Have you been searching for more information about fire pit BTUs? then you have come to the right place.
There is perhaps nothing in this world like the warm and beautiful atmosphere that comes with sharing a cold evening outdoors with friends around the flickering flames of a fire pit.
Such evenings birth treasured memories and unforgettable experiences that you’d love to repeat every other night.
However, your fire pit plays a crucial role in this and must be up to the task. But then, there's the issue of the popular term 'BTU,' which is always thrown around when discussing fire pits and heat outputs. What does BTU mean?
How does BTU tie into the efficacy of your fire pit in creating the perfect ambiance on a cold winter evening?
'BTU' – meaning 'British Thermal Unit' – has been used extensively for centuries. It is still used today as the primary standard for measuring precisely how much heat a particular source generates.
BTU describes the heat output of an electric heater, a natural gas fireplace, or – in this case – a fire pit, to name a few.
So, what is BTU? Do other types of BTUs exist? How many BTUs should a particular fire pit have, and how is it even related to flame height? These are what you are about to discover in the following paragraphs.
What are BTUs?
BTUs – or British Thermal Units – refer to the amount of heat or unit of thermal energy required to lower or raise the overall temperature of one pound of pure water (0.454 kilograms) by one degree Fahrenheit (0.555 degrees Celsius) at sea level.
This implies that BTU describes both cooling and heating elements, though its more frequent usage is for heat output. This may sound somewhat complicated, but it isn’t.
BTUs are ways of measuring precisely how much thermal energy or heat an object, or something emits. This measurement can be incredibly useful, especially when it has to do with fire pits, fireplaces, barbecues, etc.
Types of BTUs
Several types of BTUs exist. One BTU or British Thermal Unit is equal to approximately 0.293 joules per hour or watt-hours and more or less equal to ten 100-watt incandescent light bulbs that run for precisely one hour.
Another frequently used unit of measurement is millions of BTUs per day. This power is enough to heat as much as 3 gallons of water from freezing point, i.e., 17.778 degrees Celsius – to boiling point – i.e., 100 degrees Celsius – in a single day.
How Many BTUs Should a Fire Pit Have?
A fire pit is not designed to emit heat just for the fun of it. It must emit just enough heat to warm every individual within a reasonable radius, as well as any food you are cooking.
But then, no one wants to get roasted alive. This is why it is crucial to learn precisely how many BTUs a particular fire pit has. This will help you and your guests feel warm comfortably throughout the evening with no thoughts of getting sautéed.
For most heating elements, especially those fueled by electricity, natural gas, propane, or ethanol, you will discover that BTU output is measured in the thousands. The higher the number, the more warmth your feature will emit, and vice versa.
For instance, the heat from one candle is not more than 1 BTU. A daily 1,500-watt floor heater will provide nothing less than 5,000 BTUs of comfortable heat.
Portable patio heaters usually emit up to 40,000 BTUs, while medium-sized fire pits for commercial or residential use emit as much as 90,000 BTUs on average.
BTU output generally ranges from 30,000 to 100,000 on an outdoor decorative appliance or fire pit. This affirms the earlier statement: the higher the BTU, the more warmth you will feel from your fire pit.
Therefore, if you own or use a propane-powered or natural gas-powered fire pit, expect your outdoor hardware to have a BTU output measuring tens of thousands.
But then, answering this somewhat subjective question: 'How many BTUs should a fire pit have?' is challenging. This is because every individual has their heating preferences. Every person feels 'warm' at widely different temperatures.
Moreover, several factors can significantly impact how warm you or anyone else feels around a fire pit or outdoor fireplace. This includes – but is not limited to – the following:
- The proximity of the fire pit to you and your friends/guests
- The climate in the region you reside
- How windy it is outdoors at any given period
- Whether you use your fire pit outdoors or in a more enclosed living space
- The type of fire pit you use
The only reliable way to determine your precise BTU needs is to measure the temperature of the pit's flame using a special thermometer. Then, ask yourself how you feel. This may not be subjective, but that does not prevent you from applying some science to it.
A standard outdoor fire pit – powered by a gas such as propane or natural gas – should feature anything from 40,000 BTUs to 150,000 BTUs worth of heat output or thermal energy. This is a wide range for a good reason.
A fire pit with at least 40,000 BTUs is ideal for small decks and patios. But for med-large patios or decks, go for a fire pit with guaranteed outputs between 60,000 and 100,000 BTUs. Large patios and decks can work with fire pits with up to 150,000 BTUs.
BTU Relation to Flame Height
Have you ever wondered if BTUs directly impact the height of the flame your fire pit emits? If you have, fret not because you are about to discover the answer.
BTUs do have a direct relation to flame height, implying that the higher the BTU, the higher you should expect your fire pit flames to rise.
However, several other factors also govern flame height. Here are some of these factors:
- Large apertures or orifices mean more BTUs to the burner, assuming every other thing remains constant or the same.
