wood burning insert?


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Old 12-24-08, 12:57 PM
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wood burning insert?

We have a fireplace and love making fires.
Some of our freinds have the wood burning stove inserts that install into the fireplace, and stick out somewhat.
We would consider one of these to help heat the house if it looked more like a fireplace (did not stick out).
Our fireplace does have 2 lower and 2 upper vents - no electric blower. The 2 upper vents do produce warm air but only after the fire has been on and hot for a while.

Any suggestions?
 
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Old 12-24-08, 04:23 PM
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The skinny on fireplaces vs insert. Most of the public does not know how to burn a fireplace efficiently and how to re adjust the damper.
Open damper fully to start
Once desired fire is reached get down and look sideways across the top face of the fireplace opening. Notch/close the damper and watch for a hint of smoke trying to roll out. Now open damper 1 notch. Now its balanced and tuned to the basic fire. This maximizes the heat reflected out and at its peak of efficiently. AS the fire dies down re set damper ect.
Inserts are not deigned well or serviced properly or burned properly. . A fireplace has a damper and smoke shelf 4"below damper in back and a throat to flue. The flue is designed not to be bigger then 10x the opening of the fireplace. Now we stick insert in and little opening in insert to a big cavern(throat) and the gases just slowly roll around and deposit large amounts of soot/creosote. This tars up and becomes a fire hazard. There only three ways to help avoid that. Once a week burn the insert wide open and really HOT to crystallize the tar and make it become inert. pull the stove out yearly and clean throat and smoke shelf. Or DRASTIC rip off face of fireplace, build down from upper flue eliminate throat and bring new flue closer to insert opening when its installed. A "heatalater" Is a pre formed steel fireplace with vents and blowers Its basically a insert destined properly and brick built around it.
My qualifications: First fireplace I built 1976 Mason since then self employed mason G.C. contractor 1979 and still working.
Hope this helps.
I bumped into this site. I just joined askmehelpdesk site and somehow bumped into this site.
So there the skinny on fireplaces vs inserts
Happy Holidays!
Signed 21 Boat
 

Last edited by 21boat; 12-24-08 at 04:49 PM.
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Old 12-26-08, 05:17 AM
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Thanks for that explaination - sure makes me want to avoid an insert now. I guess we'll try using the damper as you say. I always leave it wide open because we don't like to get smoke in the house.

One more question. Are we losing more heat up the chimney than the fire puts out into the room, with our front doors open all the time? It does not seem like it to me. It always seems much warmer in our room with a fire but maybe this is just how it feels.
I see those air tight glass doors for sale at around $750. Is that a good investment? It seems with those then the only heat from the fire would come from the 2 upper vents.
 
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Old 12-29-08, 05:30 PM
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Sorry 21boat, I have to disagree with you about fireplaces vs inserts.


Fireplaces were the latest technology in about the 12th century, but they are obsolete as a heating technology these days compared with a modern insert, and even more so compared to a modern wood stove. Hard to beat for plain esthetics, though.

The problem with fireplaces is two fold. 1) It sucks excessive amounts of heated room air up the chimney, and every cubic foot of that air is replaced by a cubic foot of cold air infiltrating the building 2) the hot combustion gasses tend to zip up into the chimney before they've had a chance to give up much of the heat produced 3) modern stoves and inserts do a much better job of burning up smoke, which is fuel that is largely wasted in a conventional fireplace.

A modern woodstove or insert greatly reduces the amount of air taken from inside the building compared with a typical fireplace. The air taken is little more than is really needed for combustion, while fireplaces usually take a lot more than is needed, even given your fine tuning of the damper that you describe.

And secondly, the insert or woodstove holds the hot combustiuon gasses in the stove long enough to extract a good portion of the heat produced, rather than having it go right up the chimney, with most heat produced limited to radiant heat.
 
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Old 12-30-08, 09:18 AM
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Sorry to bump in on this topic but my question may help. I have seen those fireplace relectors that are suppose to reflect the heat back into the room. They are stainless steel and polished to a mirror finish. Do these work. I see them on ebay for around $40 - $100 depending on the size. If they work then it would be money well spent.
 
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Old 12-31-08, 05:28 AM
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SeattlePioneer wrote:
"The problem with fireplaces is two fold. 1) It sucks excessive amounts of heated room air up the chimney, and every cubic foot of that air is replaced by a cubic foot of cold air infiltrating the building 2) the hot combustion gasses tend to zip up into the chimney before they've had a chance to give up much of the heat produced"

So,


Can someone tell me why the room feels hotter and the temp on our thermostat raises if the fireplace is sucking up room air?
I can undestand that most of the heat from the wood burning is going up the chimney, but I don't understand why the room becomes warmer if the theory is that the fire is sucking room air up the chimney. It sure seems like the fire is putting out some heat into the room.
 
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Old 12-31-08, 08:27 PM
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Originally Posted by tomfmal View Post

Can someone tell me why the room feels hotter and the temp on our thermostat raises if the fireplace is sucking up room air?
I can undestand that most of the heat from the wood burning is going up the chimney, but I don't understand why the room becomes warmer if the theory is that the fire is sucking room air up the chimney. It sure seems like the fire is putting out some heat into the room.

