The function or funtions of the water pan in the "WSM".

Discussion in 'WSM Owners (Weber Smokey Mountain)' started by james1970, Jan 22, 2015.

  1. Hello! I have been reading several Threads/ post in the forum about the use or lack of use of the water pan in the WSM, or any other smoker. I would like to first explain the main function of the water pan. The water pans main function is to help stabilize and hold the temp. for extended cooks between 180F to 270F. The steam from the water will in theory try to keep the temp. in the smoker around 212F, which is the boiling temp of water. This is in theory is the ideal temp. for the collagens to break down in the meats, and make it tender. (Meats such as brisket, pork shoulder(Boston Butt), rib's and  whole turkey). It also serves as a heat deflector for indirect cooking, and is completely un necessary for shorter hotter cooks above 275F, such as chicken or Tri Tip. Also the steam from the water does nothing for the moister in the meat! However it can effect the flavor and tenderness of the meat! (this part is arguable!) Yes here is where we get into the science and theory part of everything. The steam( H2O) from the liquid in the water pan in theory mixes with or reacts with the smoke( nitrites and nitrates) from the charcoal/ wood causing nitric acid( HNO2) to form. This in turn reacts with the salts, fats, collagens, and proteins in the meat causing nitrites and nitrates to absorb in to the meat. Which also helps preserve, tenderize, and flavors the meat with that lovely smoke flavor!!

    The use of the water pan is completely optional (Your choice), but it can be useful!!

    I personally have had success with the water pan and with out the water pan!! 

    Another thing I would like to add is please don't stress about the temperature on your smoker (WSM)!! ass long as it is with in 30 degrees (give or take) of your target temp. you are okay!! temperature fluctuations happen!! Because of climate, weather, quality of meat, or charcoal there are no constants in BBQ!! Just adjust your cooking times. Drink an adult beverage, and relax!
    Last edited: Jan 22, 2015
  2. jirodriguez

    jirodriguez Master of the Pit OTBS Member SMF Premier Member

    .... also part of the reason I like using water in my WSM pan is that as the coal pile burns down the amount of thermal mass in the pan goes down (evaporates). Which helps keeping the temps up towards the end of a long smoke. Since the whole point of the thermal mass is to absorb the heat energy and release it at a steady rate that means that as your fuel pile goes down more of the energy goes into keeping the thermal mass hot, so using a thermal mass such as sand/gravel means your thermal mass might actually start to work against you towards the end.

    No hard data on this just a general thought on the conservation and transfer of energy.
  3. Nice explanation, I use water most of the time. Now I have to get butts ready for tonight.
  4. jirodriguez

    jirodriguez Master of the Pit OTBS Member SMF Premier Member

    Yup.... I just use water, but the main thing is to have some sort of thermal mass, be it sand, gravel, water, etc. It really helps your smoker maintain a stable controlable temp.
  5. Thank you for your post, James1970, and apologies in advance for my questions, for I am not trying to be difficult.  I am new to the idea of smoking, but I have trouble following methods if based only 'on theory'.  My concerns are as follows - 1. 'the water pan's function is to stabilize and hold the temperature for longer cooks between 180F to 270F'.  My longest smoke thus far has only been about 5-1/2 hours, but I was easily able to hold a stable temperature using the dry method (in fact, left to do necessary errands and returned 3 hours later and the temperature had only changed 5 degrees).  So I am just having trouble understanding where one needs this stability, if one has the appropriate amount of coals and the vents have stabilized at the desired setting?  Do the coals not continue to burn at a relatively stable rate if the oxygen supply remains the same? I do not hold a degree in Physics or Thermodynamics, so please forgive if I am missing the obvious. Do the longer smokes significantly alter how the coals burn? 2. As this is not a chemistry forum and it has been some years since I studied such, I am unable to debate the degree of nitric acid formed with the steam generation, but even if some were, hypothetically, generated- to what degree would a 10 lb pork cut be able to 'see' such in its interior?  To think that this acidic component being laid down externally is able to affect the proteins 4-5 inches internal seems a stretch which is difficult to comprehend, but as the meat of a smoke does impart a taste of the smoke, perhaps this has validity, but one would need a control of a dry smoke held to the same temperature (perhaps this has been done, but as a reference isn't provided it is tough to review). Could the tenderness not simply be due to the low temperature for a prolonged time, in which the protein and collagen breakdown is occurring?  One other part of the study would be assisted if a third control arm were added in just an electric oven.  The smoke flavor wouldn't be present, but the judge of tenderness should be a fairly comparable analysis?  3. If the importance of using the water is to maintain the cooking temperature at 212, then why is plus/minus 30 degrees OK?
    Again, although I took some Physics and Chemistry courses many years ago, I am having trouble following this?  Has a study been done with the same amount of coal in two nearly identical WSMs (same age and number of cooks with similar coals and meats/poultry cooked), in which one is cooked dry and the other with the water method, with internal temperature probes assessing the temperature curves with plots to compare?  Please understand this is not an attempt to debunk, disprove, prove, or affirm any method, but for those of us just starting out, how are we supposed to filter out the 'theoretical' reasons for using a certain method when some of the discussions are opposite yet sound rather convincing by using scientific terminology which may or may not be analytically sound?
    As mentioned in my other thread, I have less than 10 smokes under my belt, so I have little basis for my discussion.  But what I have found, for smokes less than six hours, it has been very easy to hit a stable temperature if early on carefully regulating the vents, allowing five minutes or so between each subtle change, and observing the temperature effects has been done.  Because I have yet to have an issue with maintaining a stable temperature, I remain confused as to why this 'thermal mass' is needed?  As the discussion seems to imply it is for the longer smokes and these lower temperatures, it would be helpful to have some links to side-by-side controlled studies of the dry vs the wet or thermal method with temperature plots.  These most likely have been done, but I apologize that I haven't been able to find them.  There will be margins of error as the numbers will be small, but at least it will help some of us to understand.

