Turn dry prunings into biochar. Filmed with our 24-inch fire pit; the large one works the same way, at eight times the volume.
Large Biochar-Making Fire Pit
$1,500.00
Sale price
$1,500.00
Regular price
Skip to product information
Large Biochar-Making Fire Pit
$1,500.00
Sale price
$1,500.00
Regular price
Shipping calculated at checkout.
Description
The Biochar-Making Fire Pit, scaled up for a landowner with more prunings than a backyard fire pit can keep up with.
This is the same flame-cap kiln as our 24-inch fire pit, about eight times the volume: a hexagonal cone 48 inches across the rim and 25 inches deep, in 11 gauge steel, holding about 90 gallons (340 L) of wood to the rim. Dry prunings, orchard trimmings and clean scrap wood go in a layer at a time; water from the hose puts it out; biochar for your soil comes out. A flame-cap kiln works through about 4 to 8 times its own volume of wood in a batch, so one batch in this fire pit can take care of roughly 2 to 3 cubic yards of dry brush.
Built to order. We build each one in our shop in Salem, Oregon, when the order comes in: about five weeks to build, then about a week in transit by freight. The pictures are renderings, not photos. We designed this fire pit for a customer who asked for a larger one, and the first one has not been built yet, so there are no product photos to show; what you see is the model it will be built from. For a sense of how it looks for real, the welds, the steel and the rust patina, have a look at the photos of our 24-inch Biochar-Making Fire Pit: this is the same design and the same shop, scaled up. The photos and videos further down this page show that 24-inch fire pit in use; the large one works the same way, at about eight times the volume.
A biochar kiln for sale that is sized for acreage, not a city lot
Most biochar kilns for sale at this size are ring kilns or drum retorts. This one is a Kon-Tiki biochar kiln at heart: a flame-cap cone, open at the top, wide at the rim, with the same bottom-up quench as the small fire pit. It is meant for a small landowner, an orchard, a few acres of woodlot or a market garden with a steady supply of prunings, not commercial volume. If you are looking for a commercial biochar kiln for sale, the buyer's guide lists the field-size kilns instead. It is also bigger than most cities allow for a backyard fire pit (many cap open fires at 2 by 2 feet), so check your local rules before you order. Where a fire this size is allowed, it makes far less smoke than a burn pile.
What makes it work
- Makes biochar the same way as the small fire pit: start a fire, add a layer of wood each time the flames die down, and quench from the bottom up through the built-in pipe. Expect roughly eight times the char of the 24-inch fire pit per batch (its range is 2 to 4 gallons); how much you get depends on how dry the wood is and when you quench.
- Removable handles: four 1-inch steel pipe handles slide into welded sockets and lock with a pin and keeper, so two people can move it when it is cold. Pull them out for the fire and for shipping.
- 11 gauge steel: about 1/8 inch, twice the thickness of the small fire pit, for a fire that runs a lot hotter and a lot longer.
- Bottom-up quench: a brass fitting for a standard 3/4-inch garden hose. A 90-gallon cone fills in about 10 to 20 minutes on a garden hose, and the water comes up under the char so every piece gets wet.
- Made in the USA: we build each one in our shop in Salem, Oregon, from US steel.
Bare steel: left outside it weathers to a rust patina meant to blend into a field or a garden, the same as the small fire pit.
How it ships: freight by region, or pick it up in Salem
At about 175 lb it goes by LTL freight, strapped open to a 48 by 48 inch pallet (about 250 lb with the pallet; the pallet is included in the price). At checkout you choose one of two freight rates for your region: pick it up at your nearest freight terminal, which is the least expensive and the most reliable, or liftgate delivery to your home, where the driver lowers the pallet to the ground at the end of your driveway. The rates by region are in the Shipping tab below and show again at checkout. Or pick it up free at our shop in Salem, Oregon: choose Pick up at checkout and we call you to set a time when the build is done. Alaska and Hawaii: email us for a quote before you order.
Learn more about biochar gardening on our Biochar Blog, read how to make biochar at home, or compare a Kon-Tiki kiln, a retort and a TLUD in the biochar kiln buyer's guide. For a backyard, the 24-inch Biochar-Making Fire Pit is the small biochar kiln of the two and ships free by ground. Want something smaller? That is the one.