- Natural gas (1,000 BTU/ft.3) has far fewer BTUs per cubic foot than liquid propane (2,500 BTUs/ft.3).
- Higher gas pressure implies more BTUs to the burner, assuming every other thing remains constant.
- Before the fuel is burned, the amount of air mixed directly with the gas that fuels the fire pit significantly affects the flame height and overall color. The more air mixes with the gas, the bluer the flame color and the shorter the flame height will be.
It will also be a higher temperature and cleaner flame. More air is usually added by opening the air shutter at the aperture location. Close the air shutter if you want less air to mix with the gas. This will cause the brighter yellow flame to become taller.
It is never advisable to close out the air shutter for too long as the outcome may be a dirty, sooty flame. Although this may still be far cleaner than a wood-powered flame, it is still dangerous due to the carbon dioxide it generates.
- Liquid propane is typically used at 10 inches to 11 inches of the water column.
- Natural gas is generally used at 3.5 inches to 7 inches of the water column.
Liquid propane and natural gas are generally sold by the BTU. This implies that the more BTU a specific burner uses per hour, the more it costs to burn the appliance.
The size of your gas lines and orifices, the fire media utilized and the way it is laid, as well as the distance your fire pit is from its fuel source, also determine the flame height.
Lastly, safe positioning also plays a crucial role irrespective of the BTU output your fire pit generates – the kind of fuel it consumes. This is primarily down to the overall size of your outdoor living space.
Ensure you position your fire pit in an open area devoid of stray debris or additional structures. If you leave your fire pit near a structure, flickering flames or an ember can catch something else suddenly and cause an unwanted or unexpected catastrophe.
Therefore, ensure you position your fire pit at least 15 feet or even more away from outdoor structures or trees. If you own a fire pit with a higher range of BTU output, position it even further away for a more uniform ambiance.
If you must position your fire pit near any outdoor structure, ensure those structures or furnishings are made from fire-resistant materials.
While all you want is a high BTU measure for your fireplace or gas fire pit, many other factors are also crucial to consider when shopping for a suitable fire pit. You should also note that not every outdoor gas burner effectively utilizes air shutters.
In simple words, BTU output is directly proportional to the height of the flame, even though other factors also affect this outcome.
Which Fuel is Right for Your BTU Needs?
Every flame needs fuel to flourish, including your fire pit. But to get the most out of your fire pit, you need only to use a highly efficient fuel so that it burns well and generates comfortable heat.
Let’s check out the different types of fuel that power fire pits these days:
- Natural Gas and Propane
Gas fire pits are natural choices for many as they are very affordable and offer easy clean-ups. You do not need to break the bank searching for the fuel to power your fire pit since gas – i.e., natural gas and propane – are readily available.
However, even though fire pits can be incredibly expensive, they require less work down the road. They will most likely save you a lot of your hard-earned money, especially if you frequently use your fire pit.
A propane fire pit can generate from 40,000 to 150,000 BTUs. But then, a natural gas fire pit has an output that ranges from 30,000 to 60,000 BTUs, especially if it is used for cooking and heating.
Wood-powered or wood-burning fire pits are also an excellent choice. No one can really put a finger to it, but there is something homey and lovely about a wood fire going at night.
Moreover, wood is a natural and cheap resource that burns pretty efficiently. Wood can burn so hot that your fire pit stops producing a lot of ambient smoke, creating what is popularly known as 'smokeless fire pits.'
It is possible to adjust the BTU output of a wood-burning fire pit by reducing or adding to the amount of fuel, i.e., wood.
However, it is worth noting that wood-burning fire pits require relatively intensive upkeep. Sourcing wood can also be expensive – as you need to keep buying it from time to time in order to keep enjoying warm, eventful evenings – and pretty challenging.
Wood-burning fire pits generate from 30,000 to 100,000 BTUs, ideal for people of all ages to enjoy, thanks to the traditional look and warm cozy environment.
In a gel and liquid form, bioethanol fuels burn a lot less intense than other alternatives. If your fire pit uses bioethanol as its primary fuel source, you should expect lower BTUs.
The exact details/factors hold for heaters powered by electricity, though this depends partly on the heater's power.
BTUs are considered the industry standard for measuring the thermal unit or heat output.
The higher the BTUs of your fire pit, the more warmth you and your friends or guests will enjoy, whether outdoors or indoors.
You can increase the amount of heat your fire pit produces in several ways.
But the most important factors to consider are the type of fire pit you use, the fuel that powers it, and the primary air you allow to mix with the gas, i.e., if you use a gas-powered fire feature.
Bear in mind that the BTU outputs of each type of fire pit, as outlined in this article, are based primarily on wind conditions and outside air temperature.
For instance, if you have a 2 breeze – even though it is up to 95 degrees Fahrenheit outside – you may lose up to half of the total BTUs as a result of frictional heat loss.
Check out the Ultimate Guide to the Best Electric Fire Pits