rapid temperature changes like those that happen during a chimney fire.
John
Odor Busters Please!!
I have a "heat-a-lator" type fireplace installed in the basement of my single story home. The chimney is a masonry type with clay liners and brick exterior on an outside wall. The liners are 12" as recommended by the fireplace manufacturer.
I didn't use the fireplace for many years after it was installed until I finished the family room in this area. After the first fire I burned and the chimney had cooled down- I had a very strong sooty smell enter my fireplace and family room from the chimney-even with the damper closed! The chimney worked properly while the fire was started and burning. It had plenty of draft and is covered at the top with a chimney cap.
My question is: Do I just need to burn more fires to "condition" the chimney to burn out excess moisture, etc. that may have settled in over the many years of not being used? and Are there any chemicals that can be used in the fireplace to help eliminate these odors? (I know after reading your articles that my main problem is the chimney is located on an outside wall and is not insulated)
Any comments would be appreciated- because I love a burning fire and no odors afterwards and my wife said divorce court was next if those ghostly odors entered the house again. Thank you! Ron
Ron,
I'm sorry to say there is no simple solution to your problem because it is, as you say, caused by the relationship between the chimney and the house. You can use baking soda or equivalent to reduce the smell, but this only works if you clean the system thoroughly and then don't use it any more. Here are some options;
- install a sealing damper at the top of the chimney to stop the backdraft between fires (Lymance and Locktop are popular cable operated brands) (fireplace throat dampers don't seal well at all)
- install a fireplace insert with a full stainless steel chimney liner; this will reduce backdraft volume and intensity, convert the fireplace to a serious heater and the chimney liner will tend to isolate the flue from outside cold.
Those are my best suggestions. Good luck with it and I hope it doesn't end in divorce.
John
What's best: masonry or metal chimneys?
I want to know what the lifespan would be for an outside the house woodburning chimney made of block and tile as opposed to insulated stainless pipe.
The life span of a masonry chimney depends a lot on how it is used and maintained. A severe chimney fire can blow the tile liner instantly and a failure to maintain the cap or crown every year or two can allow water in. If you live in an area with freezing temperatures, this can lead to rapid deterioration. Well built and maintained, a masonry chimney can last a long time. Note that concrete block shells are not nearly as good as brick because a) they absorb water and break up with freeze/thaw cycles and b) they are less stable because there are fewer interlocking joints that key the structure together.
On balance, of all the chimneys that are acceptable under building codes, a concrete block chimney is the worst. The fact that you intend to put it outside, which we strongly discourage, makes it a truly lousy option.
Metal chimneys are well proven and most have parts warranties. They tend not to need the same level of maintenance as masonry in order to last a long time.
In short, either option can be effective, although on balance, we tend to favor metal over conventional masonry because it tested, certified and has some insulation to keep the liner warm.
John
A question about steel chimney liners
Hello, I found your site helpful and interesting. Our home in Massachusetts is entirely heated by wood. The house is very well insulated, and it is only 15 years old. I had the local chimney sweep come to clean, and he says we need a steel liner installed inside our chimney -- for about $3000 (two flues). We do normally burn with the choke pretty tight, so it's not very hot in the chimney. But I am surprised that such a young house would need that kind of repair. What is your take on steel chimney flue liners? How do I get an unbiased opinion? Andy
Andy,
Stainless steel chimney liners are widely used and have been for more than thirty years. They are a great way to upgrade failing masonry chimneys. Masonry chimneys can fail in as little as three years, depending on how they are used. I would recommend that you get another liner estimate, just to make sure the price you have been quoted is fair.
Choking down woodburning equipment is the main way to destroy chimneys, both by being the main cause of chimney fires, and also by permitting water condensation in the chimney, which is really destructive. You should try to avoid smoldering fires because of the damage they do to your system and to the environment. You might want to read the articles in our Tips sectioin.
John
Connecting to a two flue chimney
I would like some info. on connecting wood stove to my chimney, which has two inserts. I already have a gas furnace in one of the inserts, so can I put a woodstove in the other one?
Thanks, Beth
Beth,
To get the terminology correct, you have a chimney containing two flues which are the holes through which flue gases flow. Chimney liners (not inserts) surround the flues.