    None of the above is meant to be confrontational or argumentative - just a newcomer to this wonderful field trying to understand what is being shared. Many thanks again for all of the interesting reads on this excellent forum.
  6. timberjet

    timberjet Master of the Pit

    Where temperature stabilization comes in to play is about 400 miles north of you where it is cold, wet, windy and frozen. We who live in the colder parts of the country need the thermal mass in there. Every time you take the lid off you lose a lot of heat. The hot thermal mass in there helps you recover your heat faster. Same with when the wind is blowing, or it is snowing hard. There are lots of other reasons. these are just a few. I do not use water in the pan. For one thing it takes a lot of energy to heat the water which is just using up more fuel and prolonging your cooking time.
    Last edited: Jan 23, 2015
  7. jirodriguez

    jirodriguez Master of the Pit OTBS Member SMF Premier Member

    Easiest way to think about it is this: Two pieces of metal one measures 12" x 12" x 12" the other measures 12" x 12" x 1". Heat both pieces to 700 °F, smaller piece has less thermal mass and will cool much faster, larger piece retains the heat much longer and radiates it out at a steady rate. Same concept in your smoker.

    Yes you can run without thermal mass in a smoker at a set temp, but it will require more energy to maintain that temp for the entire length of the smoke (read fuel consumption) especially when you open your smoker for any reason. With a thermal mass it uses a bit more energy at start up to get your thermal mass up to temp, but once it is up to temp it takes less energy to maintain the steady state over a long period of time - and when your open your smoker the larger thermal mass allows it to recover from the sudden drop in temperature much faster.

    This principle holds especially true in climates that are colder and or windy. Wind is actually your worst enemy when it comes to fuel consumption and steady temps. It can be a cold still day and your smoker will run fine, but add a 5-10 mph wind to that and your fuel consumption can almost double.

    I'm not aware of anybody doing a scientific study with numbers to back it all up with the WSM, but I have ran with and without thermal mass and always get much longer stable temps with opposed to without. For short cooks it isn't nearly as big of an issue, but if you are doing a 16+ hr. brisket you better have some sort of thermal mass or be prepared to reload with more charcoal mid smoke. Also as others mentioned thermal mass does not need to be water, there are several options people use on the forum.

    Another trick for cold windy smoking is to wrap your WSM with a welding blanket (or build a small enclosure). The welding blanket doubles as both a wind break and extra insulation - I can run my WSM in steady 10-15 MPH wind with an outdoor temp below freezing and still get a good 16+ hrs. of burn time at 250° on one 20 lb. load of charcoal. For comparison in the summer I can run 21+ hrs. on the same 20 lbs. of charcoal.

    Climate is a big factor so find out what works for you and run with it! [​IMG]
  8. dcarch

    dcarch Smoking Fanatic

    Thermal mass (heat sink) is a property of the mass (specific heat) of a substance which enables it to store heat, providing "inertia" against temperature fluctuations. It can take or give away heat, depends on ambient temperature.

