is supported by our Pitmaster Club. Also, when you buy with links on our site we may earn a finder’s fee. Click to see how we test and review products.

Flame Boss FB400 Wi-Fi Review

Share on:
Flame Boss FB400 Wi-Fi Review
The Flame Boss 400 Wi-Fi is a thermostatic controller designed to regulate the temperature of a charcoal-fired cooker like the Big Green Egg or the Weber Smokey Mountain. It works in conjunction with a free Android or iOS app or on the company’s website via any browser. It is easy to install and provides excellent temperature control.
The unit comes with a manifold to attach the blower to the cooker’s lower vent. There is also a fitting for attaching the unit to a cooker with a threaded coupling. Intallation took only a couple of minutes and didn’t require any tools.
Two temperature probes are included, one for the cooker temperature and one for the food. The former provides feedback about the internal temperature of the cooker. The cooker temperature is compared to the target temperature set by the user. If the cooker temperature is below the desired value, the Flame Boss controller increases the power to the fan, increasing airflow. Increased airflow raises the temperature. Similarly, if the cooker temp is too high, the airflow is reduced, and temperatures will drop. The trick with controllers like this is compensating for the lag between increased airflow and increased temperature. If the controller doesn’t add or subtract airflow in the right amounts, the temperature can fluctuate wildly. This controller was very well behaved.
I conducted this test while cooking some ribs on a cool day (60°F, 13°C) with no wind on an 18.5 inch Weber Smokey Mountain. I filled the fuel tray about half full with Kingsford charcoal briquets and lit about a half chimney of the same fuel. Once the briquets in the chimney were covered with ash, I poured them on top of the unlit charcoal, added some hickory and assembled the smoker. After the temp rose to my setting of 225°F, I removed the cover and put the ribs on the upper grate. I placed the temperature sensing probe about 2-3 inches from the food. I did not use a probe to track the meat temperature. Here is a graph of the temperature vs. time. (Click on image to enlarge.)
Plot of Temperature vs. Time
The temperature dip just before noon was the result of removing the cover to add the food. The controller sensed the rapid drop in temperature, alerted me that the cover had apparently been removed, and correctly delayed powering up the fan. After a minute or so, the controller resumed fan control and the temperature stabilized at my setting of 225°F. For the next two hours, the temperature barely fluctuated. After a couple of hours, the build-up of ash on the coals caused the temperature to begin to oscillate a bit, so I jostled the fuel and the temp settled back down. As you can see from the graph, the fan output was only a small percentage of its capacity, suggesting that the unit could maintain temperature in much colder conditions. The temperature regulation is the best that I have observed to date.
The 400 Wi-Fi has no controls or display on the hardware itself; it must be controlled from a phone, tablet or web browser. It communicates with the cloud via the user’s home router, making its control functions and readouts accessible anywhere an Internet connection is available. Once the unit is set up with the SSID and password of the router, it will connect automatically when powered up. It remembers previous settings, so you could just plug it in and start cooking. If you are using the meat thermometer, you can specify at what temperature the app will announce that the food is done, and when that temp is reached, you can set it to reduce the cooker temperature to keep the food warm. The website mentions that you can set a timer, but I couldn’t figure out how to do that. Aside from audible/visible notifications generated by the app, you can also set up e-mail notifications if the cooker’s temp goes outside the limits you set or when the food is done.
I ran this test using an optional battery pack (YB1204500-USB) that can power the unit without the AC adapter. Its nameplate rating is 4500mAh at 12V or 9000mAh at 5V. It has five tiny LEDs that indicate its state of charge. I charged the battery fully before I began. After nearly five hours of use, including supplying power to another thermometer I used for data collection purposes, it still showed four lit LEDs, so the capacity should be more than adequate for even the longest cooks.
The Flame Boss 400 Wi-Fi has only one food probe, but that is probably not a deal breaker for most cooks. The documentation for the app is on the sparse side – apparently we’re supposed to be able to figure it all out by ourselves. I like that I can access and control the unit via a web browser. From the website, you can also download the raw data – time, temperature and fan data – but the data’s units are not specified. I had the target temp set at 225°F but the downloaded data showed 1072, and the fan’s numbers are similarly cryptic. Unless you plan to plot the data using Excel, this probably isn’t a big deal.
Setup is easy and the temperature control is excellent. The app has the basic functionality needed to control your cooking session, and the data is retained in the cloud. One minor glitch – and I do mean minor – is that the unit will not reconnect with the router if the router is shut off and then turned back on. You have to power down the controller and then power it back up to re-establish communication. The price is lower than most of its competitors and the quality of the unit and the temperature probes is good. Overall, this unit gets a Gold Medal for ease of use and performance.
  • Thermometer Function:
    Thermostats/Temperature Controllers
  • Item Price:
    $ 219.00
  • Where to buy (buying from this supplier supports this website):
  • Probe:
    Food: length: 3.75" (95mm), diameter: 0.127" (3.2mm), cable: 72" (1.8m); Cooker: alligator clip, cable:
  • Battery Type:
    AC adapter, optional battery
  • Battery Life:
    Not specified
  • Safe Operating Range:
    Not Specified
  • Min & Max Temp:
    Not Specified
  • Display Precision:
  • Actual Temp at 130 Degrees:
  • Actual Temp at 225 Degrees:
  • Actual Temp at 325 Degrees:
  • Speed from 32 to 212 Degrees:
  • Numbers Display Size:
  • Water Resistance Rating:
    Not Specified
  • Weight:
    0.45 lb. (204g)
  • C/F Switch:
    No CF swich
  • Backlight:
    No Backlight
  • Color Options:
  • Thermometer Connection:
  • App:
    iOS and Android and Web browser
  • Logging:
    In cloud
  • Included:
    Controller, 2 probes, universal adapter, power supply, minimal instructions
  • Available Accessories:
    Optional battery pack
  • Alarms:

