I took this picture of our wood stove chimney. Once the little Jotul F100 wood stove gets hot this is the way it looks:
wood stove chimney with fire going
Clear. According to the US EPA certification sheet, (large .pdf file) the Jotul F100 Nordic QT puts out less than 3 grams of particulate matter an hour.
non catalytic wood stove diagram
Very little particulate matter is released from this stove because it has a baffle. When the fire box is above 400 degrees or so, all of the smoke is burned in a secondary combustion because the baffle mixes the wood smoke with fresh air at a combustible temperature. This means that the stove is much more efficient, safer, and better for the environment. If the smoke were not burned it would condense as creosote on the inside of the chimney.
Jotul F100 Nordic QT wood stove at operating temperature
Wood creosote is a brownish yellow sticky substance that is essentially condensed wood smoke. Since wood smoke is combustible, wood creosote is also combustible. In fact, it is a bad hombre, leading to chimney fires that can burn down a structure. It is the reason why every wood burning appliance needs to have it’s chimney cleaned and inspected annually.
A properly installed, clean burning, UL listed, EPA certified woodstove is good for the environment as they produce no nitrates or sulfates while operating. They are a great way to save some money on heating, especially if the wood source is free.
Great post. I found it to be very useful. I will have to bookmark your site for future reading.
Very good explanation of combustion. What I like best is how you break it down so a first grader can understand. Or is that 5th grader? LOL
Wood Stoves Guide
Thanks for sharing the photo and the graphic image too. Sometimes it becomes impossible to really understand what the author is talking about. But you made the point to post the photo and it’s graphic too. Also the stove itself looks very creative in design. Thanks for sharing this.
I have reviewed your comments and yes many stoves have changed the internal air flow designs for cleaner burning. Does your stove smoke during start-up and for what how long..how many minutes etc. and at what temperature do you achieve the clean burn you have photographed from the chimney stack? How long does it take for your stove to heat up and or click on the auto fan and or reach the surface thermometer temperature of 200 to 300 degrees indicating stove surface temperatures and a clean burn rate? Is your stove lined with fire brick and what comprises the baffle system, steel, firebrick and or insulation blanket? I know these are lots of questions and I am curious.
To answer your questions:
1. The stove does smoke on startup. It takes about 10-20 minutes for the stove to get to 300 degrees, at which point most of the smoke stops. Another 10 minutes and it is at 400 degrees, which is were I took the photograph of the chimney.
It is a cast iron stove, no brick, or anything else
This is about normal. Your documented temps of the stove.. are they from a thermometer on the stove top surface or side or are you using a digital laser? I am glad you do not have fire brick on the inside. What are they using to protect the metal from the internal heat of the fire inside the stove..if anything? Are there any fire bricks on the bottom? What were you allowed clearances for install 8″ or more to combustibles back and side etc.? Thanks
Paul,
I went ahead and downloaded the manual for the stove. You have a very nice stove my friend. It is built like a tank and the cast iron construction is a great heat sink and conductor of heat. Your clearances are a little wider than others and that would be because of the radiant heat transfer capabilities of the unit. Had they had shields for the sides and back available to install on the unit…. you could have been installed closer to combustibles. Clearances are still very good. The heat this stove throws out must be huge when at top fired temp of 600 degrees. I was curious because I own several Quadra-Fires and they are the same stove at varied years of production. They have done somethings wrong in the design construction and also restricted airflow in order to reach EPA standards. These units use firebricks to protect the steel plate and this takes away from the heating abilities of the stove as well as the efficiency of the heat transfer..which in turns ends up costing the consumers more wood for like heat compared to your Jotful. I have had to revamp these stoves a little to achieve better heating capabilities.
I have a thermometer on the top of the stove, I have also used the digital laser. I like the thermometer because it assures me the stove is operating correctly. Generally, I run it in the 400-500 degree range, and yes it does put out quite a bit of heat. Last night it was 10 degrees F outside, with the stove running, the house was 72 degrees and the furnace did not run all night.