    The issues with water in a smoker environment to be considered are the following:

    Water can never get above 212F (normal pressure), If you want your smoker to go above 212F, it will be a hindrance. Until all the water is evaporated away, which will be at the cost of 970.4 BTUs for each lb of water, after one BTU for each lb of water for each degree F to bring the water to boiling temperature. It cannot be a heat sink to stabilize the temperature by definition above 212F.

    If your are smoking runs below 212F, indeed water can help to stabilize the temperature, but, not that much, for each gallon of water, it can only give you a little more than 8 BTUs of heat for each degree F of temperature change.

    Sand, on the other hand can help stabilize temperature at any temperature of a smoker, but, you will be surprised how little it is, for each lb of sand to change one degree F, it gives out only 0.19 BTUs of heat. So if your steel tank RF smoker is 300 lbs of steel, heated to 270F, it will have in it about 6500 BTUs worth of heat stored, will a few lbs of sand make that much difference?

    Water in a smoker does one thing very good, it can help the keep the moisture higher.

    Last edited: Jan 23, 2015
  9. Thanks to all for contributing to the discussion. It seems clear if one lives in cold climates that some form of external insulation or internal heat sink would make sense.  As I live in the Southeast it is doubtful I shall ever encounter the difficulties which many of you face, but your efforts to counter Nature do make sense. It would seem the evaporation issue with a fluid would by its very nature make the issue of heat conservation and subsequent transfer later in the smoke more difficult to calculate and to rely upon, but if one could heat up a solid substance to a certain temperature, add it to coals already warmed to desired temp, and then let it continue in a rather steady state thermal equilibrium, then it should have a more dependable energy transfer curve. To ask the coals to heat a cold heat sink to desired temperature would seem to defeat the purpose, but if said solid material is added already warmed, energy from the coals will not have been lost bringing the heat sink up to speed.

    Interesting science behind a great past-time.  And again, thanks to all for assisting in the understanding of the 'why' behind the 'what we do'.
  10. Yes you're all right!! The water pan will and does hold heat even when the coals are burned out, hence it acts as a thermal heat sink.. Also in the colder climates such as the north west or north east you may find that to be extremely beneficial to your cook. You can save fuel ( charcoal), and time by putting hot water rather than cold water in in your water pan. I have also found that a cheap hot water heater blanket from the hardware or home improvement store, or a military surplus wool blanket will help my WSM hold heat longer and use less fuel when the temperature is cold out side.

    For those who live in the southern parts of the country the water pan is not as necessary In those climates you would only need to use it as a heat deflector to help distribute the heat and mix the smoke more evenly during your cook.

    Sorry in advance for it taking me a long time to respond. I am the father of teenage girls who play basket ball, and I am on the run a lot this time of year. I do still find time to BBQ in between games! No matter what!!!  . 
  11. timberjet

    timberjet Master of the Pit

    I have smoked for many years with vertical charcoal smokers and have tried everything. My conclusion after all that experimenting for all that time with all those smokers is no water. I use Pea gravel double wrapped in foil. Everybody has some scientificish opinion but in my experience this is what works best. Period.
  12. Indeed, timberjet.  And it is hoped through this discussion differing views do not take offense.  My viewpoint is simply trying to understand how our ancestral folks would have smoked a meal. Personally, I don't want to foil and spray and take the lid off and repeatedly check on the smoke.  My aim is not about creating that perfect taste to win a competition, but rather, as a working man (or woman) in the day 100 years ago, how would they have fixed a meal for their family and relatives?  Back then, and I do remember in the '60s, the cook was set, and because there were so many other duties required at the time, the smoke itself was not the center point, but rather the end result which was to feed everyone, and the meals tasted great.  Maybe because we were so tired and hungry from working we weren't that worried about the perfect taste, but that is the historical perspective I am trying to retrieve.  All of us have a different perspective, and that is what makes this form of cooking so great.  Thanks.
  13. No offences taken here falconNorthFL and timberjet. I agree with the gravel, sand, kitty litter, lava rock, ceramic briquettes, or what ever non toxic non flammable substance you would like to put in the water pan, because there again you are using it as a thermal heat sink to hold and distribute heat more evenly. That goes with the science that dcarch gave us, and my own statement (theory) that water can only heat to 212F then it tries to stabilize the temperature of everything around it to its own temperature of 212F. This works well if you are trying to cook a brisket at that temperature, and I agree with dcarch  it can be counter productive if you are trying to get to a higher temperature such as 275-300F for cooking chicken.  falconNorthFL if you go to the Weber web site and read about the history of the WSM you will find that  the main reason the WSM was designed and built in the first place was to try and emulate the style and flavor of the engineer who designed its European ancestors. He designed it with all of us back yard cooks in mind. He kept in mind that we like to modify and make everything our own, so he kept it simple in design! Anybody who has owned their WSM for any length of time has most likely modified it in some fashion to better suit there style. I have put a gasket kit in mine to seal it better, I have added an extra charcoal grill to the bottom to hold lump charcoal better, and I have added grommets so I can put my sensor probes for my Pit master IQ, or my Maverick digital thermometer.