Often enough you'll find that the room where the fireplace is located is warm, but most of the other rooms in the house are cold, because that's where most of the cold air is entering.

Also, often the fireplace that's burning is in the same room as the thermostat. If you keep a big enough fire going to heat that room, the thermostat shuts off and there is then no heat going to the rest of the house --- which contributes to the rest of the house getting cold.

Also, if you build a fire big enough to keep a room warm, that's probably a LOT of BTUs per hour of heat that's being produced to keep one room warm. A furnace may have a BTU input lower than that of the fireplace, keep the whole house warm and only have the burner operating a part of each hour.
 
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Old 12-31-08, 08:32 PM
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Originally Posted by waterdowg View Post
Sorry to bump in on this topic but my question may help. I have seen those fireplace relectors that are suppose to reflect the heat back into the room. They are stainless steel and polished to a mirror finish. Do these work. I see them on ebay for around $40 - $100 depending on the size. If they work then it would be money well spent.
There are a variety of devices designed to increase the generally very poor efficiency of a conventional wood fireplace. The kind of reflector you described is one of many, perhaps the most common variety are pipes through the fire and coals that aim to exhaust hot air into the room.

These may improve efficiencies slightly, but they can't do a lot to overcome the basic flaws of a regular wood fireplace.

If you want a wood heating appliance, get a good woodstove or fireplace insert.
 
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Old 01-23-09, 12:59 PM
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I want to add to the comments about wood inserts compared to regular (open) wood fireplaces...


Today's fireplace inserts are more effiecient. The burns times are greatly increased and the most inserts have what is called "Secondary Burn". This takes place when the damper of the insert is mostly closed during a hot fire. Fire will be evident above the firebox thru Secondary Burn Tubes. This process burns smoke that will usually produce soot in your chimney. Making your insert more effiecienty by being literally smoke free..

Once load of wood in my wood insert burns for 7-8 hours.
 
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Old 11-07-10, 06:59 PM
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Personally designed wood burning insert with secondary/enhanced compustion

I just completed building a wood stove/fireplace insert for my home. I experimented with secondary combustion in my fireplace before I built the insert and was impressed and fastinated with the result. However, because the result was a much hotter fire, and my fireplace was very old and not solid enough to give me confidence in its safety, I stopped using the fireplace and started designing a heavy steel fireplace insert. To make a longer story shorter, after almost two years of thinking, designing, and building, I now have an insert that heats my house. The flames coming from logs looks like I have added gas or fuel oil to the fire, and there is no smoke coming from the chimney. Anyone else have experience with this?
 
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Old 11-21-10, 05:39 PM
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Personally designed wood burning insert with secondary/enhanced combustion

Originally Posted by TellGRBill View Post
I just completed building a wood stove/fireplace insert for my home. I experimented with secondary combustion in my fireplace before I built the insert and was impressed and fascinated with the result. However, because the result was a much hotter fire, and my fireplace was very old and not solid enough to give me confidence in its safety, I stopped using the fireplace and started designing a heavy steel fireplace insert. To make a longer story shorter, after almost two years of thinking, designing, and building, I now have an insert that heats my house. The flames coming from logs looks like I have added gas or fuel oil to the fire, and there is no smoke coming from the chimney. Anyone else have experience with this?
I would like to add some additional information to my post above:
For the past couple of years I have wanted to convert my fireplace into a secondary combustion fireplace / wood burner. This past year I saw a DESA fireplace insert that was offered at a very reduced price at a building supply store. After buying the fireplace insert, I used it as the foundation/pattern/shell for building my envisioned secondary combustion wood burner. Now I have a fireplace insert that burns wood without any smoke coming from the chimney and enough heat to warm my entire house. The result looks like the DESA fireplace insert but has a heavy enough core to handle the greatly increased heat produced by the secondary combustion. I used a heavier door assembly that is nearly air tight that I had used with my fireplace before getting the DESA insert. I don't know the model of the DESA insert that I used, but the dimensions are 48" wide by 40" tall, and it had folding glass doors and a sliding screen. It produces so much heat that I had to install a steel plate shelf above the fireplace, under the mantle and install small fans on the top of the mantle to send the heat into our living room.
An explanation of secondary combustion can be seen on this web site: YouTube - Advanced Woodstove Technology

1. This fireplace insert/wood stove produces so much heat in our 24' x 14' living room, that we have installed a "wall-to-wall" fan in the wall near the ceiling between our living room and our dining room to carry the heat into the rest of our house and reduce the intensity of the heat in the living room. 2. The insert is insulated on three sides, over the top, and around the chimney pipe's first five feet above the firebox with several inches of insulation that is used in ovens. This special insulation is a pretty solid material that can be shaped into blocks and layers to be fit and pushed where needed. 3. We have the first five feet of chimney liner above the fire box made of 3/16" thick, 8.5" diameter steel pipe, and the rest of the chimney above it has been rebuilt in the past five years. 4. To move the heat out into the room we have four small 4" diameter fans mounted on the top of the fireplace mantle. 5. To help circulate the air around the firebox we have four small 4" diameter fans mounted in front, under the firebox. 6. To inject air into the space above the normal flame helping to ignite the heated, normally unburned gases, we have used 3/4" black pipe, purchased from a hardware store. We ran four pipes through the four knock-out spots in the brick inserts on both sides of the firebox, up the insides of the firebox and across the firebox above the the glass doors line of sight of the fireplace insert. Each of these pipes has 1/4 inch holes drilled in them about 2" apart to allow heated air from the space around the firebox into the upper, inside of the firebox
 
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Old 11-21-10, 06:19 PM
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Wood stoves are a leading cause of fires in homes, and insurance companies might wind up refusing to cover a fire in your home caused by an unregistered or uninspected stove.

