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.
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
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.
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.