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?? Basic plans for a fire pit?

Posted by tsunami (My Page) on
Thu, Oct 2, 08 at 1:18

I'm in the process of roughing in a fire pit before the deck goes in and would like to know some of the basics. I've already dug the trench for the gas line @ 18" deep. Next, I'll be digging for the drainage. I have a 3" drain line about 6 feet away that I can tie into. Should I cover it with pea gravel? What height should I stub the gas riser and the drain line at? Should I use perforated pipe with a sleeve over it? Would the heat melt the pipe? What about air vents?I can't seem to find any basic details online for building a fire pit. Any details would be helpful.


Follow-Up Postings:

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RE: ?? Basic plans for a fire pit?

tsunami-

I am working on our DIY fire pit now. I used 2" PVC pipe for both the drain pipe and the gas/electrical lines. Both pipes were placed in the trench adjacent to one another and I roughed them in to protrude about 1 foot above the stamped concrete. After decking was complete, I cut the drain pipe flush to the concrete and left the gas/electric pipe above the concrete about 2".

We picked out a 36" diameter clay fired bowl from a local outdoor store and chipped a hole in the bottom of it about 8" in diamter. Now the bowls sits on the concrete with the hole centered over the PVC pipes.

Ours will also be gas fired with a 30" fire ring resting on a 32" stainless steel pan which fits nicely into the 36" fire pit bowl with about 12" of clearance between the bottom of the pan and the concrete. This space underneath the pan will house the gas valve and direct spark ignition module. It will also be automated and controlled through our pool automation system and can be turned on with our pool handheld remote.

The bowl, fire ring, pan and lava rock have all been placed. I have all the hardware now and just need to mount them in the firepit and run the gas and low voltage electric line. I am not worried about the components underneath the stainless pan getting too hot because the bowl is open and the heat will rise rapidly upward without restriction.

I will be posting some pics of it soon on my pool thread in addition to detailing all the components and sources for the components that were used to construct the complete fire pit.

Keep checking below link.

Hope this helps!

Here is a link that might be useful: New Pool in Louisiana


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RE: ?? Basic plans for a fire pit?

Any pvc or plastic within the area of the fire is going to melt. It sounds like your plaining your drain at the grade level of the pea gravel...is that true? Thats pretty much at the level of the fire ash as well and it will melt, even if you make this metal, it will conduct heat and dirt is an excellent heat insulator. That means you could end up conducting heat along a metal pipe length all the way to the plastic junction box.

I built my own mortar "wood burning" firepit and the way I dealt with this is simply drilled in holes in the mortar around the sides that would allow the water to channel out of the middle of the firepit. These will also act as air vents although I think the real key to that is to not make the fire pit deeper than 18" max and to make the pit oversized in width so that the fire takes up a smaller space of the entire size of the pit. Thus you have lots of air space around the sides. If you build the sides tight up against the fire ring, then you will definetly need to provide some air.

Here is a link that might be useful: DIY Firepit


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French drain

Since you are doing gas, you probably could build a french drain...where the perforated pipe was about 6 inchs below grade and filled with pea gravel to grade. I think 6 inches of pea gravel insulation would do ok with gas-only heat. I think I probably would put two or three perforated pipes in parallel tied together on one end would do it.


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RE: ?? Basic plans for a fire pit?

barco-

Yeah....my setup is definitely gas and not wood burning. I've seen many gas firepits in resorts that are constructed with PVC pipe like I described. There is about 12" between the stainless steel pan and the PVC pipes and the fire ring is on top of the pan and open to atmosphere. There is a 1" air gap between the pan and the clay fired bowl going around the entire 30" circumference of the stainless steel pan to allow ventilation for the space below that is housing the electronics and gas valve.

I did consider, using stone to fill up the bowl then set the gas fire ring on top of it. This would have saved $300 for the stainless steel pan. But I wanted to have easy access to the ignition control module and gas valve underneath when needed.

Regarding drainage, I just ran the 2" PVC drain pipe that goes underneath the stamped concrete out to a french drain in the woods. There is not that much drainage that is needed for the 36" diameter bowl even during our monsoon rains here in Louisiana.

Here's some pictures that may help describe our gas fire pit setup a little more clearly.

The spark ingnition module and the automatic gas valve will be housed underneath the stainless pan you see in the picture.

Not sure if this is what you had in mind tsunami?

Hope this helps!

Photobucket

Photobucket


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RE: ?? Basic plans for a fire pit?

trhought,

Could you give the specifics on the bowl, ring and ignition? I have searched the internet, but have been unable to locate a bowl. I have been unable to locate one locally as well. Any info. on the other items would be apprerciated.

THANKS!


