All the heat goes up the chimney myth

[SpaceBus]

On the other hand, indeed not *all* the heat goes up thru the chimney. At least a small fraction stays in the home when it's burning. So I have to adi that the title is not wrong.

Unfortunately, homes with fireplaces loose that much heat during burning and when not burning (! The latter are the majority of the hours in a year..), that homes with fireplaces use more energy to be heated than homes without fireplaces. See that (peer reviewed) article I mentioned a while back.

The losing heat after the fire goes out is important, but the title is literally correct, even if that doesn't count for anything.

 

[stoveliker]

The losing heat after the fire goes out is important, but the title is literally correct, even if that doesn't count for anything.

That is what I tried to say. Maybe not well, but I tried.

 

[Ctwoodtick]

A number of years ago, we had a power outage for a couple days. This was before having the wood insert , so only an open fireplace. The den where it’s in stayed reasonable warm, maybe low 60’s . Rest of house chilly. We also ran out of firewood that night. Woke up to 40 degrees in the house. 8 degrees outside temp. Not fun.

 

[ctyankee]

metallica give me fuel - Google Search

www.google.com

 

[ctyankee]

 

[wjohn]

Not exactly apples to apples, but to illustrate the OAK thing... I had an FMI 3600 prefab ZC fireplace in my house when I moved in, with a 4" outside air duct directly into the side of it. It was a 2' run out to the side of the house from the fireplace, max. Before I did any work on the house, I could never detect any airflow in at the intake on the outside of the house (testing with something very thin and light, like receipt paper). I could, however, tell when I had the fireplace going because I could put my fingers near the old windows, attic door, etc. and feel all the cold air being sucked in. You could barely keep the house at 60... Some days only 57 or 58.

I redid the house, adding housewrap, new windows, and did a ton of air sealing with the exception of the attic door, where I just taped a bunch of foam backer rod into the gaps. Same experience - no detectable flow into the OAK intake. With 8" chimney there should've been a ton of air going in through there. You could about freeze your fingers next to any little crack I couldn't even see in my taped in foam backer rod around the attic door. It was still sucking in air that way. Mind you the attic access is at the very far end of the house from the fireplace.

If the house had been 100% sealed airtight everywhere, then maybe the OAK could've been the only possible source of air? Thing is that's almost impossible even with fantastic new construction sealing practices. I think the whole house was at slight negative pressure because the 4" OAK was like a straw. Air just got sucked in anywhere and everywhere there was a tiny crack or pinhole.

Tore all that out, installed a stove, and used the OAK at first. No more sucking air in around the attic door and my receipt paper would just hold itself to the inlet of the OAK from the airflow. Disconnected the OAK, and still no cold air being pulled in past the attic door (at least not that I could detect with my fingers). The amount of air getting sucked in through the maybe dime sized combination of the secondary and primary air inlet holes is almost nothing.

 

[john26]

I was wondering about an OAK thing. How much air would have to be piped in to the fireplace, from a window (or wall) for ex. I'm thinking of a tube? Would it have to be huge in diameter? Any thoughts would be interesting. Thanks

When I first moved in my current house I had a few fires in a 2'x3' masonry fireplace that had a 4"x6" vent in the bottom that opened so I opened it. I did have radiant heat directly in front of the fire all seasoned red oak, but back on the couch about 10' away it was cold. The rest of the house was cold, the NG furnace ran non stop, but it did help me find air under the entry doors.