Smoke coming down the chimney.

[dogtag1968]

:question: When I burn the upstairs fireplace, smoke goes down the basement fireplace. Both fireplaces use the same chimney and the flu's are about equal heights.

If I build a fire in the basement fireplace it will not vent out the chimney and fills the basement with smoke.

I had a chimney sweep check the fireplaces and chimney before I built the first fire this fall and was told that no problems were detected.

TIA for any and all thoughts and ideas.

 

[n3pro]

From what I know the problem is two fireplaces with the same chimney. I didn't think that was legal! The smoke follows the draft, and draft is your basement. I'm surprised the chimney sweep didn't say something.

After rereading the post I am confused at what you are calling a flue and what are you calling the chimney.

 

[burntime]

Can't have 2 fireplaces in 1 chimney is what I thought as well. If there is any negative presure you will be backpuffing.

 

[Girl]

Are there 2 separate flues for this one chimney?

 

[dogtag1968]

Thank you for your replies.

The fireplaces were built one above the other with each having thier own seperate flues,sharing the same chimney encasement.

Apon reading a search I found in this forum it appears that the flues should be from 4" to 12" differance in height. As mine are about equall height to eachother.

So I guess my next question is, is this a job that a person with little masonry skills should try on his own. I ncan buy the flu extension and some premix masons mud at Home Depot.

 

[snowtime]

What i would do is get some regular cheap single wall stove pipe and extend one of the pipes to see if it works. If it does than you can decide on whether you want to tackle the job yourself. This way if it does not work you could transfer the new pipe to the other chimney to see if thats the one needing extension.

 

[humpin iron]

You have negative pressure problems. Yes you can have two or twenty FP in the same chimney, they just need separate flues, think of it as one house with many bed rooms.

How old is the house? How tight construction? Try opening a window in the room of the FP that you are lighting, sounds like outside air would help relieve some pressure.

If the house has tight construction something as simple as a bathroom fan can cause the chimney to back draft

 

[woodheat]

We live in a raised ranch and had the same issue as you did. the first night after purchasing the house and being first time home buyers, we popped a cork lit a fire and some candles, etc. after 20 minutes or so it was getting noticeable that something smelled smokey. We went downstairs to find the whole lower level filled with smoke. We quickly opened all the windows down there to air it out and the smoke started to dissipate. After that we figured out that as long as we left a window open down in the lower level it did not do it anymore, talk about bad efficiency of a fireplace. The next summer I rebuilt the top of the chimney and made 1 flue a foot higher than the other. That stopped the problem.

After realizing how useless a fire was in the fireplace for producing heat, we ended up putting a Jotul Rockland insert in the lower level last Feb.. After doing some modifications with fans to get warm air to go upstairs, once you get it going for a couple hours it heats the whole 1800 sq. ft. house.

 

[dogtag1968]

thanks guys, your replies make perfect sense. i will try your suggestion's and get back with the results and remedy asap.


once again, thanks

 

[stanleyjohn]

When i used the first floor fireplace before i had the wood insert put in i also had a problem with some smoke in the basement.The smoke would go out the fireplace flue and some would exit down the oil burner flue.One day when i had the oil burner man serviceing the burner i ask him about it and he said it was because todays homes are sealed real tight!Just crack open a window and no more smoke in cellar!It worked.

 

[oconnor]

Do a search here for stack effect, and you will get an overview of what is going on with your flues/house. That is were the reference to negative pressure problems is coming from. Your basement fireplace probably downdrafts all the time, bringing cold air into your house - you just notice it when it brings in smoke too.

Fireplaces aren't very efficient anyways (many are actually negative efficient, as they lose more heat over a day than they create when a fire is going). If you are looking to heat your house better, you might consider an insert in both or insert in one and block off the other - the cost of the insert would likey be repaid in heating costs in short order.

Otherwise, you can buy inflatable flue blocking "balloons" that prevent drafting/backdrafting when fireplaces aren't in use - cheaper if you only use the fireplace for the occasional ambience opportunity. Never heard much feedback on if they are worth it, but have seen them for sale online.

 

[Chettt]

The previous owner of our home extended one flue/cap several feet above the other one. The lower one is used for our woodstove and the taller one is largely unused. If it is a rainy/low pressure day and I run the clothes drier I can sometimes smell some smoke backdrafting in the unused flue. Not knowing your situation completely I would suggest making one significantly taller than the other.