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I have a propane fire pit in the center of a table on our patio. Since the weather is still fairly chilly where we are, I was trying to think of something creative to channel the heat towards the 4 seats on each side of the square table rather than straight up in the air. Does anyone have any ideas? Thanks in advance.

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  • If you could add some sort of picture that would help. I'm having difficulty visualizing what "a fire pit in the center of a table" really looks like.
    – FreeMan
    Mar 27 '20 at 15:29
  • Just added a link Mar 27 '20 at 15:31
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    Ah! Totally different than what I had envisioned.
    – FreeMan
    Mar 27 '20 at 15:35
  • There's a lot of free info out there to help you understand the basic physics of heat transfer. Bottom line is that to warm your guests more, they need more line-of-sight exposure to the fire (or stuff heated by the fire)... so you need a bigger fire. khanacademy.org/science/physics/thermodynamics/… Mar 27 '20 at 15:59
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    The fundamental problem is that this fire pit is not designed for warming anyone. It's ornamental and probably will get pissed at you if you so much as roast wieners over it. Mar 27 '20 at 17:32
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Reflection of radiant heat is what you would be after. If you could magically hang it, one of the best would be a metal surface above the fire reflecting heat back down to everyone. Using an upside down cone or pyramid shape, with the middle point centered over the burner and the angles set so that the surfaces would reflect the fire and heat (radiant heat and the light of the fire follow the same path) right at the seating area. A hanging flat surface would go a long way too, such as a hung metal plate or even a tarp (don't start a fire). I'm not sure that this is that feasible. I don't think much else would help since the heat is mostly radiant and any that is in the form of hot air will just rise away if not in some sort of enclosed structure

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  • And you'd want to be careful not to deflect the fumes back at them+
    – JACK
    Mar 27 '20 at 2:10
  • So I'm able to use a dial to dictate how large the flames are. My goal is to have it in low flames but redirect the heat to the 4 chairs in each side if the table before it goes up in the air. Mar 27 '20 at 15:33
  • I had approached the solution to keep the fire pretty. If you were to be ok with it not remaining the same, you could put the metal surface very close to the fire and use a different shape. For example, an old stew pot on a grill grate over the fire. The grill holds the pot close and still allows the fire to go around, and the fire to get air, then when the pot heats up, it radiates the heat off the vertical edges right at you and your guests. The taller the pan the better (a stove pipe?). The hotter you let it get, the better. Red = lots of heat coming at you
    – Ack
    Mar 27 '20 at 17:44
  • Oh, I just saw the picture you added and not what I was thinking. It'll be tough to get much heat off of that, it's simply not there in the first place. But to get what heat you can, you can try a metal bowl or any oven safe item with the idea that the vertical surfaces get hot and redirect the heat at you. Probably best to keep your expectations on the lower end
    – Ack
    Mar 27 '20 at 17:49
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Ack's idea is reasonable, but I don't think you'll see the outcome you're after even with an ideally designed reflector. This type of table works by heating up and then radiating heat energy outward. Radiation dissipates with the square of the distance, meaning that an object at 2 feet from the heat source gets 1/4 of the heat that it would at 1 foot. At 3 feet, that drops to 1/9 (1/3^2). So...

  • Let the table heat up for a while in advance. All the rock and the containing metal should be hot before your guests arrive.
  • Situate them close. Chairs need to be up to the table.
  • Don't expect miracles. This isn't a bonfire.

You might look at suspending the cover over the fire, say about 10 inches up. This would force heat to remain in the vicinity longer and keep things hotter. It would also collect and radiate heat itself. You could bend up some rebar legs that sit just outside the pit.

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I was thinking of putting an artful (perhaps shaped like a swirling ship or something appearing reaching up) light weight steel wind turbine that would be turned by the air rising by heat of the fire which would turn a gentle fan under the table directed at the underside center of the table with heat exchanger fins, which would bounce the air out toward the legs of the people around the table. High quality bearings for the turning rod under the table would be needed. I live in the desert, so have not been motivated enough to push it above other projects I have in mind.

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