We occasionally hear complaints about how our Pro-Series® or Type-K probes burn out in BBQ smokers. For example, “How can a probe rated to 640°F burn out in a low-and-slow smoker that is running at 275°F?!?” It’s a fair question, and today we hope to answer it.
The most important—and maybe the most secretly-obvious—fact to remember is that smoke comes from fire, and fire is much hotter than 275°F (135°C). When wood burns, it does so at temperatures in excess of 1,100°F (593°C), hot enough to burn out either the sensor or the cable insulation on a probe. To guarantee that your probes have their maximum life expectancy, careful thought about how they interact with the smoker must be taken.
Given that fire is needed to make smoke and fire is too hot to cook food slowly, most BBQ cookers and grills use various systems to diffuse the heat and insulate your food from burning. Whether it’s a water dish, a ceramic plate, or just a physical displacement of the fire, they all have ways of making smoke without exposing your food directly to fire. That’s good news for your pork butt, but it can be bad news for your thermometer probes! It’s easy to think that just because your meat is cooking safely that your probes are safe, too, but that’s not always true.
Now, before we go forward, we should say that probes just can’t last forever. Because of the harsh conditions in which they operate, they will eventually fail. But ThermoWorks probes do have the longest life and highest durability in the industry. Our probes are second to none! Not only do we use extremely accurate sensors, but we incorporate many features that help to prolong the life and usability of our probes. The spring-supported transitions prevent kinking at a crucial point. Our tough, stainless steel over-braid protects the cable from damage and provides premium heat resistance and high heat tolerances. So while we cannot guarantee our probes for years and years, you can rest assured that they will outlast and outperform their competitors. Still, if you have a big cook coming up, it’s a good idea to keep a few extra probes on hand. They’re not very expensive and having some extras could save you a lot of trouble.
Common probe mistakes
In our experience, there are a few common mistakes people make that cause probe failure. By learning about them, you can avoid them and prolong your probe’s life.
1) Threading through the chimney
In an attempt to keep their cables from kinking, some people thread their probe cables through the chimney or exhaust vent of their cooker. While the intention is a good one, the method is not. Yes, your main smoker chamber may be running at 275°F (135°C) while the heat is diffused throughout the cooker. But as it comes up the chimney, that heat is collected and concentrated so that exhaust temperatures are higher than the cooking temp. They can, in fact, be hotter than your cable’s heat rating. You can quickly burn out your cable this way.
The solution here is to not use the chimney. Most smokers have some kind of grommet, port, or cut-out that is intended for probe cables. Use it! And if your smoker doesn’t have such a port or you don’t feel comfortable creating your own, it’s actually better to simply close the smoker lid on your probe cables than to thread them down through the hot chimney.
2) Placing cables over hot spots
As we’ve noted already, there must be fire to make smoke, and even the smoldering of the woodchips is over 1,000°F. Despite the systems of diffusers and baffles that are meant to protect your meat from the high heat, there are places in the smoker where that heat is accessible. Every smoker has hot spots, and a good pitmaster will know not only where those spots are, but how to use them and how to avoid them.
Because of the variety of smokers, it may be instructive to take a look at a few common smoker types to learn about hot spots and how to avoid them.
Most pellet smokers have a drip tray that acts as the main heat diffuser. The fire burns underneath the tray, and the tray itself heats up, acting as a radiant heater for the meat. However, some of the heat from the fire also comes up around the sides of the tray. On some models, the tray can be moved, and it’s best to move it as close to the front as possible so that if you need to run your cables through the lid you won’t be crossing a hot zone.
Egg-type or ceramic smokers
These smokers use ceramic diffuser plates that absorb and slowly radiate the searing heat from the coals. The three-legged design, however, creates ample opportunity for probe cable destruction. If you don’t run your cables into your smoker over one of the three legs, you expose the cable to temperatures that easily surpass their temperature ratings. Make sure you are crossing a ceramic bridge when you are setting up your probes.
Offset smokers have a firebox on one side, with all the heat entering the smoker from a small opening at the junction of the firebox and the smoking chamber. The area closest to that opening is the hottest place in the smoker. When you run your cables into your offset smoker, do so starting on the side furthest from the firebox. While the average temperature in another part of the cooker may be low, the intense heat coming from the firebox can definitely damage your probes.
The hot spots in your kettle-type smoker will vary widely, depending on their design and your arrangement of coals. Be aware of where the fire is, where the direct heat is traveling, and where your cables are.
Also, a common problem for kettle grill smokers is kinking in the lid. To keep the smoke and heat in, people will press the lid down hard over the cables, sometimes kinking them. If your kettle has a hole or grommet port for probe cables, be sure to use it!
