Reverse Flow & OffSet Smokers: How are they Different?
From the Smoke Stack to the Food Quantity to the Height of the FireBox...
There are several differences between a Reverse Flow Smoker and an Offset Smoker!
Today we are gonna go over those differences and hopefully help you decide what Smoker would best for your BBQ needs!
Check out this video to for the answers:
"What's the difference?"
I get this question a lot from guys lookin at plans at smokerplans.net. They get to lookin at difference plans labeled reverse flow and offset and wonder what they'll be getting for each. And the truth is any of our plans will work for either style of pits. You just have to make changes on your end during the build!
So let's first talk about the difference in:
As we go through these different aspects of construction, the one thing you need to keep in mind is AIR FLOW. You always construct for the most effective air flow. If you follow that rule of thumb, then a lot of what we will cover will make sense.
1. BAFFLE PLATE/THROAT BAFFLE
In a reverse flow smoker there is a baffle plate in the cook chamber. It's welded in solid, goes all the way across the firebox( or the main cooking chamber) until it gets to the other end of the smoker.
And there's usually a gap right there at the end where all the smoke and the heat and the air mass is forced to take 180 degree turn upward and go all the way back towards the firebox.
That's why we call it a Reverse Flow Smoker.
[First of all there are TWO main kinds of Offset. You have a Traditional Offset and the Texas Style Offset.)
This Kind of Offset Smoker has tuning plates rather than a baffle plate and the smoke stack is on the opposite end of the cook chamber from the firebox.
Texas Style Offset:
In this type of offset you'll find the cooking chamber is OPEN, meaning it has NO BAFFLE PLATE.
For the sake of this discussion we will talk about the Texas Style Offsets when comparing to Reverse Flow.]
In an offset smoker there is NO HORIZONTAL BAFFLE PLATE, meaning the cook chamber is open. In the offset smoker, We are going to try and direct the flow of smoke, heat, and air mass upward at (almost) a 90 degree angle as fast as we can from the throat.
In the cook chamber just past the throat opening is a Vertical Baffle or sometimes a scoop like plate. This plate turns the heated air mass straight up to cause a downward convection of the heated air mass.
What we're doing with that is we're trying to get the flow of our air mass to go all the way up and go across the top of the cooker and it's going to convect itself downwards towards the smokestack.
So on pretty much all the different offset style smokers you're going to see the smokestack is at the opposite end of the cook chamber and it's mounted low on the cook chamber at grate level.
2. SMOKE STACK LOCATION
The difference in smoke stack location is also important when considered offset vs. reverse flow. If you haven't already guessed the Smoke Stack is where the smoke goes to escape the cooker.
On a reverse flow smoker our smokestack is mounted on the Top Dead Center of the Cook Chamber.
In a Reverse Flow Smoker we are cooking from the BOTTOM UP. Because of that, once we get up through that baffle plate, we don't want to create a whole bunch of restriction in our air mass. If we restrict that air mass, we will end up losing temperature and causing condensation.
So, the best place for the Smoke Stack is at the the TOP where the air mass will exit the cook chamber before it loses it's heat. This process gives us maximum convection in this type of cooker.
The smokestack on an offset is going to be about Cooking Grate Level and it's going to be on the the opposite end from the firebox.
Since we are cooking from the TOP DOWN in an offset smoker, you'll want the bottom of your smoke stack at Cooking Grate level to insure that the air mass gets maximum convection before exiting the smoker.
3. HEIGHT OF THE FIREBOX
The Fire box is where you will put your wood for burning. And the height of the firebox will greatly assist in the effectiveness of your cook. And it's also another notable difference between open offset and reverse flow smokers.
In a reverse flow smoker, you want to keep the fire box LOW in the cook chamber, because you are going to mount the baffle plate on top of it.
If the fire box is low then your air flow will not have to ascend UP into the cook chamber, but rather flow into it naturally. You don't want your air to have to make a DOWN TURN as it enters the cook chamber, therefore keep your firebox LOW and wide open. With the wide open flow coming in from your firebox, this absorbs heat into the baffle plate which radiates upward. Bottom of Food gets cooked. Then the air flow turns at the baffle plate gap and cooks the top of the food.
With this we end up with a dead even cook chamber temperature.
In an offset smoker, we're going to mount that firebox, most of the time, about 50% up the sidewall of the cook chamber.
As we stated before we want to cook from TOP DOWN in an Offset smoker. So, in addition to the firebox being set 50% up the wall of the cook chamber, you want that throat opening wide open. This will insure that the one end of your cook doesn't get roasted, and you also don't have air flow restriction.
Since there are distinct differences in construction on these two smokers, there are also different ways of operating. We will talk about those differences such as Temperature control, start up sequence options and Temperature zones.
1. Temperature Control
Controlling temperature is an important aspect of cooking in your smoker, but of course it's controlled differently under different construction parameters.
In a reverse flow smoker, the fire will only require periodic stoking. There is a reason this type of smoker is called a Set it and Forget smoker. You can almost, like clock work, throw another piece of wood on the fire about every 45 minutes. And if you need to adjust your air flow you have air inlet dampers that enable you to open or restrict that air flow and therefore the temperature. But you're still going to need to build the fire up, prior to that point of "set it and forget it".
