Our house has a large double sided fireplace right in the middle of it. It has a vent above the doors on either side to circulate the hot air, which is not all that effective. I wondered if it would help to have air forced across the firebox and decided to try an experiment. I rigged up a window fan to blow air into the vent in one room.
It actually does help. It makes the living room, on the other side, nice and toasty.
…used to be masonry fireplaces were a thing: once that thermal mass heated up, it would radiate for DAYS…
The average fireplace is probably only about 10 - 15% efficient. That’s before you factor in the impact of the draft on the conditioned air space in your home. Ours fireplace draws extremely well. If we ran it with the doors open it would suck the air out of the house faster than it could heat it. Fortunately it has a fresh air intake from outside but which helps minimize the air drawn from the living space.
I’d imagine even with those the majority of the heat still just shoots out the top. There needs to be something that captures the heat/cools the air and dumps it back into the house. Sort of similar in concept to a condensing natural gas furnace (apart from the bit about converting it to water, just that it captures more heat).
https://www.hvac.com/expert-advice/what-is-a-condensing-furnace/
These days we just stay cold because electricity is too expensive.
Our parents were so fucking smart to decide hearths should be obsolete.
…builders cut construction costs; modernist fashion aside, buyers weren’t crying out for cheap sheet-steel fireboxes…