All in all, it is a good little stove. If I where heating the house full time with wood, I would get a bigger one though. My only complaint is the fire box is a little small and won’t take a good wood load that will last through the night.
paul,
Glad to see you were warm last night:) Yes a larger box and overall size stove would be nice for the overnight burn. I have taken the firebrick out of my stoves and placed it on top of the stove…not sure it helps.. but if I want a heat sink… I think it is best inside the room and living area… than being installed inside the stove…where the stored heat just exists out the flu. I have heard water is a great heat sink and holds heat very well…that is one reason we put a kettle on them…moist air has a warmer feeling than dry air. I have stored water bottles close to the stove and this has increased the warming of the area and I am thinking of buying metal jerry gas cans…that I shoud be able to fill with water and then place on the top of the firebrick on the stove…hopefully creating the ultimate heat sink and slow release of the stored heat….for a longer period. Bigger stoves =more wood=more heat=longer hotter burn times.
Stay warm…this global warming is costing me and probably you an arm and a leg in propane costs……
Paul,
Can you comment on, or give reference to stainless chimney liners and fireplace inserts?
This house I just bought has a fireplace. I have had free standing wood stoves in the past and I was very happy with them. Like you, I know I could heat the coolest of house with one. Matter of fact, heat it well enough to run around in shorts.
I’ve had my chimney cleaned and inspected with a clean bill of health. However, in the fire box I have noted some 1/4inch cracks in the mortar which makes me wonder if it’s safe. It is a full brink (from inside to outside) fireplace. I have had mixed comments on the stainless liners though.
My thoughts are to have an insert installed as well as a stainless liner.
Your thoughts or comments please?
Fred
One of the big problems with a wood stove is that you can’t put it in a mobile home — it’s just not safe. We finally worked around this by getting an exterior wood stove that sits outside the trailer but feeds hot air into the house. Works like a charm!
Paul,
I see the last comment I posted has left the building….did you not like the idea of using water as a potential heat sink on the top of or by the exterior of the stove? I did exactly what I said I would do.. and it cost me 50 dollars for two each jerry metal cans….and I am now in heaven. Stay warm…
Fred,
Have the exact same set-up…I will comment if you wish. I had mine relined last year.
Obewan,
I am open to comment, for sure.
Thanks,
Fred
Hi Fred, Sorry for the delay, it is the time of year when time is in short supply…
I have seen some very nice wood inserts, Jotul makes a few, that are highly rated. The advantage of an insert over an open hearth is much less heat is wasted because there is no open flue. Like wood stoves, modern inserts requires suction (stack effect) from the chimney to maintain good airflow into the fire box and thus good combustion. Older brink and mortar chimney’s take a lot of heat to get to a good operating temperature.
Insulated stainless steel (Class A) chimneys have the advantage of less mass, better insulation and quicker heating times. A good hot chimney will not condense any creosote and thus be safe. Last two years I cleaned my woods stove chimney, it had nothing but fine black soot. Creosote is brown and gummy. I have seen brick and or stone chimneys with creosote running down the outside of them because they are operating too cold.
A good stainless chimney liner will likely make a wood insert work much better, however, consult the manufacture for more information. If you have a good woostove shop around, they may know too.
Good luck! Merry Christmas, I hope you and yours have a good holiday season and a happy New Year!
Fred,
Paul has pretty much covered the basics of why and what. I am not familiar with the Jotul inserts but based on the pdf on Paul’s stove if they are cast iron and constructed the same ..they would be a great wood stove insert. Some of the basics are that any fireplace brick chimney half in and half out of the house was not a good design for anyone anywhere when they were built. Not sure why they are so common and they are not efficient in holding heat in the heat sink interior walls or keeping chimneys or tile flues up to proper temperature as Paul has explained. Even the heatilators constructed inside some of the interior brink facia in most of them were poor at best in design and function. Wood stoves and fireplaces etc. need to be in the center of the house if at all possible for best results.