In answer to your question, yes, you can connect a wood stove to the other flue, provided it meets code requirements. You really need some local assistance to make sure the connection would be effective and safe. Chimney sweeps are good at checking out existing chimneys.
John
Bad smells from a basement stove
In the past 2-3 months we have been having problems with our wood stove. It is located in our basement. We have been awakened in the middle of the night to the heavy smell of creosote. My husband has cleaned the flue and replaced the pipe from the stove to the flue. We have had the stove for 3 years now and this is the first time we have had this problem. Also, since he replaced the pipe this last time, it is dripping creosote where the pipe fit together.
Thanks for your help.
el
Hi el,
It is difficult to diagnose this kind of problem without seeing the system and the house, especially since you haven't given much information. It sounds like you are suffering a cold backdraft, normally linked to installations in which the stove is installed low in the house and the chimney runs up the outside wall. See articles in our Chimney section.
If someone in your household likes to sleep with their bedroom window open a little for fresh air, this may be the problem. Any leaks high in the house will make a cold backdraft more likely and more powerful. I would strongly recommend that you get a chimney sweep or stove/fireplace specialist to inspect the system and advise you.
Also, since you report dripping creosote, it is likely that the stove is being allowed to smolder. You might also look for sources of high moisture in the house, like a large amount of firewood or laundry hanging to dry. Low flue temperatures due to smoldering is a common reason for failures to vent smoke properly. You might want to read the articles in our Tips section to learn how to keep flue gas temperatures higher.
John
Joe's got an outside chimney – NOW what can he do?
So I blew it and built a metal chimney outside the house enclosed in a frame chase. I assume I will have the backdraft problems you spoke about in your "evil outside chimney" paper. What can I do now? Would putting some kind of blown in insulation into the chase around the pipe help?
Thanks, Joe
Joe,
Yes, your system will be prone to cold back drafting, but before responding I need to deal with the issue of insulation around the pipe. If you really did that, rather than just use fiberglass batts in the spaces between the framing studs of the chase, you would likely burn your house down. The air space around chimneys must be maintained or they will overheat. Please do not blow insulation into the cavity. If you want to insulate, only put it between studs. Also, insulation and air barriers in chases must be contained by sheathing to prevent them from heating up and falling against the chimney.
A number of things affect how strong cold backdrafting can be, and how big a problem it is, such as:
- How cold is your climate? The colder the climate [or weather], the stronger the backdraft. Houses in Canada and northern tier US states suffer powerful backdrafts. People in southern states don't [but, of course, they have other problems]
- How tall is your house and chimney? Taller houses and chimneys backdraft more aggressively. This is why basement stove backdrafts seem stronger than main floor stove backdrafts
- Where are the leaks in your house? The higher the leaks, the stronger the backdraft. If you have a leaky attic hatch, lots of high level recessed light fixtures, forced air heating ductwork in the attic, or you like to sleep with the second floor bedroom window open, you'll have stronger backdrafts.
The really bad thing about outside chimneys is that the remedial measures are either ineffective or unappealing or expensive or all three, which is why we tend to be strident about not installing chimneys outside in the first place.
Consider the following comments in the context of the three points made above.
Insulating the chase might help some, but a large component of heat loss from typical chases is from leakage, so sealing it [including top and bottom] is at least as important as insulation. The only way to really fix an outside chimney is to trick it into thinking it is inside. That would mean a chase that is the same temperature inside as the house is so the chimney stays warm enough to compete with house stack effect. With a really well sealed and insulated chase, you could vent it into the house, with a couple of passive vents at top and bottom of each storey, so that a convection current would keep the inside of the chase nearly as warm as the house. That strategy is the only one sure to work, and then only if it is done well
On the other hand, if your climate is reasonably mild and your house is reasonably short and if its leaks are relatively low and you keep fires burning most of the winter and you burn the wood bright, hot and clean, you might never have a problem with cold backdrafting.