Did you pull a permit on your stove installation and have it inspected? Have you informed your fire insurance company that you have a stove you designed yourself in your home?

If you've done these things I'd suppose it would be hard for an insurance company to wiggle out of a claim. If you haven't, you may be taking a chance that they will.
 
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Old 11-23-10, 05:47 PM
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Thanks for the advice. It's good for me and anyone else reading these descriptions.

I'm still learning. Yesterday, when cleaning the firebox on our fireplace insert / wood stove, I noticed that with the fire being so hot, the "brick" liner was being affected. There were some hairline cracks and the color was changing slightly in some areas of the "brick" liner. Therefore I installed a 1/4" thick steel plate across the back of the firebox, over the brick liner where these changes were seen, and on top of the brick liner on the bottom of the firebox.
 
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Old 12-07-10, 02:43 PM
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Still learning.....
I installed a "damper" in the top of the firebox where the chimney pipe starts. It's a flap/door that is controlled with a handle on the front of the (fireplace-insert-wood stove). I have learned that, after a few minutes of initial fire with the "damper" wide open, heating the firebox and chimney, I can nearly close the damper and get a more controlled fire with flames that are very long and thin. This still does not produce any smoke and extends the amount of time that the fuel/wood lasts, and gives plenty of heat.
 
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Old 12-08-10, 05:55 AM
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Post Re: Conversion of fireplace insert to secondary combustion


MACMS wrote:
What is the typical amount of time you can burn 1 load of wood, meaning the amount that you put in the stove at one time?




I'm not sure that I can answer your question in a way that will satisfy your interest. Since we use this insert/wood stove/fireplace as an additional heat source and as a decoration/entertainment, we don't load the firebox for a long term fire. We put several logs into the firebox that will provide a beautiful fire while we watch television, read, and/or eat a meal together in the living room. Also, we have been burning a mixture of types of wood: elm, maple, oak, popular, etc. We go to bed at about 10pm (we don't load the firebox again) and when I get up at 2am, ( for a short break ) the shell of the wood stove is still warm, but there is no flame and there are no live coals visible.
 
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Old 12-15-10, 11:00 AM
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It has been pretty cold for the past week. I have found that my new converted fireplace insert has done a great job heating my house during this time during the day. I'm sure glad that I installed a room-to-room, in-wall fan to move the heat from the living room into the rest of the house.
I have learned that if I re-load the firebox with wood, before fire burns down to coals and the unit cools off, when the re-loaded firebox gets burning again, the unit gets hotter than I am comfortable with.
 
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Old 01-19-11, 02:28 PM
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Personally designed wood burning insert with secondary/enhanced combustion

1-19-11 Update:
I have just replaced the 1/4" thick steel plate that I had installed over the 1 1/2" thick brick liner in the back of the fire box. I thought that after welding (2) 1/4" thick X 1 1/2 " straps horizontally across the plate it would make it less susceptible to warping. Well...the straps helped but the intense heat still warped the plate. In fact it developed a bulge about 6" from the bottom of the plate. Therefore, today I replaced the plate with another one, but now I welded seven straps horizontally across the plate spaced so that I could place eight cast iron window weights across the back of the fire box to take the intense heat. These window weights are about eighteen inches long and about 1 1/2" in diameter. I welded the straps to have a 60 degree slope (front to back), allowing the cast iron weights to be just laid on the straps. This afternoon, when I added wood, I saw that the top cast iron weight was red hot.
I'm still very happy with how this fireplace/wood stove/insert is working.
I have photos of the construction process and "final" result.
 
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Old 01-21-11, 10:04 AM
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Unfortunately, this thread is a case study in why making your own heating appliances is probably a mistake.
 
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Old 01-27-11, 06:10 PM
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It's been a week now, and the addition of the cast iron window weights have done the trick. The steel plate at the back of the firebox with cast iron weights laying on the narrow "shelves" has protected the steel plate from changing shape at all. AND the cast iron holds the heat to help reignite the new wood that is added to the firebox when it has only coals left.
 
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Old 01-27-11, 07:52 PM
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Originally Posted by SeattlePioneer View Post
Unfortunately, this thread is a case study in why making your own heating appliances is probably a mistake.
I heartily agree. Based on some of the "corrective actions" that he described, I'm surprised the last entry from TellGRBill wasn't about how long it took the fire department to respond.
 
 

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