Simple Fire Pit hardware

A match lit fire pit (strike a match and turn on the gas) is pretty simple. Starting with the fire ring and working back to the gas supply, you will need a flex connector from the fire ring hub to the ball valve. Another flex connector from the valve to the gas supply stub or LP hose is all you need. Hard piping is an option rather than the flex connectors. Flex connectors are corrugated on the inside. High pressure gas passing over these corrugations can set up a harmonic and the connector may sing. Hard piping does not have this problem, but is much more time consuming and precise to set up. High capacity flex connectors are now out, but I have not heard enough about these as yet to put forth an evaluation.

There are two other hardware pieces you may want to consider. Propane gas does not burn as cleanly as natural gas. Propane produces soot during the burn process. An LP orifice added to the line to the fire ring is designed to add more air to the propane gas mixture. This helps the gas to burn more cleanly.

Thanks to Hearth Products Controls

The fire ring must be supported and a pan may be just what you need. The burner has to rest somewhere. Whatever else you want to add to the pit (ceramic logs, lava rock, fire glass) also needs support. There are two types of pans, the traditional bowl style and the flat pan. Both have a nipple in the center to connect the fire ring. The burner will set down inside the bowl style. You can then add the decorative items on and around the ring.

The flat pan is much cheaper, but lacks the containment ability of the bowl style. It is simply a flat, stainless steel (round or square) piece with a nipple in the center to mount the fire ring.

Photos courtesy of Fire Pit Outfitter.com

These components are 1/2" connections. Larger fire rings like the 36" and above are available in 3/4" sizes. Rings of this size require a much higher gas pressure to get a decent sized flame, 300k BTU and more.

Next blog: A cool fire pit building system

Let's build a basic gas fire pit

42" x 18" match lit fire pit

Where do you start? The fire ring! Good for you. You have already decided on the burner size. That will have a bearing on the pit diameter. Most of the fire pits I have seen are octagon shaped, but square ones, rectangles, and even straight line shapes are common. Take the one above, for instance. The 42 inches is measured flat side to flat side.

There are a couple of things to consider when sizing the pit. Allow at least 4 horizontal inches between the fire ring and the capstones. This will prevent the heat from the flame from discoloring the capstones. If the flame is too close it can even cause the capstones to crack. Translated, that means that for a 24" ring the inner diameter of the capstone opening should be at least 32 inches. The ring should, also, set about four inches below the top edge of the pit to protect the flame from wind.

The pit height depends on taste. Do you see your guests propping their feet on this or maybe leaning on it and placing a cold one on the edge? You might want to consider a larger pit if this will happen while the fire pit is burning. There is nothing wrong with increasing the distance between the burner and the edges of the pit. Height can be excessive, though when sizing the fire pit. There is a point where the fire pit begins to look like a smokestack. That is not all that attractive to me. Again, selecting the height of you fire pit is strictly up to what appeals to you.

Next blog: The hardware

Beautiful fire pit - Disappointing flame

24" stainless steel fire ring

I got a call from a California contractor today. He built a beautiful fire pit, but the client was disappointed with the project. The match lit fire pit uses a 30" fire ring fueled by natural gas, NG. The lighting ceremony produced a 6" flame. The natural gas is delivered to the pit through a one inch pipe. Why is it so wimpy?

"Is there something wrong with the equipment?" he asked.

Unless there is a crimp in the line to the fire ring, restricting gas flow, this is not an equipment problem. The problem is more likely to be a lower than expected gas pressure at the fire pit. Resolving this problem will not be cheap.

The very first decision in fire pit design is 'what will the flame look like?' Once you have that, then the problem of delivering the necessary gas pressure must be solved. Two very important variables must be considered, where will the supply pipe tap be and how long is the run from there to the pit. Once you tap into an existing gas line you cannot create more pressure than is already there. The second consideration is the length of pipe from the supply to the pit. Gas pressure rolls off over distance (see blog of 10/21/8 for more detail).

I suggested to the contractor that he get a qualified plumber to measure the NG pressure at the pit. Pressure of 150k to the ring should produce about a 14 inch flame. That would give a starting point. Since the pit is already built, going to a smaller ring (the smaller the flame the higher the flame) is probably not a viable option.

If he tapped off from the house, he may have move it and tap off from the gas meter instead if the meter is close enough. If he has tapped from the meter, he will have to resize the pipe to the pit. That is an ugly option if the pipe is embedded in the patio cement.

Always, always start with the fire ring (the burner) before anything else. What should it look like? How will the proper amount of gas be delivered to accomplish that look?