    Just like most of us that smoke or BBQ our foods we are trying to get the taste that our fathers, uncles, grandfathers, and ancestors before them used to produce in their BBQ' d food when we were young.

    I do realize I created this thread / post to help people understand the purpose of the water pan in their WSM, but I would like to add this next bit of information to support every ones theories.

     After using my WSM for a while a friend and I decided to build an UDS out of a 55 gallon drum. My friend runs a stone counter top and floor shop, so we lined my UDS with left over remnants of Granite, and made a round Granite heat deflector for it, that goes toward the middle of the smoker where a water pan would normally go. I have found that by insulating my UDS like this it uses way less fuel than my WSM and holds heat for several hours longer. However all of this came at a cost! My UDS is extremely heavy (About 400 lbs.), so I only use it for really long cooks where I don't have to move my smoker..

    However I have also found through all of this that most upright barrel type smokers really don't need very much extra moisture added to the cook chamber. They create a moist cooking environment naturally because of their cylindrical design.

    Secondly I also  found that the WSM although simple in design is a very affective smoker for the beginner and even seasoned veterans. It is easy to set up and transport.

    I am sorry if I confused anyone or possibly even offended them!.    
    Last edited: Jan 25, 2015
  14. Many thanks for your reply, James.  I'll bet your hand-made granite-lined smoker really holds that temperature well and can smoke for a very long time!!  When I get some time I do want to research the history of smoking and BBQ in much more detail, for I must admit to knowing very little about its development throughout the centuries.

    Best wishes for some great meals and great times!
  15. timberjet

    timberjet Master of the Pit

    No offence here until you said kitty litter. Hahahaha.... I seriously hope no one uses kitty litter in their smoker. Used or not. lol Hey, could you post a pic or two of the inside of your UDS. I would like to see how you did it. I think that would be a good idea for me and mine here in the cold northwest. I am pretty good at scrounging stuff up.
    Last edited: Jan 25, 2015
  16. I quit using water long ago because 1) it burns more fuel than necessary (to heat the water), 2) maintaining the temp is easily done by closing vents and building a clean burning fire, 3) water also creates a mess to have to clean up not only in the pan but also in the sides/top of the cooker in the form of brown crap, and 4) I normally cook at higher temps than water allows me to go.

    Most folks on TVWB and TVWBB don't use water for all these reasons and more.
    Last edited: Jan 25, 2015
  17. dcarch

    dcarch Smoking Fanatic

    Good insulation is the single most important consideration in keeping good temperature control.

    In my 4.5 cu. ft. converted refrigerator smoker, I am using only a 300 watt light bulb to maintain temperature, and the 300W bulb only need to go on 1/2 the time.

  18. noboundaries

    noboundaries Smoking Guru OTBS Member SMF Premier Member

    I dry smoke the majority of the time. The empty water pan for me is just a heat deflector.  Consequently I don't use water, sand, gravel, clay, or anything in my water pan as a thermal mass to control temps. For temps under 300F I use my BBQ Guru that stokes and chokes the burning fuel with air to maintain temps.  Basically it is like setting the oven.  For temps over 300F I leave it off and just open the vents to let it run.

    It has been proven that more smoke will adhere to the meat in a moist environment.  I'll put some water in the water pan when I want to lay down more smoke flavor initially but I never fill the water pan.  I may use as little as a quart of water.  The most I'll use is 6 quarts on a longer smoke.  Both cases are called wet-to-dry smoking, something I learned about here on SMF.  The water is only there to enhance the smoke flavor, especially if I'm going to be wrapping meat.   
  19. Bottom line: Use what works for you and makes you happy.
  20. Interesting post. It jibes with my VERY LIMITED experience. I use water for ribs and butts (or at least the one butt I've smoked). No water for chicken as I'm trying for high temps and crisp skin.

    Good thoughtful posts by all.

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