Poor Circulation?


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Old 01-02-10, 04:01 PM
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Poor Circulation?

I have a wood burning fireplace (no insert) and think I have a circulation problem. The fire doesn't burn very hot and often smolders. Wood is seasoned and dry, and I have even bought some logs from the store and they do not burn very well either. I think I may have an intake problem. There is a 3" x 6" intake opening on the bottom of the box towards the front, which I open all the way, but I don't feel much air coming in. I cleaned it out, so I know it is not blocked. Is this not enough of an opening. I figured having the intake open and the fireplace doors open would be sufficient, but evidently it is not. Is there an intake fan that I can install to supply the firebox with more air? Should I install an angled piece inside the intake channel so the air can flow more freely (currently a 90 elbow at the inlet to the firebox).
 
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Old 01-02-10, 04:39 PM
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Is this a masonry fireplace? How big is it and especially how big compared to the size of the fire you are attempting? You need a hot fireplace to burn well and if you are attempting a fairly small fire in a large fireplace you will almost always have problems.

Do you have any smoke problems? What are the dimensions of the opening? Pictures might help.
 
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Old 01-02-10, 05:16 PM
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Yes, it is a masonry fireplace and its about 18 cu. ft. (3'x3'x2').

No smoke problems, opening is about 30" x 24". Duraflame logs burn fine, but natural wood not so well. FYI, I can light a match with the intake and flu wide open and the match doesn't blow out. Also, if I wasn't clear, the intake leads to the outside of the house and is about 3 feet long.
 
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Old 01-02-10, 05:30 PM
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Is that 30 wide and 24 tall? Are you using a grate or andirons? How much ash under the grate or andirons? How tall is the chimney? Are you able to maybe hold something over the upper area of the opening (effectively making the opening less tall) to see if maybe you have too much room air going up the flue through the upper area of the opening? Just holding a piece of cardboard over the opening for a couple of minutes should give you an answer.

Have you tried keeping the glass doors shut to see if that helps? I'm kind of grasping at anything right now as fireplaces are not really my "thing" but I do know a fair bit about combustion and what it takes to burn fuels in an enclosed area.
 
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Old 01-02-10, 05:55 PM
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Opening is about 30" wide by 24" tall, chimney box (not sure if that is what it is called) is about 33" wide, 22" deep, and 36" tall. Chimney is about 20' tall. Every house on my street has the same setup. I will try closing the doors to see if that helps. If it does, do I have too much air flow, or is the area too large?
 
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Old 01-02-10, 06:04 PM
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If it burns okay with the doors shut then it means that the chimney draft is "pulling" the air from the room and it doesn't go under the fire where it needs to be to promote combustion. That's actually a good thing because it means the fireplace was made to burn with the doors shut and you should only open the doors to add more wood or occasionally poke the fire.
 
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Old 01-02-10, 06:15 PM
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Forgot to mention, I am using a grate and there are no ashes underneath. Doesn't seem to make a difference if there is or not.
 
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Old 01-02-10, 06:19 PM
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Hmmm. Interesting. Ok. But if the doors are closed, how am I going to get any heat in the house? Also, we use it primarily for the ambiance, so we like the doors open. Is there something else we can do to eliminate the excessive draft? (close intake, keep flu open to minimum setting?)
 
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Old 01-02-10, 08:30 PM
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Burning a Duraflame log as we speak, and it is burning like a champ with the glass doors closed. So apparently you were right, there was too much air being sucked in from the room and out the flu. Unfortunately, it doesn't put off much heat at all with the doors closed, but it looks nice, which is the main reason we burn fires to begin with, so that's ok. Guess if I want to heat the house, I will need to get an insert. Thanks for your help.
 
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Old 01-02-10, 11:45 PM
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An open fireplace is almost always a net loser when it comes to heating a house because more heat is lost up the chimney than ever escapes into the house itself. What little heat can be released to the house is mostly radiant heat and that will travel through the glass doors just fine while the doors keep the heated air of the house from escaping up the chimney.

Duraflame logs put out very little usable heat, they really are just to set the mood with your sweetie which really is all a fireplace is good for anyway. Also, a Duraflame will never get the masonry hot enough to really help in supporting combustion.

In my previous house I had a LARGE fireplace in the living room. It took a large fire to get any heat from it but if you kept a large fire in it for several hours the bricks would radiate heat back for at least a day after the fire went out. It did okay in heating the living room but it left the rest of the house bitterly cold so I seldom used it except to get rid of scrap wood. That's pretty much how I use the tiny fireplace in my present house too, getting rid of scrap wood.
 
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Old 01-03-10, 09:47 AM
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Good to know. Looks just fine with the doors closed. Burned a natural log on top of the Duraflame last night and it didn't burn very well, but I think it was a little wet. Think it will be fine though. Thanks for your help.
 
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Old 01-04-10, 07:49 AM
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Poor Circulation

May I make a suggestion here. I have run into problems like this before . Burning the Duraflame logs hasn't solved your problem. They're a manufactured product , using chemicals and will burn almost anywhere , not to mention the odor from them . You appear to have the ingredients of a good working fireplace . The fact that your dry wood only smolders with the doors open or closed tells me your not getting enough oxygen in the room . Take a look at an air tight stove . You close the air intakes and the wood smolders , you open them and the flames start up and increase . Homes today are lined in plastic and insulation keeping warm air in and the cold out therefore keeping out enough oxygen to supply your fire . The vent at the front of your firebox is your supply however it appears to be restricted in some way . A process of elimination , as an experiment , try opening a window at different levels to see what happens . If this works then you need to re check your oxygen supply and by the way I spent 8 yrs. with my wife and kids in a cabin up in the Canadian north country with just a wood burning fireplace and cook stove . They supplied us with warmth and cooking . The romantic ambiance was just an enjoyable byproduct
 
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Old 01-06-10, 04:27 PM
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Think I figured out the problem. The metal door that was originally mounted to the intake was removed by the previous owner when they installed a woodburning stove, which I removed when we bought the house. Therefore, the air entering through the intake is bypassing the logs altogether and traveling up the flu. When I take a brick and position it at a 45 degree angle, the fire begins to roar. Where can I get another one of these metal covers etc?
 
 

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