| Temperature
Control Troubleshooting
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Originally
posted: 06/01/2000
Last updated:
01/08/2008 |
In this topic:
Ask an experienced owner what they appreciate most about the Weber
Smokey Mountain Cooker, and they'll probably say it's the ease of controlling and maintaining the temperature of the unit.
So, it's ironic that temperature control is one of the areas that frustrates
new WSM owners most. Sometimes the unit runs too hot...even with all
the bottom vents closed, the temperature won't come down into the
225-250°F range. Other times, even with a full charcoal chamber and all
bottom vents wide open, the temperature won't rise above 200°F!
Well, don't despair!
With these tips from experienced WSM users and a little practice, you'll
have your Weber Bullet's temperature on "cruise control" in no
time.
WSM Runs
Too Hot
The common
causes of the Weber Smokey Mountain Cooker running too hot, or appearing
to run too hot, are as follows:
Shiny
New Interior Surfaces
Weber
says the WSM may run up to 50°F hotter when brand new. The shiny interior surfaces reflect heat back into the cooker,
resulting in higher than normal cooking temperatures. However, after a
few cooking sessions, a layer of smoke and grease builds up on the
interior. As a result, it becomes less reflective and absorbs more
heat, which radiates out of the cooker and results in lower cooking
temperatures.
Don't be too concerned about this during your first few cooking
sessions. Some people report that they don't even notice this effect with
their new WSM. If you experience high temps during your first couple of
cooks, be patient and wait until you've got a nice coating of
smoke and grease on the interior surfaces before proceeding to other
remedies.
Weather And Sun Exposure Affect Temperature
Take wind and sun exposure into account when
determining how much charcoal to use, how and when to adjust
the bottom vents, and where to physically locate the cooker.
The WSM
runs hotter on warm, calm days than on cold, windy ones. It
also runs hotter when placed in the direct sun versus in the
shade. Did you know that on a spring day, a WSM sitting in the
sun with no charcoal burning can register 120°F or higher?
That's halfway to a target temperature of 225-250°F.
Wind can blow through the bottom vents into the charcoal bowl and feed the fire. This problem can be solved by moving
the cooker to a sheltered location, installing a wind break, or closing the
two upwind vents and managing the fire using the remaining downwind
vent. See Cooking In The Wind, Rain & Cold for
more information about cooking in windy conditions.
Cooker Temp Rises Naturally As Meat Cooks
During the early stages of cooking,
the meat is relatively cool and absorbs a lot of heat energy.
After it's cooked for a couple of hours, the meat doesn't absorb as much
energy and the cooker temperature begins to creep up as a
result.
So, some increase in temperature during a cooking session may
be normal. However, if the
temperature runs up well beyond the 225-250°F range, there may
be too
much fuel burning for the amount of food in the cooker.
Some Temperature Spikes Are Normal
The breakdown of charcoal briquettes can play a part in sudden temperature spikes. As ash
builds up and then falls away from the briquettes, new material for
combustion is exposed and the temperature rises, sometimes rapidly.
Also, smoke wood chunks may catch fire when the cooker is
opened, due to the introduction of air into the cooker. These are normal conditions
that cannot be
controlled, but such spikes will usually subside within 15-30
minutes.
Keep Water Pan Full
It's difficult to run the WSM over 275°F with a full water pan,
even with all the vents wide open. The water absorbs a lot of heat
energy and helps moderate the temperature of the cooker. Keep the
water pan full, checking and refilling every 90-120 minutes. Use cool
water instead of hot if the cooker is overheating.
Check Thermometer Accuracy And Placement
It's important to check the accuracy of your thermometer
occasionally. They can get knocked out of calibration after
being dropped, or sometimes a probe just goes bad and must be replaced.
See Testing Thermometers For
Accuracy for information on how to test thermometers and tips on
what to do if yours is inaccurate.
If using a probe thermometer to measure temperature on the
cooking grate itself, keep the probe away from the edge of the grate,
especially the bottom grate.
The edges are much hotter than other parts of the cooker,
due to heat rising around the water pan.
Check For Air Infiltration
Tight-fitting
parts make the WSM fairly airtight, which allows you to
easily control combustion and thus temperature using the air
vents. When you can't seem to get the
temperature down, even with all the bottom vents closed, air infiltration is
usually the culprit.
The two most common causes of air infiltration are a
poor fitting access door and an "out of round"
condition between the middle cooking section and the charcoal
bowl. A detailed description of these two problems and the
steps you can take to remedy them can be found on the Parts Troubleshooting page.
Don't worry about seeing a little bit of smoke puffing out
from around the access door or the edge of the lid.
This is normal, especially when the unit is new, and will go
away once you get a good layer of smoke and grease built up on
the inside of the unit.