Published On: 11/12/2018 Last Modified: 2/9/2022

  • Bill McGrath - Bill McGrath is's Thermometer Maven. He has sophisticated equipment, an electrical engineering degree from Cornell University, and an MBA (almost) from UC Berkeley. Despite being mostly retired, he is still the person responsible for developing and updating all of ExxonMobil's training modules.


High quality websites are expensive to run. If you help us, we’ll pay you back bigtime with an ad-free experience and a lot of freebies!

Millions come to every month for high quality tested recipes, tips on technique, science, mythbusting, product reviews, and inspiration. But it is expensive to run a website with more than 2,000 pages and we don’t have a big corporate partner to subsidize us.

Our most important source of sustenance is people who join our Pitmaster Club. But please don’t think of it as a donation. Members get MANY great benefits. We block all third-party ads, we give members free ebooks, magazines, interviews, webinars, more recipes, a monthly sweepstakes with prizes worth up to $2,000, discounts on products, and best of all a community of like-minded cooks free of flame wars. Click below to see all the benefits, take a free 30 day trial, and help keep this site alive.

Post comments and questions below


1) Please try the search box at the top of every page before you ask for help.

2) Try to post your question to the appropriate page.

3) Tell us everything we need to know to help such as the type of cooker and thermometer. Dial thermometers are often off by as much as 50°F so if you are not using a good digital thermometer we probably can’t help you with time and temp questions. Please read this article about thermometers.

4) If you are a member of the Pitmaster Club, your comments login is probably different.

5) Posts with links in them may not appear immediately.



Click for comments...


These are not ads or paid placements. These are some of our favorite tools and toys.

These are products we have tested, won our top awards, and are highly recommend. Click here to read how we test, about our medals, and what they mean.

Use Our Links To Help Keep Us Alive

A big part of this site is our unbiased equipment and product reviews. We love playing with toys and we have no problem calling them the way we see them. Some companies pay a finder’s fee if a reader clicks a link on and buys a product. It has zero impact on our reviews, zero impact on the price you pay, and the sites never tell us what you bought, but it has a major impact on our ability to keep this site alive! So before you buy, please click our links. Here’s a link that takes you to a page on Amazon that has some of our favorite tools and toys:

The Good-One Is A Superb Grill And A Superb Smoker All In One

The Good-One Open Range is dramatically different from a traditional offset smoker. By placing the heat source behind and under the smokebox instead of off to the side, Open Range produces even temperature from left to right, something almost impossible to achieve with a standard barrel shaped offset.

Click here to read our complete review

Groundbreaking Hybrid Thermometer!

Thermapen One Instant Read Thermometer

The FireBoard Spark is a hybrid combining instant-read capability, a cabled temperature probe, Bluetooth and Wi-Fi connectivity. We gave Spark a Platinum Medal for pushing the envelope of product capability while maintaining high standards of design and workmanship.

Click here to read our comprehensive Platinum Medal review

The Cool Kettle With The Hinged Hood We Always Wanted

Napoleon’s 22″ Pro Cart Charcoal Kettle Grill puts a few spins on the familiar kettle design. In fact, the hinged lid with a handle on the front, spins in a rotary motion 180 degrees. It’s hard to beat a Weber kettle, but Napoleon holds its own and adds some unique features to make the 22″ Pro Cart a viable alternative.

Click here for more about what makes this grill special

Is This Superb Charcoal Grill A Kamado Killer?

The PK-360, with 360 square inches of cooking space, this rust free, cast aluminum charcoal grill is durable and easy to use. Four-way venting means it’s easy to set up for two zone cooking with more control than single vent Kamado grills. It is beautifully designed, completely portable, and much easier to set up for 2-zone cooking than any round kamado.

Click here to read our detailed review of the PK 360

Click here to order directly and get an exclusive deal

Surely you know somebody who loves outdoor cooking who deserves a gift for the holidays, birthday, anniversary, or just for being wonderful. There he is, right in the mirror! Here are our selections of best ideas, all Platinum or Gold Medalists, listed by price.

Click here to see our list of Gold Medal Gifts

The Efficiency Of A Kamado Plus The Flexibility Of The Slow ‘N Sear Insert

kamado grill
Built around SnS Grill’s patented Slow ‘N Sear charcoal kettle accessory, this 22-inch kamado is a premium ceramic grill that brings true 2-zone cooking to a kamado.

Click here for our article on this exciting cooker

Our Favorite Backyard Smoker

The amazing Karubecue is the most innovative smoker in the world. The quality of meat from this machine is astonishing. At its crux is a patented firebox that burns logs above the cooking chamber and sucks heat and extremely clean blue smoke into the thermostat controlled oven. It is our favorite smoker, period.
Click here for our review of this superb smoker