Specifications
| Rim | Hexagonal, 48 in (122 cm) corner to corner, about 42 in (107 cm) across the flats |
|---|---|
| Height | 35 in (89 cm) overall; 25.5 in (65 cm) inside depth |
| Volume | About 90 gallons (340 L) to the rim, about 8 times the 24-inch Biochar-Making Fire Pit (11 gallons) |
| Steel | 11 gauge mild steel, about 1/8 in (3 mm); welded, one piece |
| Weight | About 175 lb (79 kg) without the handles; about 250 lb (113 kg) on the pallet |
| Handles | Four removable 1 in steel pipe handles that slide into welded sockets and lock with a pin and keeper. Take them out for the fire and for shipping |
| Quench inlet | Brass swivel fitting for a standard 3/4 in garden hose. Water fills the fire pit from the bottom up |
| Finish | Bare steel. Left outside it weathers to a rust patina meant to blend into a field or a garden |
| Built to order | About 5 weeks from payment, then about a week in transit by freight. Pictures are renderings; the first one has not been built yet |
| Shipping | Strapped open to a 48 by 48 in pallet, by LTL freight; pick it up at your nearest freight terminal or have it delivered to your home with a liftgate (rates by region in the Shipping tab). Free pickup in Salem, Oregon |
| Made in | Salem, Oregon, USA |
| Returns | Built to order, so it is not returnable once built. Damage in transit or a defect: we repair or replace it at no charge |
| Warranty | Five-year limited warranty on materials and workmanship (terms) |
Shipping and pickup
It ships by LTL freight on one pallet, 48 by 48 inches and about 250 lb, strapped open (no crate; the pallet is included in the price). At checkout you pick one of two flat rates for your state:
- Pick up at your nearest freight terminal. The least expensive and the most reliable option. We book the carrier, the pallet waits at the carrier's terminal nearest you, and you collect it with a pickup or trailer and a helper; the terminal forklifts it on. We email you the terminal address and hours; most terminals hold a pallet free for a business day or two, so plan to collect it promptly.
- Liftgate delivery to your home. The driver brings it to your address on a truck with a liftgate and lowers the pallet to the ground where the truck can safely reach, usually the end of the driveway. Someone needs to be home to sign, and the carrier calls ahead to set a window.
| Region | States | Terminal pickup | Liftgate to your home |
|---|---|---|---|
| Northwest | OR, WA, ID | $295 | $490 |
| West | CA, NV, UT, AZ, MT | $370 | $545 |
| Mountain and Plains | WY, CO, NM, ND, SD, NE, KS, OK | $475 | $645 |
| Midwest | MN, WI, IA, MO, IL, IN, OH, MI | $500 | $600 |
| South | TX, LA, AR, TN, KY, MS, AL, GA, SC, NC, FL | $555 | $675 |
| Northeast and Mid-Atlantic | VA, WV, MD, DE, DC, PA, NJ, NY, CT, RI, MA, VT, NH, ME | $575 | $785 |
One flat rate per fire pit, chosen at checkout. Enter a daytime phone number at checkout: the freight carrier calls you to arrange the pickup or the delivery. If no carrier holds freight for pickup near your ZIP code we book to the nearest terminal that does (it can be 100 miles or more in the Mountain West, the Plains, eastern Oregon, central Idaho and northern Maine) and email you the terminal city before we build; you can switch to home delivery for the difference. Island, ferry and other addresses a 53 ft trailer cannot reach are quoted before the build starts. Alaska and Hawaii: email for a quote. Free pickup at the shop in Salem, Oregon.
Free pickup in Salem, Oregon. Choose Pick up at checkout. We call or text you to set a time when the build is done; it is a two-person lift onto a truck or trailer.
Alaska and Hawaii: email contact@pifabricators.com for a quote before you order. We do not ship outside the United States.
Damage: note anything on the delivery receipt before you sign, and email us photos within 5 business days; that is the freight carriers' claim window and we take it from there.
Care and durability
How long will it last? What wears a steel fire pit is rust, and most of that is moisture between fires, not the fire itself. This fire pit is 11 gauge carbon steel, about 1/8 in thick, twice the small fire pit's. Left outside with no care at all you would get a very long time before rust became a structural concern. The one thing that shortens its life most is rainwater sitting in the bottom between uses. Keep it covered or under a roof when you can and clean the ash out, since ash holds moisture.
Will it warp? A fire this size runs hot for hours, and thin steel warps. That is why it is 11 gauge, welded in one piece. Some movement of the panels over the first fires is normal and does not affect how it works.
Can it be painted? If you prefer a painted finish over the rust patina, we recommend Rust-Oleum High Heat Ultra, on the outside only. No paint holds up to direct flame, so the inside stays bare steel.
