The Crossfire ignition system

The Crossfire is a relative new product on the market. Handmade and thoroughly tested, this match lit or remote operated unit is unique. Burners, until now, were simply bent perforated pipes with a central manifold. Gas entering the manifold is distributed throughout the rest of the burner via the cross pieces or spokes. The burners are called fire rings regardless of the burner's shape.

The Crossfire uses a unique port system to produce flame for either natural gas or propane, as you can see in the above photo, Each port is shaped, tuned, and positioned to produce a different overall look. By shaping, tuning and adding additional air to the gas, the manufacturer, Warming Trends, causes the resulting yellow flame to swirl. Standard systems are 24", 30", and 36". Like the traditional electronic ignition kit, the Crossfire is built to be a single unit supported by the pan. The pan itself can also be either flat or bowl style. The pan itself can be ordered with variations in diameter to fit your design. Since pan sizes can vary, the main difference between the three systems are the number of ports. There are five ports in the 24", twelve ports in the 30", and 15 ports in the 36" systems. The maximum gas required for each system is 60k BTU, 108k BTU, and 180k BTU respectively. This is a significant, economic saving when it comes to operating the Crossfires over the electronic ignition systems of 150k BTU for the 24" and the 30", and 300k BTU for the 36".

There is significant heat transfer between the fire ring and the pan and, thus, between the pan and the valve box below for the electronic ignition systems. If the valve box overheats the valve will shut down and the pit flame will go out. Therefore, the warranty on the electronic ignition kits require 18 square inches (36 sq in total) of ventilation on opposite sides of the fire pit below the unit to help dissipated heat. There is very little heat transfer to the Crossfire pan, so ventilation is unnecessary.

The Crossfire has another distinct advantage when it comes to powering the system. The smaller system (the 24 inch) can be run from two D cell batteries. There is no need to run a separate 115 volt electrical circuit. I am told the batteries will last one to two years. I'll accept that it is possible for the batteries to last more than one year, but I can't quite accept two. In any case, just leave enough slack in the flex connector and all you have to do is lift the unit out of the pit, replace the batteries, put the unit back in, rearrange the lava rock, and you are back in business. Cool point #2: The manufacturer will customize a double unit just for you. It is possible to place two systems on one pan and control it from one remote control, and do it from a 120k BTU gas supply. That will give you 10 ports of swirling 18 inch flame in your fire pit.

The Crossfire is a sturdy device to consider when you want remote control of your fire pit ignition. Legend has it that the manufacturer uses a leaf blower to snuff out the flame in order to test the unit's ability to reignite. The Crossfire also comes in a match lit option. You can have the Crossfire's unique flame without having to pay for the sophisticated electronics. This is great for residential use because, usually, the only time the pit will be lit is when the homeowners are actually with it.

For more information about the Crossfire, visit Fire Pit Outfitter.

Photos curtesy of Warming Trends

Next post: Kool furniture!

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.

Propane characteristics and cautions

Liquid propane (LP) is an excellent gas to fire your pit. Propane is trickier and more complex to handle than natural gas. Liquid propane is just that a liquid with a low boiling point. Liquid propane comes in different sized tanks. The tank is not completely filled. This is to allow the liquid propane room to boil off into gas. Larger tanks are able to boil off more liquid propane into gas and can, therefore, flow more propane gas. This is important to know when selecting the fire ring size for your pit. If the control valve flows more gas than the tank can process the tank will shut down to about 10% flow.

My thanks to Propane 101. Check out this website for much more information about propane.


SPECIAL ANNOUNCEMENT

I just heard last week of a propane fueled fire pit blowing up. Fire glass, the fire ring, and the pan were ejected out the top of the fire pit. Luckily, no one was injured. I have not heard of this happening before, but that is not to say it hasn't. As mentioned earlier, propane is heavier than natural gas. Somehow propane gas seeped down into the bottom of the pit and then ignited. It seems to me that the gas would have had to flow for a longer time than it normally takes to ignite the burner. Another possibility is that liquid propane got into the supply hose somehow. This condition will produce much more propane gas than what is produced in the tank. Now, this is only speculation on my part, but it does emphasize the fact that LP must be treated with caution and respect.

I would like to see your comments and experiences with fire pits, NG or LP, that have ignited in an uncommon way.

One other item, LP tends to cause soot as it burns. It is just not as clean burning as natural gas. An LP orifice added to the line to the burner introduces more air to the mixture going to the fire ring and helps to minimize this problem.

Next blog: Beautiful fire pit - Disappointing flame

Gas - NG or LP and how much?

Now that you understand what to expect from different sizes of fire rings, the next thing to consider is that which makes a burning ring something to behold, the gas. Gas fire pits are fueled by natural gas NG or liquid propane LP. The available gas determines the quality of the burner flame. Imagine putting time and money into a beautiful fire pit of your own design. You light it and it produces a 1 inch flame. What the hell happened?

Natural gas and liquid propane have their unique problems when applied to a fire pit. First of all for both, gas pressure rolls off over distance. Tapping into an existing smaller pipe with a larger pipe will not increase pressure. I strongly recommend using the services of a qualified plumber to assist in determining how to pipe the gas to the pit, and how much gas (in BTUs) to expect at that point. Someone qualified to measure gas pressure at the fire pit will save you much disappointment and expense later.

Let's start with natural gas for more detail. The most convenient source of natural gas for your home fire pit is the nearest line in the house. The problem with that is you are stuck with whatever pressure there is in that pipe. The architect may have designed the gas capacity to the house based on the expected usage. For instance, the architect may have sized the supply pipe from the meter to support the furnace, the water heater, and the kitchen stove. As I mentioned before, 150,000 BTU is an excellent pressure level for 18" and 24" fire rings. You may find there is considerably less in the pipe you plan to tap into. If you find that is indeed the case, the resolution is to run a line from the gas meter directly to the pit. Your plumber should be able to to select a pipe size that will deliver the quantity of gas necessary to run the pit for the desired burn.

Next post: "Let's talk propane"

Where to start when designing a gas fire pit

Build a fire pit (firepit)

It is my experience that many people building gas (natural gas NG or liquid propane LP) fire pits start at the end of the process and work backwards and are often disappointed with the results. Fire pit design must start with the fire ring (the burner). The final size and height of the pit depends on the proper selection of this one component. Fire rings generally come in 6 inch increments starting at 6 inches up to 48 inches. Burners are custom made above 48 inches. The rings are made of either black iron or stainless steel. Black iron is more susceptible to corrosion than stainless steel, but should still be serviceable for 2 to 4 years depending on the climate. Compare Seattle, Washington to Flagstaff, Arizona, for instance.

First Rule: The bigger the fire ring the shorter the flame at the same gas pressure. An 18 inch ring will have a 22-24 inch flame at 150,000 BTU at the pit. A 24 inch ring will produce a flame about 18 inches tall at the same pressure.

The fire ring affects the design of the pit because of space and offset distance requirements. More about this later in a separate blog entry.

Next blog "Got gas?"