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RE: ?? Basic plans for a fire pit?

eyoung-

Here's a link to the store where I purchased the bowl. I don't think they deliver but any nearby outdoor specialty store should have a selection of outdoor bowls to chose from. Just make sure it is a clay fired bowl so it can withstand the heat and tell them what you are using it for so they can make recommendations.

http://www.cornercollectiononline.com/gsb.htm

The fire ring kit and feather rock was purchased from fire pit outfitters per link below. They do deliver and I ended up with one of the manual spark ignition kits instead of the electronic ignition kits. When you see the pricing, you'll know why! There is also a match lit kit if your budget is tight and you don't mind manually opening the gas valve and lighting the fire ring with a match. Note, the manual kit does not have any flame out protection, so if the flame does go out, the valve will have to be shut off manually to prevent gas from flooding the area and creating a hazardous situation. Both the direct spark ignition and electronic ignition kits have flame out protection.

http://firepitoutfitter.com/index.asp?PageAction=COMPANY

I then converted the manual kit over to an electronic kit using the components below. Note, you can also buy the electronic ignition kit directly from firepit outfitters but it will cost a lot more than the conversion components I describe below. The advantage, of course, is you won't have to hassle with the conversion and you'll know that the kit will work out of the box if installed properly.

Here's the electronic conversion parts. These parts can be found online or at a local HVAC Center or Appliance Parts Center.

Gas Valve - Electric
Direct Spark Ignition Control Module with flame out detection
Flame Sensor - Electric

The manual spark ignition kit already has a spark ignitor included in the kit but the flame sensor with the kit is a mechanical one so it needed to be upgraded to electric.

The ignition control module will be controlled by our pool automation system and turn the fire pit on/off with the hand held pool remote.

Also very important, allowances for air flow are critical to ensure the temperature does not exceed 175 degrees F where the electronics and gas valve are housed to avoid damage to them. This includes adequate intake openings at the bottom of the bowl to allow cool air in and adequate openings around the pan to allow the hot air to escape upwards without restriction.

If any of this does not make sense, I would recommend consulting with a local professional such as an electrician, plumber or HVAC technician who has experience making these parts work together safely.

Hope this helps!


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RE: ?? Basic plans for a fire pit?

I'd like it to be automated but am having second trhoughts. :) The price is outrageous! A 24" stainless kit with electronics runs about $2K. And that's without the bowl, stonework, etc.

I went to a local fireplace store and got some advice from one of the installers there. He recommended a 6" clearance between the fire ring and the inner diameter of the fire pit for air. With that you'd use a 24" ring with a 36" diameter pit. The ring should be 3" below the top of the fire pit resting on the pea gravel to support the ring.

He said that the electronic igniter unit is a great idea, but of the few installed around here(San Diego coast), most have problems due to the moisture screwing up the electronic unit or the contacts at the top.

trhought, how much are you saving by converting the manual unit to an electronic igniter? Are you going to build anything around the clay bowl? Thanks for the ideas.

barco, good idea! I'm probably going to dig the drainage trench in the shape of a U around the gas line Using perforated pipe with a sleeve over it to keep the dirt out, fill it with pea gravel to grade level, and tie it in to the closest drain. I'm not quite sure how I'm going to build the firepit yet.


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RE: ?? Basic plans for a fire pit?

tsunami-

Yes....the automated kits are expensive. You are paying for the technology and for pre-assembly. The 30" manual spark ignition kit was $700 and the electronic parts to convert to fully automatic were $200. The bowl was $100 and the feather rock was $50. So full cost will be about $1K plus the cost to run gas line and electric lines.

The clay bowl will sit as you see it in the picture with nothing else around it. It will be raised about 4" with feet that will allow cold air to be pulled into the bottom of the bowl when the fire ring is lit. The key to keeping the electronics and gas valve cool is to place them close to the cool air intake at the bottom of the bowl. The kit manufacturer recommends this intake be no smaller than 15 sq. in. (3"x5" notecard) to allow enough cold air flow into the bowl. Also, allowance for hot air to escape is needed which is why I have the 1" clearance between the pan and the inside of the bowl all the way around.

The setup your local fireplace store recommended (24" ring with 36" bowl) sounds about right. The outer fire ring in the picture above is 24" in diameter and my bowl is 36" also, so that should give you an idea how this will look.

If you go the electronic ignition path, just make sure to allow for the air flow I describe above, which will not be possible with pea gravel.

However, if your bowl is taller, the pea gravel may provide enough insulation between the control box and the fire ring. So maybe if the control box is placed in the bottom of the bowl with gravel on top, that may be enough to keep it cool, but I'm not sure how tall the bowl would have to be to make this work...I'm guessing the bowl would have to be around 2.5 feet tall to allow about 18" clearance between the bottom of the fire ring and the top of the control box with pea gravel in between....just a guess.

As a reference point, our bowl is 42" outside diameter, 36" inside diamter and is 14" tall.

If you want other ideas, there is another manufacturer that sells fully automated fire pits ready to go, bowl and all. Google "grand effects" for this company. When I priced 2 years ago, the starting price was around $3.5K for a bowl smaller than ours....ouch!

Hope this helps!


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RE: ?? Basic plans for a fire pit?

Try Fire by Design out of Las Vegas. They have some proprietary systems that are wonderful and the price has come down. www.firebydesign.com


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RE: ?? Basic plans for a fire pit?

Thanks for the links!


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