Are you tired of:
-- Burning prunings and brush in a pile, and getting nothing back but ash?
-- Hauling organic matter off your land that could be feeding your soil?
-- Paying for soil amendments that do not last?
Made for your land
An orchard, a woodlot, a market garden or a few acres of pasture makes more prunings and brush in a year than a backyard fire pit can keep up with. This one takes a wheelbarrow of dry wood in a layer and turns a season of cutting into biochar for the soil it came from, with a fire you can sit next to while it works. Rendering shown; the first one has not been built yet.
What biochar can do for your soil
The illustration above shows several common soil problems biochar can help address — poor water retention, nutrient leaching, compaction, and weak microbial activity. Your soil may not have all (or any) of these issues, so results will vary depending on your starting conditions.
To see how biochar is likely to perform in your garden, use our interactive soil map. Click on your location and get an estimate based on regional soil characteristics.
Make Biochar
Make your own biochar from a season of dry prunings, orchard trimmings and clean scrap wood.
Have Fun
Enhance your social life with fire pit gatherings or simply enjoy the calming effect of sitting next to a fire.
Lower your Carbon Footprint
Biochar is a stable form of carbon that can last for thousands of years in soil.
Start the fire
The photos in these three steps show our 24-inch fire pit; the large one works the same way, with more wood in each layer. Like any fire pit you start your fire with tinder such as small twigs or newspaper and get a base burning. Add larger branches or firewood once the fire gets going.
Add wood
As your fire burns you will see how it burns down with reduced flames making a char bed. Each time it settles down add a little more wood to the fire.
Quench
Start reducing the diameter (thickness) of the wood you add about an hour before you plan to quench. Then quench with the attached hose, filling the fire pit with water from the bottom up until every piece is wet.
How to make your own biochar. Filmed with the 24-inch fire pit; the process is the same in the large one.
Biochar improves your garden's soil
- Biochar increases your soils ability to hold nutrients so more of your valuable fertilizer stays in your soil helping your garden to grow.
- Biochar decreases soil acidity increasing the vitality of your garden.
- Biochar increases your soils ability to hold moisture so your plants get less stressed between waterings.
Don't just take our word for it
Sustainable biochar is a powerfully simple tool that can produce a soil enhancer that holds carbon and makes soil more fertile
Stop Paying for Bagged Soil Amendments
You shouldn't have to break the bank to improve your soil. Bagged biochar runs about $15 to $38 per cubic foot, yet the dry prunings in your yard are free. We designed a simple, fun way for you to turn fallen branches into premium soil fuel—right in your own backyard.
Want something smaller?
The 24-inch Biochar-Making Fire Pit is the backyard size: the same flame-cap design at 11 gallons, 21 lb, no assembly, $370 with free ground shipping in the continental US. It fits where most cities allow a fire pit, and it is the one in the photos and videos on this page.
Have fun while making biochar
At Pi Fabricators we know that you want healthy soil across the whole place, not just the vegetable bed, and that bagged amendments do not go far on an acre. We believe you should be able to enrich your soil with the wood you already cut. That is why we scaled the Biochar-Making Fire Pit up: the same fire you sit next to, eight times the wood in a batch. The photo shows the 24-inch fire pit.
A flame-cap biochar kiln, built on the Kon-Tiki kiln design
The Large Biochar-Making Fire Pit is a flame-cap biochar kiln: a cone in the Kon-Tiki tradition, with the Japanese MOKI cone kilns and the old soil-pit kilns as its ancestors. We stand on the shoulders of giants. It is the same design as our 24 inch backyard fire pit, scaled up for a landowner with real prunings to deal with.
Reduced smoke emissions
The flame-cap shape makes less smoke than a conventional fire pit or a burn pile* because air warms as it rises along the outward-slanted wall, rolls over the rim and mixes with the smoke coming off the flames, giving it the oxygen to burn off.
*It burns a lot cleaner than a fire ring or a pile, but it is not a double-wall smokeless pit and it is not smokeless: the milder airflow is what keeps the wood below the flames from burning to ash, so the biochar survives.
Designed for Warmth. The Difference:
Competitors (Double-Walled): Double walls found in smokeless fire pits act as insulation trapping heat and funneling it upward. Heating the sky instead of your toes.
The Biochar-Making Fire Pit (Single-Walled): Conductive steel walls radiate heat outward instantly.
The Result: You stay warm from head to toe, with minimal smoke.
Order your Large Biochar-Making Fire Pit
1. Add to cart, pick freight or Salem pickup at checkout
2. We build it, about five weeks
