The Flame Boss 300 Wifi
Temperature Controller


Connections

All the connections are on the bottom edge of the system unit. The following photo shows (from left to right) the power plug, the blower plug, the pit temperature probe plug and the meat temperature probe plug:


Temperature Probes

The Flame Boss controllers come with two temperature probes, one for the pit and one for the meat. Previously, the temperature probe cables were clad with PTFE which helps to prevent kinking and promotes tidy coiling of the cables. These PTFE-clad probes were good up to about 450-500°F. We did manage to damage the coating on one of our pit probes through carelessness, but now Flame Boss has added some new high temperature probes without the PTFE that should be good up to about 575°F. Flame Boss 300 controllers ship with the high temperature probes.

Unlike the majority of controllers on the market, Flame Boss probes are not thermocouples. They are platinum RTD sensors. What's that? Well, if you don't want to know skip the next 3 paragraphs.

First of all, a thermocouple works on the Seebeck effect. When two ends of a conductor (wire) are at different temperatures, a voltage is created between the two ends. The magnitude of the voltage depends on the temperature difference between the two ends. The magnitude of the voltage also depends on the metal that the wire is made from. If you take two conductors made from different materials, there will be a different voltage created in each conductor. Different types of wire will thus generate different voltages for the same temperature difference. Then if you connect the two conductors at one end, the two voltages will add producing a voltage across the two conductors that varies with temperature. With me? If you know the materials, then you know the voltage generated for each temperature and this then gives you the DIFFERENCE in temperature between the two ends of the pair of conductors. Finally, you put a thermistor inside the meter that the probe plugs into to tell you the temperature of that end of the pair of conductors. Voila! You know the temperature of one end of the pair of wires, and you know the temperature difference between the two ends. Therefore you know the temperature of the other end! Simple, eh?

Well, platinum RTD sensors work like this. Many materials have an electrical resistance that varies with temperature. So if you can measure the resistance, you know the temperature. Platinum is a popular material for this type of sensor. You pass a small current through the sensor, measure the resistance and deduce the temperature.

What's the difference? Thermocouples are faster reacting and can measure much larger temperature ranges. RTD sensors are more accurate and more stable. Why choose RTD sensors over thermocouples? It turns out that an RTD sensor does not need to be calibrated to the unit which simplifies things a bit. The slower response time is not a critical factor in this application and the RTD sensor is more accurate, so RTD sensors are a reasonable choice.

Still with us? Good. One note of warning before we proceed. The plugs used on these probes are the same as the plugs used on probes made by at least one other manufacturer of temperature controllers. Thermocouples and RTD probes are not plug compatible, so just because the plug looks the same, don't be tempted to use the probes from another manufacturer.

So, as we previously explained, Flame Boss has two types of temperature probes available now. Here are photos of the older style temperature probes with the PTFE cladding:


And here are photos of the new style high temperature probes without the PTFE cladding:


The probes are made from stainless steel and as we just explained contain a platinum RTD sensor.

The older cables have stainless steel armor braid that is coated with PTFE and can withstand temperatures up to 500°. What is PTFE? Well, scientists know it as Polytetrafluoroethylene. We mere mortals know it as Teflon®. Be careful not to kink the wire. The junction where the cables enter the probes appears not to be sealed, so avoid getting this junction wet.

The newer high temperature probes have just the stainless steel armor braid and should withstand temperaturees up to 575°F. Again, be careful not to kink the cables and it is probably wise to protect any junctions between cables and probes from moisture.

The probe and the wire should be shielded from direct radiation from a hot fire. Do not let it come into direct contact with flames. If you need to shield the wire, you can place a layer of aluminum foil beneath it. Also, having the pit probe itself exposed to direct radiant heat can cause it to register a temperature which is higher than the air temperature in the cooker, and thus fool the controller into cutting back on the fire. (If a probe does fail, you will be able to tell because when plugged into the controller with no heat applied to the probe, the controller display will show three dashes instead of a numeric value.)

An alligator clip is provided with the pit probe which you can use to clip the probe to your dome thermometer or the food grid, as you see fit.

Which style probe is better? Well, for our money, if you are careful with your probes, the PTFE coated cables make coiling and uncoiling the cables a cinch. If you want protection from higher temperatures, well then of course the new high temperature probes are what you want.


New Support For Multiple Temperature Probes

Probably the major functionality improvement provided by the Flame Boss 300 over previous models is the ability to add up to two additional food temperature probes to the mix. This is accomplished via the use of optional y-cables that plug into the existing Pit and Meat temperature sockets on the system unit. Using two y-cables, you now have four sockets for temperature probes. All Flame Boss temperature probes appear to work with the y-cables as we used one of the original Flame Boss 100 probes and it was recognized. y-cables and additional food probes can be purchased separately from Flame Boss.

Here is a photo of one of these y-cables. Note that one wire is labeled "M2/M3". The photo doesn't show it, but the other wire is labeled "Pit/M1". This will help you figure out which probe is which when you hook them up to the controller.


Here's a handy dandy graphic to help you figure out which probe goes where if you use one of the four possible configurations of y-cables:


It is worth noting that you can plug and unplug the food and pit probes at any time without having to cycle power on the unit. The probes will simply appear and disappear from the display when you plug and unplug them.

When you do hook up multiple food probes to the unit, you will find that the main display, instead of showing a value for "MEAT1", will start scrolling through however many food probes you have attached. Here is what it looks like with all three food probes attached:


One final consideration is that there has now been added to the meat alarm menu item the ability to set separate alarms for each food probe. You can set the alarms whether or not the probes are actually attached.


Temperature Probe Accuracy

How accurate are the probes? We measured the temperature of boiling water using the Flame Boss controllers. Using our boiling point calculator to determine the boiling point of water, the Flame boss 300 controller got the measurement within 1.5°F.


Calibration

As we previously explained, RTD sensors require no calibration, so there is no calibration procedure.


The Blower

Now let's take a look at the blower. The blower for the Flame Boss 300 is unchanged from previous models. Hence we'll just repeat our commentary from our previous review.

Here are photos of the blower and the adapter:


The Flame Boss blower is rated at 6.5 CFM which is definitely adequate for most home-sized cookers. It has no built in damper. Also, the connection between the blower and the adapter is not airtight. The blower is merely inserted into the hole in the adapter and a tab on the blower housing keeps the blower from falling out of the adapter. Together these two factors allow a lot of air to enter the cooker even when the blower is not activated. It also makes the blower susceptible to wind forcing more air into the cooker. We'll see later how this affects the unit's ability to control the temperature of the cooker at low temperatures.


One last note about the blower. The Flame Boss units are plug-compatible with BBQ Guru blowers. If you have a BBQ Guru controller and wish to move to a Flame Boss (say, for example to upgrade from a non-wifi unit to the Flame Boss 200 or 300 Wifi unit) you can buy a Flame Boss system unit by itself and use the BBQ Guru blower instead of purchasing the Flame Boss blower. Also if you find you want an upgrade over the Flame Boss blower after you purchase your unit, you could buy a BBQ Guru blower to replace it. (This is actually the configuration that we use for all our charcoal testing now.) The BBQ Guru blower can run at variable speeds, just like the Flame Boss blower, so your Flame Boss controller can take full advantage of having a variable speed blower.


Update (08/26/17): Flame Boss recently released an upgraded blower which addresses the issue of wind entering the air intake and making it difficult to maintain temperature. View our special report in which we test the new blower.

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