3) Placing the transition over the water pan
In some cookers, especially the Big Green Egg type, a water pan can be placed over the fire to act as a diffuser This provides the added benefit of steam produced in the water pan which helps to transfer heat more efficiently to the meat. But if you aren’t careful with your probe placement, the water pan can be a hazard. If the probe transition extends out over the water pan, the hot steam that is produced can penetrate the otherwise water-resistant seal and condense inside the probe, causing it to short out.
To prevent this, avoid inserting your probe laterally into the meat. When you insert the probe from above, instead, the mass of the meat itself can baffle the steam so that it doesn’t penetrate the probe transition. This isn’t really an option for some cooks like a whole turkey, which really should be probed laterally, but for most smoking projects, try to insert the probe from above.
Note: Because of the nature of the two technologies, this is really only a problem for the Pro-series thermistor probes, not the Type-K probes. If you have a water smoker or often cook with a lot of steam, it may be best to invest in Type-K technologies.
4) Laying cables across grates
One of the easiest mistakes to make when handling your probes is allowing the cable to rest on the grates of the smoker or, even worse, droop down below the grates. Why is this a problem? Because the grates are, well, great conductors of heat. As we’ve already discussed, every smoker has hot spots where the heat from the fire is more direct, despite all the diffusion plates and baffles. The metal in the grates can channel that heat more directly than the surrounding air, meaning that while the probe itself is tucked safely in your brisket, the cable might be draped across a grate that is 700°F (371°C).
Likewise, if your cable droops down below the grate, you can greatly increase the chances that it will encounter hotter temperatures. Heat propagates by what we call the “inverse-square law,” meaning that if you double the distance from the heat source, you cut the intensity to a fourth—triple the distance and the intensity drops to a ninth. Conversely, if you halve the distance to the heat source, you increase the intensity of the heat by four times. A cable that droops down below the grates may be experiencing much higher temperatures.
In an associated probe failure, people sometimes let their cables rest on top of or against the sides of the smoker. Again, though the air inside the smoker may only be at 275°F (135°C), the metal on the sides or top of the smoker may be much hotter.
When you feed your probe cable into your smoker, be sure there is enough tension in the cable to keep it from drooping. If there is not enough tension when you run your cables through your grommet or cable port or lid, you may need to move your thermometer further away from it to create very light tension. You don’t want to stretch the cable so hard that you pull on the transition spring, but be sure that any loose cables do not drape themselves against the side of the smoke chamber.
Sometimes when people turn their meat they’ll pull the probe out and, without thinking, set the probe on the grates where not only can the cable get too hot, but the probe tip itself can drop below the grate into the hot zone. When you remove the probes from the meat, be careful to remove them from the smoker.
Some other helpful tips
Some people use foil to help protect their probes, wrapping the cable to protect it from hot spots. This is an excellent idea, but it must be done correctly. If your cable must cross a hot zone, wrap the section over the hot zone in a ball of foil that doesn’t extend beyond the hot part. Wrapping the entire length of the cable in foil can actually channel hot air down the foil tube of foil to the transition. Use foil to wrap where needed, but only where needed.
Kinking and storage
If a cable becomes severely kinked, it can break the wires inside, causing a short and probe failure.
To prevent kinks from happening, be careful how you spool and unspool the cable. Much like a garden hose, if you pull a cable taut from a coiled position, it will kink. Also, when you go to store your cables, coil them loosely around your hand, not tightly around your thermometer. The kind of tension you apply when wrapping a cable tightly can actually damage the wires inside.
It’s a fact of life. All smokers have flare-ups—even pellet smokers. Improper cleaning can cause an accumulation of flammable material inside any smoker, leading to unexpected fires. Non-mechanical smokers are prone to flare-ups from dripping fats. All it takes is one tongue of flame rising above the grate surface to burn out a probe. So keeping your smoker clean can help you extend the life of your probes.
Pulling on the cables
Some people like to remove the probes from their cooked meat by giving the cable a sharp tug, but that can weaken or break the seals at the transition that help to protect the sensor. A much better way of removing the probe from your meat is to grip the probe at the bed or at the transition and pull it out.
Whether you barbecue for your family or for competition, careful temperature control is essential to your success. Accurate, durable probes make that kind of control possible and ThermoWorks probes are the most accurate and durable probes around. That said, a little extra care can go a long way in extending the life of your probes. Take care to avoid chimneys, vents, hot spots, metal grates, and the hot steam from water pans. Avoid kinking your probe cables and use foil only sparingly.
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