Difference
Between Temperature At Lid Versus Cooking Surface
As discussed in greater detail on the
Measuring Temperature In The WSM page, the temperature measured at
the lid is 12-15°F higher than the actual temperature at the
top cooking grate. If you're targeting 225°F at the top grate,
look for 237-240°F on the lid thermometer.
Change Amount Or Type Of Fuel
Most folks can use the methods outlined on the Firing
Up Your Weber Bullet page to achieve good temperature control. If you've
considered all the items listed above and are
still having problems, perhaps you're using too much fuel for the
amount and type of meat being cooked. Firing up 10 pounds of charcoal to cook
a single chicken or slab of ribs is
overkill and will make temperature control difficult--you've got too
much heat, not enough meat.
Try to determine just the right amount of fuel that allows you to
cook a given quantity of meat for the desired time and temperature,
with some heat left over for good measure. This comes with experience,
so make sure to use a cooking log to track
fuel usage from one cooking session to the next.
For example, 1-1/2 to 2
chimneys of hot Kingsford charcoal briquettes is enough to cook four
whole chickens or eight slabs of baby back ribs for up to 5 hours at
225-250°F.
Also, remember that some charcoal varieties and brands burn much hotter
than others. Lump charcoal burns hotter and faster than briquettes. Try a new product and see if that makes a
difference.
Stop Peeking
Every time you open the cooker to gaze upon your barbecue
masterpiece, you let in an uncontrolled volume of air that whips
the coals into a frenzy. Open the cooker only when it's necessary
to service the meat, fuel, smoke wood, and water. Combinations
Of Factors
Keep in mind that a temperature problem may be caused by a
combination of the factors listed above. For example, a run-up in temperature late
in a cooking session might be the result of 1) the cooker is
now in full sun, no longer shaded by your house; and 2) the natural
increase in cooker temperature that occurs as the meat takes on
less heat energy. Look for combinations of factors that may be
explain what's happening to the cooker.
If
All Else Fails...
If the bottom vents are fully closed and the temperature still won't
come under control, close the top vent 50%. If even this fails, use tongs and heat-resistant gloves to remove some fuel from the
cooker through the access door. If you're feeling lucky, lift the
middle cooking section off the charcoal bowl with the lid, meat, and
water pan intact to access the fuel. This can be dangerous and
messy, especially if you dump the contents of your cooker on the
ground or into the hot coals. Remove the cooking section at
your own risk. Weber warns that you should never move a hot
cooker and you should never operate it unless all parts are in place.
Under no circumstances should the coals be doused with water in an
attempt to bring the temperature under control. This will coat the
meat with ashes and may crack the charcoal bowl's porcelain finish.
WSM
Runs Too Cool
Here are a
few things to consider if the cooker runs well below the 225-250°F range:
Check
Thermometer Accuracy
As mentioned above, it's possible that the thermometer may be
the culprit, registering a low temperature reading.
See Testing Thermometers For
Accuracy for information on testing methods and tips on
what to do if your thermometer in inaccurate.
Weather
And Wind Exposure Affect Temperature
Take weather and wind conditions into account when
determining how much charcoal to use, how and when to adjust
the bottom vents, and where to physically locate the cooker.
The WSM will require more fuel on a cool, damp day than on a warm, sunny
one. Wind, more so than cold air temps, will rob the cooker of heat.
Start out with more fuel, and move
the cooker to a sheltered location or install a wind break. See
Cooking In The Wind, Rain & Cold for
more information about cooking in windy conditions.
Change Amount Or Type Of Fuel
The WSM will run too cool if too little fuel
is used for the amount of meat being cooked. Especially during the early
stages of cooking, the meat will absorb a lot of heat energy, causing
the cooker temp to drop significantly. Firing up 1 chimney of charcoal to cook
a 13-pound brisket plus two 8-pound pork butts just won't cut
it--you've got too
much meat, not enough heat. Next time, try using more fuel.
Some people find that even with the charcoal chamber filled to
overflowing, the cooker won't hold 225-250°F for more than a couple of hours. If this is your problem, try
switching to a different type or brand of fuel. Some brands of charcoal briquettes burn much hotter
than others. Kingsford seems to be the brand that burns hottest,
longest, and most consistently. If you're using something other than
Kingsford, buy a 20-pound bag and see if this solves the problem.
Lump charcoal can sometimes present difficulties because it does not
always burn long or consistently. It generally burns much hotter and
faster than briquettes, but may drop off in temperature after a few
hours, requiring the addition of more fuel. Try switching to another
brand of lump to see if it provides a better result. Otherwise, try
charcoal briquettes instead, which are manufactured to provide long,
consistent heat.
Check Location Of Water Pan
I received an e-mail from a man who seemed to be doing
everything right, but still couldn't get his WSM above
200°F. After exchanging a series of messages, I
determined that he was placing the water pan right on top of the charcoal chamber, effectively
smothering the coals!
Make sure the water pan is placed in the middle cooking section
on the lowest set of flanges, right beneath the bottom cooking grate.
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