Gas Pipe Size for Fire Pits

Exploring Fire Pit Gas Supply
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Why is it important to install the correct Gas Pipe Size for Fire Pits?

One of the most common questions we’re asked is ‘What size gas pipe do I need for my gas fire pit?’

The answer is often ‘much bigger than you may have thought’.

A great fire pit flame needs two things, sufficient gas, and correctly sized hard piping to deliver it. Too often the gas pipe size for fire pits is not taken into account and the resultant flame is very disappointing.

Hopefully, you are asking this question at the planning stage of your fire pit project if not the question is more likely to be “Why is my Gas Fire Pit flame so low?”

How to ensure the correct gas pipe size for fire pits

This article is about moving the gas from its source, i.e. your domestic metered supply or a large gas storage bottle to the location of your fire pit, which should be accomplished using hard piping. But what size pipe do you need?

A short example to emphasize how important this subject is:

If you have 100,000 BTU available from your gas source for your fire pit, and the fire pit is 20 feet from the gas source, you would need a 3/4″ diameter hard pipe.

If the same fire pit is 100 feet from the gas source then you would need a 1″ diameter pipe. The 3/4″ pipe over 100 feet would only deliver 68,000 BTUs! (Natural Gas), two-thirds of what is required!

For a great fire pit flame, there are two major issues to be addressed:

The BTU rating of the burner must match the BTU rating of your available gas supply

You must select the correct sized pipe to get gas from its source to the fire pit site

The following Gas Hard Piping Size For Fire Pits charts are for new gas line installations directly from the gas source. If you are connecting to an existing gas line, you must take into consideration the surplus capacity of the existing system, to ensure you will have sufficient pressure at your fire pit.

These charts are for reference only; we strongly recommend you consult with a Licensed Plumber/Gas Fitter or the NFPA54 ( National F Gas Code – current edition ) for more details.

How to use the Gas Line BTU Chart

Using the Natural Gas Chart as an example, let’s assume you are planning to install a 75,000 BTU gas burner in your fire pit project. The vertical column on the left represents the length of hard piping connecting your gas source to the fire pit structure. ( Add 5 feet to that length for every 90-degree bend in the pipe length.) The row across the top represents the possible gas pipe diameters, i.e., 1/2 “, 3/4” etc.

Starting in the left column, select the overall length of the gas pipe required. ( if your figure falls between two of the options always go for the longer distance ). Let’s say you need 110 feet of gas pipe, you would select the 125 feet figure.

Now we look to the right along the line of figures that will provide our 75,000 BTU unit with enough gas. The first figure we find is 28, which is 28,000 BTU, so that is not enough for our 75,000 BTU unit.

The next figure to the right is 60 which represents 60,000 BTU, which is still not enough for our 75,000 BTU unit, so continuing moving to the right, the next figure is 117 ( i.e 117,000 Btu ), and that is more than enough for your 75,000 BTU requirement.

Now, look up to the top row of the chart above the 117 figure, and that shows that you will need a 1″ diameter gas pipe.

The calculations are different for Natural Gas and Propane, so be sure to use the correct fire pit gas pipe size chart.

Gas Feed Pipe Size NG
Natural Gas Feed Pipe Size

Natural Gas Hard Pipe Size Chart

NOTE: The Gas Hard Piping Size For Fire Pits charts above list the specific pipe sizes required for the number of BTUs for new gas line installations. If you are using an existing gas line you must take into consideration the existing gas line capacities to ensure you will have proper pressure. This chart is for reference only, we recommend you consult with a Licensed Plumber/Gas Fitter or NFPA54 (National Fuel Gas Code 72 – current edition) for more details.

Gas Feed Pipe Size LP
Propane Feed Pipe Diameter

Fire Pit Burner Size

Quite often clients look at the dimensions of a fire pit when purchasing a fire pit burner without taking into account BTU ratings. “Bigger is better” in this case is not always best! If you already have the gas piping infrastructure installed, then to achieve a good fire pit flame you must match the burner BTU rating of a burner to the amount of gas and the pressure available at the fire pit location.

Although there are fire pit burners that help achieve a taller flame there is no such thing as a big flame fire pit without a compatible gas supply!

For further reading on this please read the following blog posts.

Flame Height and your Gas Fire Pit – How to get a good flame

How To Successfully Build A Gas Fire Pit Part 1 – Planning