smoke comes in from chimney

[123mtl]

Hello
as you can see in photo, when A (Ground floor) is on the smoke comes in from B (Basement).
in the picture i put cap on B, but i like to use both fireplace and stove in winter.
what's the solution?
Thank you

 

[vbu]

I'm sure the experts will chime in, but I believe you need a height difference between the 2 flues to prevent this from happening

 

[stoveliker]

Yes, (not an expert, but) make one of them larger, 1 ft to 18" or so, than the other.
I would also add a weather cap on B if you are going to use it (like on A).

This can happen when there is a "chimney effect" in your home - as in air from the basement is warming up and going up in the home and escaping at the top. Air sealing your attic, so that no air from the home escapes there, will also help - as well as with heating bills.

One remark: fireplaces are great for fireview, atmosphere, cozy (as someone else here said: no one wants to hug a radiator). But the fireplace may also cost you more in heating cost. First, when you use it, a LOT of air goes up the chimney. That needs to be resupplied, and will thus leak in elsewhere (e.g. the stove in the basement..., but also doors and windows etc.) That cold air will be cooling down your home in the rooms where the fireplace is not heating things up. If your thermostat is those rooms, you may actually burn more gas or whatever you use for your central heating system with the fireplace on.
Also when the fireplace is not in use (in winter), warm air goes out the chimney, even with the damper closed - they are not air tight.

So, if the remark "in winter" means you want to heat with it, you could consider putting in an insert. Modern ones have big windows, so fireview is still there. They are way more efficient. (I'm assuming this is a proper masonry fireplace as it looks to me.)

ANyway, that's my 2 cents. I understand the choice for a fireplace - it's the same reason I have fires outside in summer. But it's not good for heating (bills).

 

[begreen]

Raise the fireplace chimney A by 12-18" to stop the siphoning of smoke into chimney B. It will need a brace added at the 5ft point above the roof. Is the fireplace a zero clearance fireplace? If so, that will limit or prohibit insert options. The chimney looks kind of black which indicates either poor wood or the fire is not getting hot enough for full combustion, or both.

Also, get a cap on the open basement chimney. Water should not be going down there and may cause other issues.