hey guys welcome to mad scientist barbecue I'm Jeremy odor and today I'm going back to my chemistry teaching days a little bit and we're gonna examine the science about water pans do they work should you use them what are the considerations when you make that decision now I'm gonna be talking a lot about numbers in this video but do not let that intimidate you there's a lot of calculation that went into where I got these numbers a lot of dimensional analysis and stuff that I pulled out of my chemistry tool book to try and figure these things out I'm gonna spare you all the details but I'll give you the big important numbers that are going to factor into how you make your decision about whether or not you want to use a water pan also I'm going to be drawing in some examples that might blow your mind about the energies involved when using a smoker now when I was thinking through this there were two questions I wanted to answer question number one is does the water pan contribute a significant amount of moisture to the cook chamber number two does it suck up too much energy and make your smoker inefficient and to answer the first question we have to start with the wood that we're using so let's go over some basic facts about the wood I use almost always white oak sometimes pecan but we're gonna use white oak as our example and you can draw conclusions about other wood types from that as a basic model now first I chord of wood is four feet by four feet by eight feet so what does that make it a hundred twenty eight cubic feet I think it does 16 a 20 yes okay now in that court of wood typically once the wood has become seasoned it weighs about 4,200 pounds and pardon my bad handwriting I've never had great handwriting so here we go 4,200 pounds 4,200 pounds in a quart of white oak now that sounds like a whole bunch and it is okay and of that 4,200 pounds by the time it's seasoned there's about 20% moisture 20% moisture in the wood so that means that there are 840 pounds of water in that quart of wood that's a lot right it's only 20% but it's a significant amount of water so when you're burning that wood gonna be releasing that water that's trapped in the wood into the cook chamber so the question have to ask is is that way more water than what I'd be contributing with a water pan is it even worth my time to include a water pan so that's what we'll investigate here now wrote these numbers out so this would be faster and easier now a couple things you have to know before I explain what these numbers mean typically for me a brisket cook which is going to be our test example here takes about 16 hours of that 16 hours about 12 hours is unwrapped give or take also when I put a water pan in there that water pan is a hotel pan so I use those to hold water because of a relatively large surface area and right about the time it's time to wrap those water pans are either almost empty or completely empty so that is what I'm working with when I'm doing these calculations now the first question there are sixty nine point six pounds of trap water in the wood that I use during the first 12 hours when the brisket is unwrapped I'm discounting what happens after the wrapping because it's protected from the outside water anyway so during that 12 hours about 70 pounds of trap water is going to be released from that wood and then go through the cook chamber also one water pan that I use holds about 11 liters of water or 24.2 pounds of water so if you're just looking at this you would say that adding one water pan adds about 35% more moisture than what you would get with just the wood two water pans 70% three water pans a hundred five percent and if you did for water pans went nuts with it you get a hundred forty percent more water that's a lot more water that's two and a half times as much as you started with that's what you might think but here's the issue that would be completely wrong and the reason behind it is chemistry to understand why those first numbers that we generated for how much extra moisture we get are wrong we have to think about what wood is made out of now we know that it's 20% moisture but the part of what that isn't moisture is made up of three main components one is cellulose one is hemi cellulose and the third is lignin okay and they're all primarily carbon hydrogen and oxygen and when you burn those things you produce mainly two compounds carbon dioxide and water vapor so you could have wood that's completely dry with zero water trapped in it and when you burn it you make water so even propane when you burn propane it produces carbon dioxide and water vapor if you've ever fired up a grill and it's really cold or you light a fire somewhere next to some metal a lot of times you'll get condensation of water on the metal surface because you have the water vapor from the fire that meets the cold metal and condenses and makes a liquid water I remember one time I saw somebody explaining how to run a smoker and he said that oh that that water on the metal that's the water that's coming out of the metal it was trapped in the middle it was not trapped in the middle that is simply condensation of water vapor now as an example of this right here we have the basic formula of cellulose so cellulose is about 40% of white oak and what you have is basically glucose molecules stuck together that's not super important but what is important is you take that stuff you burn it with oxygen and you make co2 and h2o so in addition to the water that's trapped in the would you make water simply by burning the solid components of the wood now to make this a little simpler even I wrote the names underneath we have cellulose plus oxygen makes carbon dioxide and water vapor and the same basic process is true for hemi cellulose and lignin and they make up about 90 92 percent of white oak and then there's some other smaller extractives they're called that make up a small portion but they will also burn and produce majority of the same compounds now disclaimer here wood does not undergo complete combustion if it did then smoking with wood would give you no more flavor than if you smoked with propane and that wouldn't really be smoking at all would it but the majority of what you're producing is this stuff and it's only the tiny tiny minority of other products that flavor the meat so white oak has vanillin in it so associated with vanilla flavor so those kinds of things will flavor the meat but they only make such a tiny fraction of what the wood actually produces when it burns that for our purposes today the difference is so small that it really makes no difference to our purposes when we're talking about water pants I want to clarify one thing just a little bit more complete combustion is when you take something and you burn it and you make only carbon dioxide and water vapor that's it that's to say that you don't make anything else whenever you burn wood you never achieve complete combustion when you burn propane you get pretty darn close that's why propane doesn't really taste like anything so a complete combustion is only carbon dioxide and water vapor and there's other compounds that you form from like side reactions and other stuff going on in the burning process or what gives