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Hi Guys,
I was visiting a friend last night who has a shallow fireplace in an old house that they would like to use for open wood fires. The fireplace seems like it must have been used with a stove – it seems small for an open fire. Anyway, it was pretty windy outside and periodically, the flu stopped drawing and the house would fill with smoke. The fireplace was recently used uccessfully, but in non-windy conditions. The chimney was recently cleaned and deemed safe.
1) can this sort of fireplace be used for open fires?
2) is it normal that the flu would not draw if there was a strong wind? Why?
3) what can be done to keep the flu working in a strong wind?
Thanks for your help.
Kim Carleton Graves
Carleton Woodworking
Replies
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Kim,
I've been working with a very experienced mason on a recent project and had a long discussion with him about fireplace draw problems. In short, there are many, many factors that affect the draw of a chimney, such as:
the size of the flue
the ratio of the size of the firebox to the size of the flue
the depth of the smokeshelf
the taper of the throat
the height of the stack
exterior wind patterns
the pressure dynamics of the house as a whole
other factors I'm sure I've forgotten about
You need to get someone in there who knows their stuff to take a hard look at it.
Steve
*Kim: Steve is right there are many factors, but to simplify it a bit: A chimney can be too large in diameter (the hot air get 'lost' and doesn't produce enough draft), too small in diameter (too much frictional drag from too small a pipe) and can be too short. A ch imney can not be too tall. Too short is definitely most common, especially in one story houses. If you have problems on windy days only, then likely downdraft off the peak of the roof is reducing the chimney's draft too much. Ideally the chimney comes a few feet above the peak of the roof. If not there's a guideline of 1 feet below being allowable for every 4(?) feet to the side. Something like that. Try mounting 3 to 4 feet of flue pipe onto the top of the chimney, it will probably help a lot. If so, then decide whether you want the permanent solution to be brick or stainless or galvinized.I was once in a rental house with the same problem, didn't want to spend my time and money on it and could get by on windy days by taping aluminum foil across the top of the fireplace opening, lowering it by 4 inches. That was enough to keep the smoke going up the flue instead of into the room.Too small could develop if the chimney has lots of soot, creasote, bird's nests or dead squirrels in it. Creasote is less likely in a fireplace (oxygen rich) than in a wood stove (starved for air). But $100 to a chimney sweep can give a lot of peace of mind. Chimney fires are way more excitment than you want on a cold winter night - I know!The shallow depth of the fireplace may be good design. A "Rumford" fireplace (there was a FHB article about 1-2 years ago) reflects heat into the room because of its shallow depth and because it tapers towards the back. Stay warm,David Thomas, Kenai, Alaska where it's warmed up 25 degrees in the last 2 days. It's now 0 degrees F.
*KimThe chimney ratio that Dave refers to is: chimney must extend 2 feet min. above anything within 10 feet horizontally. That "thing" being the roof pich, or a side wall. So visualize a triangle made of the chimney, the roof and the horizontal line between the chimny and the roof, and see where a horizontal line 10 feet over comes on the chimney.If the draw is reduced due to wind, try cracking a window or door.-pm
*For a ton of info on Rumford fireplaces go to: http://www.rumford.comJerry
*Kim, It is time to get a serious professional in there. A shallow fireplace in an old house is probably a coal burner. It is not suitable for wood. Tapinging a piece of aluminum over it may start a fire or burn the hell out of anyone who touches it (A child perhaps). Do not trust a chimney sweep. A real pro will have a special camera that cah go up the chimney. The old fireplaces do not have flue liners. Any cracks can become house fires. Check if you have a local Ahrens rep. It can cost a lot to get a fireplace working properly. but the cost is a lot less than waking up with your bed on fire, or seeing your child die! If you are not going to get it working properly, do not use it!!Rick Tuk
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What should be done about the cracks appearing in a new
5 month old) Majestic fireplace-in the ceramic (?) insert? What is the best type of chimmney cap for this type of fireplace? Any help will be appreciated.
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Hi Guys,
I was visiting a friend last night who has a shallow fireplace in an old house that they would like to use for open wood fires. The fireplace seems like it must have been used with a stove - it seems small for an open fire. Anyway, it was pretty windy outside and periodically, the flu stopped drawing and the house would fill with smoke. The fireplace was recently used uccessfully, but in non-windy conditions. The chimney was recently cleaned and deemed safe.
1) can this sort of fireplace be used for open fires?
2) is it normal that the flu would not draw if there was a strong wind? Why?
3) what can be done to keep the flu working in a strong wind?
Thanks for your help.
Kim Carleton Graves
Carleton Woodworking