How hot a fire pit gets is determined by the fuel you use and the construction of your fire pit. Bioethanol fire pits burn at the lowest heat, reaching 4,000 BTU. Wood fire pits (difficult to precisely measure) can get over 100,000 BTUs (900◦C or 1650◦ Fahrenheit). Gas fire pits at a small-scale burn up to 10,000 BTUs, while commercial-sized gas fire pits get up to 70.000 BTUs.
Fire pits are a great way to move your living space outdoors all year round or warm a small indoor space. They are functionally designed and come in many shapes, sizes, materials, and designs. Fire pits are great for hosting parties, roasting marshmallows, enjoying family time while keeping warm, or creating an inviting atmosphere with the dancing orange flames.
Suppose you are concerned about how hot your fire pit gets or does not get. Whether it will melt your metal marshmallow sticks, burn too hot for yearly use, or leave you cold. Or you are someone looking to add a fire pit to your yard for the cooler months and would like to know the heat ranges of different types of fire pits. Follow along as we discuss how a fire pit gets hot and what makes specific fire pits more desirable than other types.
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How Hot Do Fires Burn?
Fires in fire pits start burning at 1,000 BTUs and can burn over 100,000 BTUs.
When answering how hot fire can burn, we must remember that certain variables influence the heat produced. The variables that affect how hot a fire pit gets are (1) the choice of the fuel used and (2) the construction of our fire pit. These factors will determine how big the flames burn and if there is any residual heat.
Many different fuels can be used, including wood pellets/chips, wood, gases (fireplace ethanol and propane), charcoal, smokeless coal, and biofuels. The most popular choices are wood and gases. Fire pits can be built from materials such as lightweight steel, masonry, or any sturdy, fireproof material.
We measure the heat produced from fire pits in British Thermal Units (BTUs), as it is more precise than measuring degrees Celsius or Fahrenheit. BTU is the total amount of heat required to increase the temperature of one kilogram of water by one degree Fahrenheit or to raise the temperature of one kilogram of water by one degree Celsius. BTU is universally used to measure heat and cold for multiple products.
Types Of Fire Pit Fuel
Bioethanol fire pits burn between 1,000 and 4,000 BTUs, the lowest heat of all available fire pits. These fire pits function more as a decorative piece than a heater. Bioethanol fire pits generate less heat as the flames are smaller due to the small amount of fuel they use.
These fire pits are not designed for outdoor use but can be instead used to heat a small room or create a warm and cozy atmosphere.
Propane fire pits are available in different sizes and decorative options. These fire pits burn between 10,000 and 70,000 BTUs.
Smaller propane fire pits burn at 10,000 BTUs, which are also more for decorative purposes than generating enough heat to keep you warm. Standard propane fire pits available for home use burn at 30,000 BTUs. More giant propane fire pits can burn at up to 70,000 BTUs.
Propane fire pits are a popular choice as they are easy to light compared to wood fire pits. You can control the heat through flame size, there is no smoke or ashes produced, and they are easy to clean. Propane is natural gas, so these fire pits are cost-effective.
A big advantage of a propane fire pit is its ability to emit heat after it has been switched off due to the lava rocks or glass rocks installed in the pit.
It is difficult to pinpoint precisely how hot wood burns due to its variable nature. Wood is estimated to burn at over 1000,000 BTUs (900◦C or 1000◦ Fahrenheit), with the size of the fire built, the type of wood, and the oxygen affecting how hot it burns.
A massive fire pit will result in a bigger flame and thus a hotter fire. Wood requires 15% oxygen to burn, with the percentage of oxygen in air being 21%. The more air that can move around the fire, the greater the heat output will be.
It is thus recommended to place your wood fire pit in the center of your garden, where the air can circulate appropriately if you would like a hot burn.
Wood as a fuel source is readily available and burns easily. Types of wood include softwood, hardwoods, and resinous. The dryness of the wood (green or seasoned) is also important as greener wood contains more moisture than seasoned wood. Compared to softer or green lumber, harder and more seasoned woods burn better, producing higher temperatures.
The flame produced by wood is a bright orange-yellow, with harder woods like oak or hickory burning at the highest BTUs. Wood typically has a more significant fire than gas or propane, thus emitting more heat.
Woodfire pits may prove less of a choice as they produce smoke and ash, which may be harmful to those who have asthma. Cleaning up ash every time you make fire may also be a deterrent.
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Unlike all the other fire pits, gas fire pits need to be stationary, as gas is fed to the fire pit from a gas line attached to your house. Natural gas, in some places, is more cost-effective than other fuel options, and you are not going to run out. Gas is not as efficient as propane as it burns at 1000 BTUs, compared to 2500 BTUs for the same volume.
Gas flame size can be controlled, unlike wood fires. Large models of gas fire pits have glass or lava rocks that absorb heat and will continue to radiate heat passively. You can tell if your gas pipeline is clogged as the flames will flicker blue.
Gel fuels are newer to the market and are a mix of water, salt, binders, and isopropyl, producing a yellow flame. They are able to burn up to 3 hours, and their flames burn up to 3,000 BTUs. If your gel fuel contains pure alcohol or ethanol, the flames will burn at 4,000 to 5,000 BTUs, be thinner and orange-yellow in color, and last up to 5 hours.
Gel fuels are bought in a compressed canister instead of a tank, which is seen when using gas.
The use of biofuels such as other corn-derived and ethanol fuels is becoming popular in a move to be more environmentally friendly and reduce carbon footprints. Biofuels burn with little odor and have a natural-looking orange flame. Ethanol burns at approximately 6,000 BTUs.
Biofuel flames can be controlled to produce less or more heat, depending on the design of your fire pit. Biofuels are also economical, with one liter of biofuel able to produce 4 hours of burn time on high heat or 8 hours on low heat.
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Types of Fire Pit Housing
The amount of heat that can radiate from the fire pit is partly due to the shape, size, material, and overall structure of the fire pit and the fuel used. Two of the most used materials for fire pits include masonry and steel.
Masonry fire pits are designed to absorb radiant heat from the flames, which release heat even after the fire has died or been turned off. Masonry fire pits consist of a metal firebox cased/enclosed by your choice of paver of brick. These fire pits are constructed to look more attractive and are the more expensive option to build.
Fire pits constructed from steel often are in the shape of a bowl and are free-standing. Steel-constructed fire pits are more cost-effective than masonry fire pits. To avoid being toppled over, free-standing fire pits should be closer to the ground.
The right type of fire pit for your house will depend on your budget, how frequently you want to use it, and where you want to put it. You also need to check if there are any bylaws in your neighborhood stipulating what you can burn or how big your fire is allowed to be.
How hot a fire pit burns depends on what fuel you use, how much of the chosen fuel you use, the material your fire pit is constructed from, and the size and shape. The fuel you choose to use in your fire pit is significant as fuels like wood burn with a bigger flame than bioethanol, which burns with a smaller flame.
If you are looking for a pretty fire that does not get hot enough to keep you warm, a bioethanol fire pit is excellent. If you are looking for a fire pit that burns hot, long and you don’t mind the smoke or clean up, a seasoned hardwood fire will be perfect. Propane fire pits provide a more versatile option than all other fuels mentioned.