wood smoke a specific flavor so for our purposes today we're gonna assume that it gets so close to complete combustion that we're gonna base all our calculations on complete combustion now when we take into account the water that comes from the combustion of the wood we have 78 pounds of water that comes from cellulose 52 pounds of water that comes from Hemi cellulose and 46 pounds of water that comes from the combustion of lignin in addition to about the 70 pounds of water that we had trapped in the wood itself that means that during the 12 hours when I have briskets on my smoker unwrapped the wood contributes a hundred seventy-six pounds of total water now that's a lot of water after doing all this and we look at the amount of water contributed by those water pans now we have a more accurate estimation of how much extra water they provide in the cook chamber by adding one of those plants I add nine point eight percent of water that's some is it enough to matter maybe maybe not two pans 19.6% three pans 29.5% four pans 39.3% by the time you get to four pans that's a pretty big difference an extra forty percent almost of water that's going through the smoker it seems to me to be a big deal but when I look at the volume of those water pans in relation to the size of my smoker I see it's not really taking up all that much volume one pan is only 0.5 8% of the volume of the smoker of 500 gallons for water pans is only 2.32 percent of the volume of the cook chamber itself now to translate to say a 60 gallon backyard smoker all you'd need to do to get the equivalent of four pans of water in my smoker is a half-size Hotel pan that's something that would hold about 5 liters of water so not too crazy so to answer question number one it sure seems that water pans do add a significant amount of moisture to the cook chamber now to answer the second question does using a water pan or multiple water pans ruin the efficiency of my cook now when I use my 500 gallon pit and I use it for say 16 hours to do a full brisket cook you know cook 2025 briskets in there I produce about 2.8 8 times 10 to the 9th joules okay what that means is it's a lot of energy to put it in perspective it's about the same amount of energy as 1,500 pounds of TNT so the reason your smoker doesn't blow up while you're burning wood inside isn't the total amount of energy it's the rate at which the energy is released TNT obviously releases its energy extremely fast but the wood has a lot of energy stored in it and you're using a lot of that energy to cook your food now the question does the water absorb too much energy well the water absorbs 1.1 and 4 times 10 to the 8th joules if it all heats up to 212 degrees Fahrenheit and then evaporates so I think that's a good approximation and that's about 4% of the energy that you produce but keep in mind that you're not using that energy 100% efficiently anyway the smoke and air that leave your smoker are still hot so you didn't absorb all of that energy so an estimation would be that maybe this is closer to 10% of the total energy that actually gets absorbed by the cooker and the meat that's in the cooker so is it a ton of difference no is it a significant difference yeah you'll burn less wood if you don't fill up your smoker with water pans is it worth it I don't think so for two reasons number one you want that extra moisture in the cook chamber and the second reason I'll show you right now don't be intimidated by the graph if you don't like graphs don't worry I'll explain exactly what it means in the end but just give you a breakdown of what it is here we have energy on this axis and we have the number of molecules okay if that doesn't mean anything to you don't worry what I'm talking about is how much energy the gas molecules have that are produced from a fire in this case we have two different temperatures so I use blue for the low temperature red for the high temperature and this dotted line represents molecules that have enough energy enough heat energy to burn your meat okay this would be the peak right here that's the temperature of the gas produced in a lower temperature fire this peak right here would be the temperature of gas produced in a high temperature fire now these Peaks aren't that far separated from one another but the important thing is how many of those molecules have enough energy to burn the meat so if you look at this even though these Peaks aren't too separated from each other when you cook at a higher temperature way more molecules have enough energy to burn the meat whereas at a lower temperature number of molecules would have enough energy to burn your meat so all that is to say this okay if you're trying to cook hot make sure that you have something there to absorb the energy of the really really fast moving high temperature molecules in there high-energy molecules so for that reason I would say that it is a great idea to use a water pan not only because it adds a significant amount of moisture to your cook chamber but number two it absorbs the energy of those really excited molecules and helps to prevent the meat in your smoker from burning now using water pan does use up more energy and makes your fire a little bit less efficient but I would much rather burn a slightly less efficient fire without burning the meat than to burn a more efficient fire and risk burning of the meat so for that reason I highly recommend that you use a water pan or water pans depending on the size of your cooker so that you get ideal BBQ weather in the cook chamber of your smoker what other note is when you include the water pan make sure that it has enough surface area that is it's not too deep so that it can provide lots of moisture to the cook chamber if you have something that you know might have a lot of volume but the actual exposed part is really small like I imagine a five-gallon bucket a lot of water there not a lot of place for it to escape that would not be ideal I would say something that's nice and shallow nice and flat and then you'll get the best quality results from using that kind of setup as mad scientist BBQ I feel it's my obligation to try to explore some of the science behind why we do what we do in barbecue to find out what's a myth and what's true and it appears to me at least that including water pan is something you definitely want to do if you enjoyed this video you can look for other scientific videos that I'll be putting out in the future but make sure to LIKE comment and subscribe to this channel and hit the notification valve so that when I put out those videos you get notified and you can follow along also you can follow me on Instagram trying to increase my presence there and twitter at mad scientist BBQ well see you guys next time with all the craziness and stuff going on right now a lot of people have their kids at home and they probably still have classwork and I don't know how much instruction they're getting I spent several years working as an AP chemistry teacher and ap biology teacher and a number of other different subjects so if any of your kids need help you want to hire a tutor for them you can contact me at my email and we'll see if we can work something out to maybe do some tutoring remotely
