Why don’t Gas Grills use Lava Rock anymore?

This may surprise some of you, but this question still comes up fairly often. From time to time we even see people putting lava rock on top of the heat plates in their gas grills. So do gas grills still need lava rock? Nope! You don’t need lava rock in a gas grill that’s equipped with heat plates. In fact, adding lava rock could damage it.

Why don’t gas grills use lava rock anymore?

That hot surface in a gas grill, above the burners and below the cooking grates, is called the ‘heat plate’ or ‘heat tent’. Most manufacturers name heat plates by combining the word ‘flavor’ and a description of the heat plate’s shape e.g. Flavor -bars, -tents, -plates, and what have you. At Broil King we call them Flav-R-Waves because of their unique, shallow wave shape.

What do heat plates do? They absorb and disperse heat from the burners to evenly heat the cooking surface. Heat plates also protect the burners from drippings and provide a vaporization (or flavor infusion) effect to ensure you get authentic barbecue flavor when grilling on a Broil King gas grill.

How does flavor vaporize and infuse food?

In the beginning, there was fire and meat on a stick. Drippings from the meat fell onto the fire and vaporized into smoky flavor that would rise and stick to the meat. That’s a delicious start if I do say so myself. In the last 75 years, gas grill manufacturers have experimented with a variety of heat media to replicate this vaporization process with varying degrees of success. Let’s take a quick look.

First, there was good old lava rock. These large, porous volcanic rocks were placed above the burners on a rack. They would absorb and radiate heat with the intensity of the burner. They provided adequate surface area to vaporize juices and fairly even heat. However, because lava rocks are porous, they would soak up juices, grease, and other drippings like a sponge, and there was no good way to clean them. They also didn’t protect the burner below and burner rot was a constant issue. The result? They transfer flavors from past meals to future meals in the most unappetizing way. Yummy…

Then there were deluxe ceramic briquettes and several different iterations of them: the pillow style, pyramid-shaped, and honeycomb. They were meant to deliver more even heat than lava rock, better vaporization, and most innovatively they were self-cleaning when hot. Unfortunately, ceramic briquettes were brittle and the ceramic would deteriorate over time. They were easy to break in transit, or upon installation. These manufactured shapes were much more expensive than their lava rock predecessor to create. Briquettes also didn’t solve the burner rot issue since drippings could still rain onto the burner.

On a Broil King history note, we introduced our own Broil King Flav-R-Cast, in the early 90’s. It was a cast-iron plate shaped like pillow ceramic briquettes! It was heavy and delivered amazing vaporization and heat retention but would slowly rust away under the abuse of heat and salty-sugary grill juices. Certainly a unique alternative at the time.

Ultimately, many gas grill manufacturers settled on the very common tent-style burner covers that you see today. They’re made of stainless or porcelain-coated steel and run front to back (they used to run side to side). They create moderately even heat and protect the burner from drippings. Surprisingly most heat tents protect the burner and shear juices away quickly. While the lava rock and ceramic predecessors filled the cookbox side to side and front to back, these new tents didn’t fill the entire cookbox. A lot of the juices that would normally be vaporized dripped straight into the drip tray below.

The Innovative Flav-R-Wave

The stainless steel Flav-R-Wave cooking system maximizes surface area, with just 6mm between plates to completely fill the cookbox. All this extra steel creates a full surface radiant heat bubble at the bottom of the cookbox for more consistent, even infrared grilling.

This is what even heat looks like under a heat camera. The bright spots are intense radiant heat perfect for grilling. The dark spots are basically drainage, juices that fall there are bound for your drip tray and aren’t flavoring your food.

The perfect 32-degree slope of the Flav-R-Wave is like a shallow pitched roof, juices will slowly roll off and vaporize as they roll. A steep pitch heat tent would shear drippings away quickly before they could vaporize into flavor.

What you see in the photo above is vaporization, the flavor that makes grilled food stand out from anything you can cook in the kitchen. It’s smoky and sticky. This vaporization process is largely responsible for creating that delectable and distinct “BBQ” flavor.

Although we left lava rock in the stone age we didn’t forget what its purpose was in your grill. Every gas grill needs that super hot surface to create the perfect grilled flavor and as much of it as possible. The Flav-R-Wave is our current solution for amazing grilled flavor, we’re very excited to see what comes next.

Ben – Culinary Director