Your fireplace does not appear to have steel installed on the interior and that is good. If you did that would have to be torch cut in order to open a hole to make access for a double wall reline pipe extending down to the wood stove insert. The wood stove insert you buy will determine the size of the reline double wall pipe to buy. There are single wall S/S flex reline pipes you can buy on the internet and they are much cheaper than fixed double wall. Depending on codes in your area you might be able to use one. However code usually requires these to be wrapped in a thermal blanket anyway. So a relined fireplace chimney will improve draft just due to the smaller hotter chimney pipe. The fireplace chimney with clay tile will take a longer time to heat up and will generate more creosote buildup on the interior of the chimney.
I currently have a 30 year old 28000 Buck stove insert that required an 8″ reline pipe. I purchased this one.http://www.duravent.com/pdf/catalogs/duratech.pdf. This was actually a pretty easy install after torch cutting the hole in the steel heatilator I had in the original fireplace and then removing the damper plate. Here is a general link on chimneys. http://www.woodheat.org/chimneys/aboutchimneys.htm
Some basics are that in a fireplace wood stove insert you want the heat to transfer to the stove surface as quickly as possible to activate the stove fan. It is this fan that delivers you the heat from the wood stove insert into the room area. When installing the wood stove insert be sure to plug and block any area directly above the wood stove…if you do not… the heat not being picked up by the fan will exit straight up your clay chimney and out the top of the chimney. I used and cut a piece of galvanized roofing and sealed the entire area directly above the stove insert in an attempt to keep as much heat as possible at the immediate internal stove area. I will in the future probably install channel and lay firebrick on top of the Buck to reflect heat back to the stove fan. This will be done directly above the stove and behind the surrounds that enclose the fireplace around the wood stove insert. Keep as much heat right at the stove as possible. You might be able to get the brick facia heat sink to heat up a little and this helps radiate some of the heat into the room. Most new stoves have firebrick installed on the inside and I have found no reason for it except to protect the metal of the stove. Plain steel or cast iron is the best. Some firebrick on the bottom maybe or lower areas if you want protection for the steel otherwise remove it all. Heat is trying excite the steel and then push heat through it to the other side where the fan wants to activate and pick it up…firebricks are very hard to push heat through and you will be only wasting heat up the flue and burning more wood to get the desired heat you want.
Hope this helps and any other questions let me know..The Buck is actually a great stove.
So now that I am getting information I have another question, if you all care to entertain.
I saw a picture of a small free standing wood stove placed on the hearth and the stove pipe going into the fire place and up the chimney. It would seem that now you have the full 3D surface area of the stove to heat the house. Is there something wrong here or is that a viable option?
Thanks,
Fred
Fred,
Yes a vary viable option. #1 You will have to remove the brick and the cut the interior chimney flue tile creating a hole in the original chimney. #2 You may be able to drop down to the floor in front of the hearth and by extending the floor protection you might be able to go right up the fireplace opening. Most stoves do not exit from the rear and this second idea would I think require a rear exit stove pipe.
Then you have to evaluate the look and function of what you are creating and then any long term resale ramifications caused by your decisions. I think if your fireplace has no steel lining inside the only thing you may have to remove is the damper rod area. If this is the case the second concept would save the original chimney tile flue and fireplace for reuse possibly down the line if desired.
Yes in either case..fan forced 360 degree heat is better than fireplace fan heat. You would be surprised just how much heat my old Buck stove does kick out. The problem is the fireplace was installed at one end of the house in a great room kinda and it is a long rectangular ranch. No way can I get this heat to the other end of the house unless I install ducts and slow moving draw fans in the attic etc. to pull heat to the other rooms. If yours is set up the same way..any heat will be hard to get to the other rooms…
Another option is possibly to just install and drop a free standing wood stove somewhere else inside the house. Mine had no room for such a move. I did install one in my garage this year…and at least I am warm in there.
Wishing you a great Holiday!
I have just purchiced a new legend wood stove and i have a really bad problem with creosote the bottom vent is full and its hard as a rock i was wondering if anyone has a suggestion on how to remove that stuff
Nice article! Good shot of the chimney, many people don’t realize the important role that it plays in wood stove operations.
I’m glad some people understand the great value that wood stoves offer! And like one of the posters commented, the high quality models are built like tanks, so they really do provide lifelong supplemental heat.