# fire pit heat shafts



## Jim F (Mar 4, 2010)

That's a first. There is a guy in the project section that built a nice stone veneer firepithttp://www.diychatroom.com/f49/stone-veneer-firepit-71777/ . I'm thinking your efforts would be better served to vent the walls of youf pit above ground in such a manner that the heat flows under your seats.


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## Bondo (Dec 8, 2007)

twrexx said:


> Hi all, nice to be here!
> 
> To get right to it, Im researching a fire pit design, and havent come across anything online about it. Here is the idea:
> 
> ...


Ayuh,... Heat Rises,... yer trenches won't do a thing for heating...


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## jburd964 (May 4, 2009)

If design did work it takes a lot of btu's to heat a pile of dirt. Pit would have to be lite way ahead of time for that, but you could be sure it would stay warm along time after you leave.

I'm not a professional., But I did stay at Holiday Inn Express last night.


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## BriBri (Dec 13, 2011)

You could try some kind of steam heating.

Create a water reservoir surrounding the firepit (perhaps enclosed in a water-tight pool between the firebrick and outer masonry). Run copper piping from the top of the 'reservoir' to underneath the seating surface (assuming it will be some kind of stone slab).

Alternatively, you could fabricate some kind of forced-hot-water arrangement operating on the same principle as above. You could get one of the boiler tanks used in houseold furnaces and embed that in one of the walls with direct exposure to the firepit flames.


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## twrexx (Dec 21, 2011)

Bondo--am considering the factor of the heat rising, but if the distance isn't too far, and perhaps the pipes at a slight incline toward the seat, I thought maybe it could work.*

Bribri---haven't considered the boiler, that's an interesting twist. I'm no engineer though. I'd have to be well researched before I started getting froggy like that haha.

Jim- ill have to take a look at that fire put you linked, I'm up for any options. This is a long term project, so no rush.


Thanks for all the input so far everyone.


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## Bondo (Dec 8, 2007)

twrexx said:


> *Bondo--am considering the factor of the heat rising, but if the distance isn't too far, and perhaps the pipes at a slight incline toward the seat, I thought maybe it could work.**
> 
> Bribri---haven't considered the boiler, that's an interesting twist. I'm no engineer though. I'd have to be well researched before I started getting froggy like that haha.
> 
> ...


Ayuh,... It still won't work...
With the natural convection of the fire, which is downward at the outside of the fire, 'n upward through the center, won't push Any hot air into yer tubes...

Then you have the problem with the tubes movin' heat...
Stagnant air don't move heat, it's a better insulation than anything...
If ya leave the outer most ends of the tubes open,...
They'll become draft tubes, haulin' in cold air to feed the fire...

It sounds to me like yer tryin' to Over-engineer it...
Build yer fire pit, 'n enjoy it...
If yer cold, throw some more wood on it...
Get it big enough, 'n folks will be movin' Away from it, 'cause it'll be Too Hot any closer...


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## BriBri (Dec 13, 2011)

Bondo said:


> If yer cold, throw some more wood on it...
> Get it big enough, 'n folks will be movin' Away from it, 'cause it'll be Too Hot any closer...


Sometimes it's just best to apply the K.I.S.S. principle.


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## Bondo (Dec 8, 2007)

BriBri said:


> Sometimes it's just best to apply the K.I.S.S. principle.


Ayuh,.... My point, *Exactly*..... :thumbup:


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## <*(((>< (Mar 6, 2009)

Bondo is right with the natural convection of a fire. There would be a way to make it work but it is far from simple. You would need to take the design of a propane/natural gas furnace, with a finned radiator and a fan that directs air over the fins that are warmed by the fire and the output air after passing through the heated fins be piped to vents ending at your seating area. As long as your friends don't mind smelling like smoke after sitting on top of a smoker for a few hours.

Simple. Post pictures when your finished :whistling2:


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## sanjay.radia (Jul 27, 2012)

I am planning distribute the heat of the firepit to folks sitting around the fire pit.
I was thinking of running tubes with a fan that forces air through the tubes and the tubes come through the sides of the firepit wall and blow out to folks sitting around the fire pit.
Tubes with fans are are used for normal fireplaces.
Here I will have build custom tubes.
I was thinking of ring with spoke tubes coming off the sides, with one of the spokes connected to fan - perhaps this spoke goes underground out a few feet behind the seating wall where the fan is connected.

Will this work?
What material should I use for the tubes? Steel? Copper?
Where do I place the ring? right within the fire or along against the inside of the firepit wall?


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## Bondo (Dec 8, 2007)

sanjay.radia said:


> I am planning distribute the heat of the firepit to folks sitting around the fire pit.
> I was thinking of running tubes with a fan that forces air through the tubes and the tubes come through the sides of the firepit wall and blow out to folks sitting around the fire pit.
> Tubes with fans are are used for normal fireplaces.
> Here I will have build custom tubes.
> ...


Nope,.... as discussed above,....


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## sanjay.radia (Jul 27, 2012)

Bondo
Thanks for your reply.
One thing that is different from the first proposal is that the pipe i am mentioning are fully connected - hence the normal convection airflow does that you mentioned fro the first proposal not apply. 

The air inside circular pipe which it in the firepit will obsorb the heat form the fire - new air is being forced in from one of the spokes on the circular pipe and the out of the other spokes. 

The main issues I thought would be - 


is there sufficient heat on on the sides of fire where the circular pipe is. I would be worried to keep the circular pipe in the fire itself as it may melt if not of the right material.
Would the hot air come out of all the spokes or only the first few.
thanks


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## AGWhitehouse (Jul 1, 2011)

The hot water loops are your best bet.

The ducts will work as intakes as the heat rising from the fire itself will create a negative air pressure where you are planning to locate the ducts. Plus, even if you did get it to work, trying to regulate the heat flow will be difficult and you will have to control your fire very well to ensure your seats don't get too hot. And then you also have to consider the parts of the season where you don't want heated seats, if the seats are on top of the flue, then you can't have a fire if you don't want heated seats.

With the hot water loops, you can (budget worthy of course) create custom loops for each seat with a flow controller or thermostat controller. If you don't want heat, you turn it off, if you do, you turn it on. The fire can be big/small and it had no relative effect to seat temperature.


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## Bondo (Dec 8, 2007)

sanjay.radia said:


> Bondo
> Thanks for your reply.
> One thing that is different from the first proposal is that the pipe i am mentioning are fully connected - hence the normal convection airflow does that you mentioned fro the first proposal not apply.
> 
> ...


Ayuh,.... You don't say where you are,... 
Yer environment maybe different than the 1 I live in,....

Here in the Northeast US of A,... 
Trees are generally weeds, 'n will grow on 'bout Any ground not regularly tread upon....
Wood, is available for Free to anybody with a chainsaw, 'n abit of imagination, 'n the balls to ask the property owner...
Then there's government lands, power lines, gaslines, land clearin' operations, loggin' scraps,,...
'ell,... dead wood layin' on the side of the road is fair game....

If yer Cold with yer firepit,....

Throw on another log,..... yer tryin' to reinvent,......... Fire.......:wink:


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## jburchill (Oct 3, 2010)

I say give it a try, if it doesn't work it doesn't work. I am interested if this will work. I haven't heard of this being done, so you could be the first. Also what is the distance of the these vents?


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