John
When it's windy, we have a smoky house
We installed a new woodstove with an existing chimney when we moved into our house three years ago. Last spring and this winter, we have been having problems with smoke coming into the house through the stovepipe joint where it enters the ceiling. When it first happened last spring, we thought it was possibly because of a pressure inversion. This winter, however, we seem to have a smoky house any time there is a wind. Our chimney is straight, inside in a one story addition to a one and one half story house. We clean the chimney frequently (approximately 5 or 6 times/winter). Do you have any diagnosis for the problem, where we can get help, and how we can fix it? We didn't have this problem the first winter we were here.
Thanks, Ed
Hi Ed,
Problems of this kind are so complex that I could spend a long time writing to you about possible contributing factors. I can't do that. But here are a few ideas.
1. A chimney installed in a single storey section of a two storey house has to compete as a stack with the house, especially when no fire burns or when chimney temperatures are low like when the fire smolders. This may not be the main cause, but it weakens the chimneys ability to flow air and gas up under all conditions.
2. You need to pay attention to which wind direction leads to the problem. If spillage happens when wind blows from the single storey side, you need to look for leaks on the downwind side of the house on the two storey side, especially high level leaks like open second floor bedroom windows or a leaky attic hatch. This situation can depressurize the house and suck flue gases down the chimney into the room.
3. Smoldering fires are a key cause of this type of failure. Make sure that you burn small, hot fires and don't let the fire smolder. The wood should be flaming until it is reduced to charcoal.
4. If there is no cap on the chimney, get one; open chimneys are extremely vulnerable to adverse winds. Raising the chimney might help to get the top of it up out of a zone of positive pressure caused by a wind effect.
Ideally you could contract with someone who can come to your house and diagnose this, but such people are hard to find. Check first with local chimney sweeps or long-time stove and fireplace retailers.
John
Stainless steel liner in a masonry fireplace chimney
What options are available for fireplace flue repair? We are working on a project where there are two existing fireplaces, roughly 75-80 years old. The owner would like the fireplaces restored. Can stainless steel liners be used on wood burning fireplaces? Jim
Hi Jim
Yes they can, but it is not an elegant solution because the connection above the throat and damper are difficult to do and rarely done well. Since we at woodheat.org think wood should not be wasted just to watch it burn, but should provide an energy benefit by delivering heat to the room, we would recommend the installation of a fireplace insert with a full stainless liner to the top of the chimney. In this case the liner is sized to the insert, not to the fireplace, and the connections can be secure and permanent. An additional benefit of an insert is that it would improve resistance to smoke spillage into the room and reduce outdoor air pollution from the fireplace. This is the only environmentally responsible solution, in our opinion.
If your client insists on retaining the conventional fireplace for historical or nostalgic reasons, a far better solution than stainless steel is a solid-set poured-in-place lining system. This insulating cementatious material greatly improves the structural integrity of the chimney and improves performance by insulating it.
You need to find a supplier of SolidFlue, Arens, Golden Flue, Supaflue and there may be a couple of others that I can't think of at the moment. Chimneys sweeps can usually tell you if there is a local supplier.
John
A fireplace cannot share a chimney
I bought an old house in Philadelphia. The heating system is gas, hot air. There are two chimneys. One vents the heating system and air conditioning; that one is in the living room. The other vents the hot water heater. I would like to add a fireplace in the living room. I would prefer wood. It would need to be very small, as the living room is 14 X 16.
Is there some way to utilize the chimney that vents the heating system? If not, how expensive would it be to install a new chimney for a wood burning fireplace (ball park figure is OK). The house is two stories and very small.
Am I better off with a direct vent gas fireplace? Any advice would be greatly appreciated!!! Susan
Susan wrote,
“Is there some way to utilize the chimney that vents the heating system?”
No, you can’t use a chimney for both a fireplace and heating system.
There are many factory-built fireplaces on the market of all shapes and sizes. They don’t need a foundation, can be put almost anywhere and routing a chimney up through the house is done all the time without problems. You need to visit a few fireplace retailers, see what they have and what they have to say.
“Am I better off with a direct vent gas fireplace?”
We are not the right people to ask about gas fireplaces. Since most everyone else will advise you to go gas, including most fireplace retailers, I will suggest that if you want a real fire, the only option is wood.
John