OnlyFire Pizza Oven Kit Review

I’ve cooked pizza in many different appliances both indoors and out, with gas, wood, and electricity. I’ve even made pizza directly on the grill, which is an…OK method. So when I got the opportunity to test the OnlyFire Pizza Oven Kit, I was ready. This device is a true pizza oven, but its power comes from a standard gas grill rather than any onboard heating. It comes with a pizza stone, peel, thermometer, and oven enclosure that sit on top of the grill grates and heat up to extra-hot pizza-baking temperatures. Between home and Lab testing, lots of dough and toppings have been put into the maw of this oven. After eating plenty of pizza, I have opinions.

The OnlyFire arrives pretty much ready to go; you can pull the pizza stone and stainless steel oven chamber out of the box and put them right on the grill. The only bit of assembly you have to do is to screw the peel onto its handle, but that caused me a bit of trouble. The holes in the wooden handle weren’t drilled cleanly through and were partially obstructed. I tried to just muscle it but couldn’t get the screws to catch; I had to clean out the holes and screw threads to put the thing together. While it’s not an earthshaking problem, it’s definitely something that slipped past quality control.

The metal peel itself also has sharp edges that could slice a finger or hand, so you’ll need to be careful—you might even want to file or sand them. The instructions say “metal edges can be hazardous,” but I didn’t expect the peel to be this worrisome.

Actually using the OnlyFire is quite easy. It’s essentially a low-slung stainless steel box with a holder at the bottom for the pizza stone that puts it directly in contact with the grill grates. There are flip-up side handles to carry the whole contraption, and its light weight makes it easy to get on and off of the grill. (You will, of course, need grill gloves or oven mitts once the gas is turned on.)

There’s a good-sized opening in the front to watch the pie’s progress, with room to turn and move it with the peel. Its long handle is helpful in manipulating pizzas, though I did have to “choke up” a bit and hold it in the middle with topping-heavy pies. If you have trouble, the door can flip up to make a larger, more accessible opening, too. There’s also a helpful thermometer integrated into the front door to monitor the interior temperature.

Thanks to the dense stone and the oven body that holds in heat, the OnlyFire is able to achieve some pretty impressive temperatures, which is key for good results. After just 15 minutes of preheating, it gave a top reading of 760 degrees on the sides of the oven, with the front and back staying consistently in the 600s. That’s not quite as hot at the brick oven at your local Neapolitan pizzeria, but it’s much better than a standard oven can do—and much better than a grill can do by itself.

Unfortunately, there were a few construction flaws in the unit I received. There were gaps on both sides of the door where they should have been flush to the body, which could potentially let in more air than intended. The bottom of the oven also didn’t quite sit flat on the grates, wobbling a bit when I went to adjust the pizza. That said, neither of these issues seemed to affect the OnlyFire’s performance very much.

The kit featured here is 17 inches square and made specifically for gas grills. It fit into my large Weber grill without any problems and should work with all but the smallest models, but you should definitely measure your grill before you order one just to be sure. (If you’re a charcoal griller, OnlyFire makes a larger oven kit designed for kettle grills.)

Despite the unusual cooking method, the OnlyFire produced great pizzas. Both the toppings-heavy supreme and denser whole-wheat-crust pies tested in the Lab came out nicely, with fairly even doneness and good browning. They took a bit longer than the super-hot dedicated pizza ovens tested in the Lab, but a minute or two shouldn’t make very much difference in your dinner routine.

The problem with cooking pizzas on a grill is that since the heat comes entirely from below, they tend to cook faster on the bottom than on the top. The OnlyFire oven body helps retain heat to brown cheese and toppings, but every time you open the lid to turn or move the pie, the temperature drops precipitously. No matter what type of pizza I cooked, and no matter how thick the dough was or how many toppings I had, the bottom of the pizza almost always cooked faster than the top. There was also a difference in temperature from the front of the oven to the back, though turning the pizza occasionally helps solve that problem.

One technique that helped ensure more even doneness was closing the lid of the grill itself. The OnlyFire’s instructions say to leave the grill lid open as closing it can damage the integrated thermometer, but after a few mediocre test pizzas, I decided I didn’t care. Closing the lid helped cook the top of the pizzas more evenly, and the thermometer is working just fine so far. (Plus, there are lots of wireless grill thermometers or instant-read units that can give you a quicker and more accurate result if that’s what you’re looking for.)

There’s a fairly steep learning curve with the OnlyFire. It took me several pies to figure out the technique, and every time I cook a new one I get a little bit better at the timing. If you turn the pizza too often the oven cools down and undercooks it, and if you leave it too long parts of the crust can start to burn. But the truth is that this is the case with any sort of oven: There’s an art to baking pizza, and it simply takes practice to perfect.

Besides cooking pizza, you can also use the OnlyFire as a general high-temperature oven/broiler. I threw a pan of broccoli and peppers in it, and they came out nicely charred. It’s hot enough to sear steaks or meaty fish like tuna, too. You could also use the stone by itself in a standard oven or on the grill.

When it comes to cleanup, there’s pretty much nothing to do with the OnlyFire. Anything stuck to the stone or interior of the oven should burn off while preheating for the next use, and if the stone gets really dirty you can simply flip it over and use the cleaner side. If you ever end up with any extensive buildup, you can also scrape down the stone with a metal spatula or even just a ball of aluminum foil. You can rinse the stone under water if necessary, but you should never use soap. Also, make sure not to get the stone wet while it’s still hot or heat up a wet stone before it’s dried completely. Either of these can cause cracking. (If you do need to replace your OnlyFire stone, you’ll have to buy a complete tool set that also includes a peel, spatula, and pizza cutter.)

At well over $100 for a piece of steel and stone that you need your own grill to even use, this oven feels expensive, but when you compare it to other dedicated pizza ovens—which can run well into the thousands of dollars—it’s not a bad deal. If you’re a pizza lover who already has a grill, the OnlyFire will get you much better results than your home oven or grill can on their own and at a relatively low price.

OnlyFire vs. Ooni

In the overall testing of pizza ovens, Ooni made a great showing. The cult-favorite brand makes several models of self-contained pizza oven, and its gas-powered Ooni Koda 12 was our top choice. The wood-fired Fyra 12 and gas or wood Karu 12 were close behind, and the recently released Volt 12 uses electricity for an indoor oven with similar abilities.

Compared to the OnlyFire, the Ooni models cooked pizza more evenly, at higher temperatures, and much more quickly (in as little as a single minute). With the Koda in particular, you don’t have to worry about starting or managing a wood fire, either. But it costs more than twice as much as the OnlyFire, doesn’t include a peel, and is smaller in capacity. No matter which pizza oven you choose, there’s going to be a learning curve; pizza is just one of the more difficult dishes to master under any circumstances.