any fireplace/chimney experts

I have a house that has a walkout basement. There is a woodburner downstairs with a woodburner directly above on the 1st floor. both burners are hooked into the outside brick chimney by stove pipe. both stoves have the same basic pipe attachments to the brick chimney(3ft of pipe with two 45 bends in them). I have tried to figure it out but for some reason I cant get a good draw on the upstairs woodburner.anytime the doors open the smoke stops going up the chimney and floods the house with smoke. somebody told me since the basement it not heated all the time that the cold air downstairs pressure is differnt from the warm air in the chimney or upstairs and will cause the column of hot air to collapse onto itself causing the flood of smoke when I open the doors. Is there any truth to this or does anybody have any other idea's? could it just be the design of the wood burner? am I not getting the chimney hot enough? I am trying to cut down on the wood smell but fear it is gonna be the nature of the beast.

Can you close the doors on the downstairs burner or does it have a way close the pipe off? I think I can see what is happening but I'm not sure I could explain it well. I think you need to be able to block off cold air from below coming up and hitting the hot air upstairs as I think it's cooling the hot smoky air enough that it essentially crashes down and out into the room. Only hot air rises and that may create a vacuum pulling up the cold air from below as that may be the path of least resistance to pull from. When it hits the hot air it stops going up and just sloshes out wherever it can. That's just my guess of what's happening anyway.

You might want to look at section III B on page 11.

Woodstove info.

This is a pdf file from Maine.gov. Multiple wood stoves with a common flue are not recommended for several reasons.

I wonder if double metal flue pipes inside the existing chimney would solve the problem, if they would fit. My old house had a similar arrangement, but it was designed that way. In that case, it had separate flues boxed in a wooden chimney.

Geoff

You should have two separate flues - one for each stove. If you don't, you shouldn't be using this setup.

If you do have two flues, the upstairs doesn't happen to be a fireplace that has been closed off?

What's the pitch of the roof, where is the chimney located, how high does the chimney extend above the peak of the roof and how far away is the chimney from the peak of the roof?

What size is the flue, what size is the stovepipe and has the stovepipe been changed from the size that is was made for (does it use a reducer or increaser)?

If you don't have one of the above problems, the likely problem is a combination. The length of chimney is not as tall, so it doesn't draft as well as the longer run downstairs and the chimney is cooled by the presence of the adjacent downstairs flue. Depending on the height and location of the chimney, you could have winds hitting the peak of your roof from the opposite side creating down drafts.

The easiest fix to try is to burn the stove hot long enough to get the flue warmed up. Once the flue is warm, your draft should increase significantly.

As soon as I get a chance I will post pics of the set up. The chimney does have three seperate runs and each stove has its own flue. The chimney is at one end of the house in the corner. It also extends a few feet above the roof. The weird thing is is there is a point where the doors are at when I get a good draw. like almost closed all the way. but if they are closed all the way the fire will die.

A third flue? That might add to further cooling the flue for the upstairs stove depending on placement.

With the doors partially open, is that when you are starting a fire or when you have a good hot fire with a nice bed of coals?

Need a lot more info to make an intelligent assessment.