Match lit is not the only way to fire the ring

The match lit method of igniting a gas fire pit fire ring is just what it sounds like.  Strike a match (better to use the longer grill lighters to increase the distance between your hand the igniting flame) and turn on the gas.  As discussed in the last blog, there some drawbacks to a match lit gas fire pit.  The most important is the lack of a flame control failsafe.  If an unattended gas fire pit flame goes out, there is nothing to cut the gas flow.  Gas has not fulfilled its destiny until it becomes flame.  Therefore, gas will seek an ignition agent, like that cigarette in someone’s hand, to become greater than itself.

In its simplest form, a flame failsafe is a valve and a sensor.  The sensor tip sets in the burner flame giving assurance to the valve that the gas is, indeed, burning.  Should the flame go out, the sensor quickly cools and signals the valve, “Hey!  Got gas.  Don’t got flame.  Shut down.”

Match lit gas fire pits are just fine for residential applications.  People generally don’t light the fire pit unless they intend to enjoy the warm spectacle.  Come on.  We’re turning money into fire here.  My father would get on us kids for leaving the TV on when no one was in the room.  “The furniture doesn’t need to be entertained.”  Same idea.

Flame control for public applications is an absolute must for liability reasons.  The cost to a hotel, spa, or golf course to pay to station someone at the fire pit for the burn duration is much more than building the fire pit using a failsafe system.  Ignition is either by using a hand held remote control or a wall switch.  Remote controls tend to walk off by themselves.  A wall switch works much better for public uses.  Unless a fire pit is intended to be on all the time, I suggest adding a timer to the wall switch.  This will help keep costs of operating the fire pit down and diminish the need for constant surveillance by paid personnel.

The alternatives to the match lit system are: battery powered, push button grill, electronic ignition kits, and Crossfire.

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

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?