Neo 2.5 Fan Blowing Smoke

[Johnnyhighhips]

I have a 2 flue chimney. In the upstairs fireplace I have a Neo 2.5 insert. Everything works great. 2 weeks ago for the first time I lit a fire in the fireplace in the basement. Everything seemed fine, but when I came upstairs my Neo was blowing smoke out of the fan exhaust. I have never had this issue before I lit the fire in the basement fireplace.

The Neo is connected to a 6" liner that runs the length of the chimney with a cap on it. What could cause this. As long as there is no fire in the basement everything works like it should. I have not had any issues in the past. Could it be pulling smoke from the other chimney flue? Do I need to just extend the liner on the upstairs flue? Where does the Neo draw air into the blower? Any help would be appreciated. Thanks!

 

[begreen]

Do both chimneys terminate at the same height? If yes, one can be pulling from another. Adjacent flues should have a height difference of 6-12" so that one doesn't siphon smoke from the other.
https://extendaflue.com/faqs/

 

[Johnnyhighhips]

Thanks begreen for the quick response. Yes, both are the same height. I thought that could be an issue from reading other post. I saw the extender chimney caps. Has anyone used those in the past? That seems like the easiest solution. Also, it seemed like the fire was struggling for fresh air in the Neo when the downstairs fire was going.

 

[begreen]

Could be multiple issues happening here. If the house is pretty tight then negative pressure may be extending to the first floor when there is strong air consumption (and exhaust via chimney draft) occurring like when the fireplace going in the basement.

 

[Johnnyhighhips]

So...I extended the upstairs flue by 12 inches this morning. Stoked the upstairs insert and had a nice fire going and the fan blowing. I then started a fire in the basement fireplace. Went back to check the upstairs fire and immediately noticed smoke being blown out by the fan. Not sure what could be the issue now?? Could I have crack in the basement flu and my Neo is pulling smoke from that?