In an offset smoker, temperature control can be a bit trickier and require more attention. Often times you will need to resize your fire, and adjust your smoke stack damper blades to achieve a consistent temperature. And there is also less need to adjust the air inlet damper than there is on a reverse flow smoker.
2. Start-Up Sequence
One thing to remember for starting up your fire in a smoker: Charcoal bed is where the heat is coming from, while the wood is where the flavor comes from. So keep that balance in mind as we go through these two start up sequences.
For a reverse flow, the best way to start your fire is to establish a good coal bed and then add wood on top of that. This will insure you get a good fire brewing.
Since the offest has no baffle plate to absorb the heat from the firebox, the start sequence may take more time. Sometimes guys will use a weed burner torch to ignite the initial coal bed and first batch of wood. And sometimes using that same weed burner to pre-heat the cook chamber itself. Either way the fire will take slightly longer to reach optimal temperature for cooking and may require more prep work.
3. Temperature Zones
With different constructions comes different areas of temperature zones. These are zones where the temperature is optimal for your cook.
As far as temperature zones go, reverse flow smokers have an even temp throughout. Because of the incoming heat from the firebox and the heat radiating from the baffle plate, your reverse flow doesn't really have distinct cold or hot spots. It's all even.
Now, that doesn't automatically qualify Reverse Flow Smokers as better than offsets, because you sacrifice a certain amount of cook quality when your heat and smoke is not as adjustable as it is with an offset.
In an open air offset with a throat baffle, you will have cooler temperatures near the firebox and hotter temperatures as your go away from the firebox. And the HOTTEST part of this type of smoker will be at the exhaust at the cooking grate level.
COOKING STYLE :
Since the construction and operation of these two smokers are different, so are the cooking styles. We will talk about how each will have a difference in cooking direction, flipping & rotation, and quantity of food.
1. Top/Down vs. Bottom/Up
As briefly mentioned before, in a reverse flow smoker, your meat is cooked from the BOTTOM UP. This is caused by the low fire box emanating heat through it's open throat into the area BELOW the cooking grate & baffle plate. As that hot air travels horizontally, the baffle plate prevents it from traveling directly upwards, which in turns forces the air flow to turn at the end of the baffle plate opening and cook the top part of the meat. Also, in this way, the heat absorbed in the baffle plate radiates from about the center of the cook chamber upwards giving a different cook than an offset.
In an offset smoker, you are cooking from the TOP DOWN. As we know, heat rises. Now, in a reverse flow smoker, we have a baffle plate that prevents heat from rising all the way to the top of the cook chamber. But in an open air offset there is no baffle plate. So, the hot air comes into the smoker, and fills the cook chamber starting at the top, until it reaches the grate. Once the hot air fills to that level, it will reach the exhaust and then a draft will be created, equalizing itself in the cook chamber.
2. Flip and Rotate
Since in a reverse flow smoker, the temperature spreads evenly there is no real need to flip and rotate your food. The temperature that surrounds the meat is being evenly distributed on all sides and therefore cooks it thoroughly.
Since the cooking direction in an offset comes from the top down, in an offset smoker you will need to flip and rotate your food as needed. And you will also need to take into account the placement of your food in regards to temp zones and food racks.
3. Quantity & Variety
Since the air flow and the temperature in a reverse flow smoker is so consistent, and easily maintained, it is the better option for higher food amounts of the same consistency. For example if you were cooking for a fundraiser, and you need a large amount of food, that didn't require much attention, and was not made for competition, a reverse flow smoker would work best.
The benefit of having certain temperature zones within an Offset smoker, makes it more suitable for cooking different kinds of meat of various sizes. If you were cooking for fun, and trying different kinds of meat then the offset would be the better option. For example, if you were cooking brisket and chicken at the same time as sausage, an offset would be better because you could use those different temp zones to your advantage.
Reverse Flow and Offset Smokers have notable differences in Construction, Operation, and Cooking style.
Construction: In a Reverse Flow Smoker, there is a baffle plate in the cook chamber, a Smoke stack that is located in the top dead center of the cook chamber, and a LOW firebox. In an Open Air (or Texas Style) Offset there is NO baffle plate (but instead a throat baffle or a scoop style baffle in the throat of the cook chamber), the smoke stack is at cooking grate level and is on the opposite end of the firebox, and the firebox is about 50% up the cook chamber wall.
Operation: In a Reverse Flow Smoker, temperature control is periodic and regular (set it and forget it), the start up sequence is simple, and doesn't have temperature zones, but has a consistent temp throughout. In an offset smoker, temperature control is more involved & may require changing fire size, the start up sequence can be simple (but may require some prep such using a torch), and it has distinct temperature zones(Exhaust: Hottest ,By the FireBox: Coolest, Opposite end of Firebox: hot).
Cooking Style: With a Reverse Flow Smoker the heat/airflow cooks the food from the bottom up, which doesn't require any flipping and rotating, and is ideal for cooking great quantities of food of similar consistencies (ideal for fundraisers, resturaunts, etc.) With an Offset smoker, the heat/airflow cooks from the top down, which means the food needs to be flipped and rotated and closely monitored, and the cooker is ideal for fun cooks and cooks where your are doing a variety of meats (sizes, consistencies etc).
You can also learn how to Build YOUR OWN offset or reverse flow Smoker with our Build With Us Online Course!
And if your are more of a Cooker than a Builder and you'd like to get one of these Smokers Built for you you can always give us a call for a quote at 573-612-1315!