Pellet Grill Smokestack Cap Adjustment or Height (How Much Open or Closed?)

A pellet grill is a great way to cook tasty, smoky food without the hassle of using charcoal or wood. However, if there is a thick white smoke due to incomplete combustion, or there are temperature fluctuations in a pellet grill, it can cause the food to taste unpleasant. Pellet grill smokestack is one of the ways to prevent these problems.

So, what’s the purpose of Traeger or Pit Boss pellet grill smokestack cap adjustment? Smokestack or chimney cap adjustment on a pellet grill allows to direct and remove the excess smoke out of the pellet grill. Lowering the cap of the pellet grill smokestack can hinder the airflow and affect the performance of a pellet grill due to inefficient combustion. Moreover, the cap of the chimney on a pellet grill also keeps the rain from entering the grill as it can damage wood pellets and affect combustion. Lastly, too much raising or lowering the smokestack cap on a pellet grill can impart a negative impact on the pellet grill. So, there is a trade-off while adjusting the pellet grill chimney cap height for efficient cooking.

Science of Working of Smokestack

Being a mechanical engineer, I have researched a lot on the thermodynamics of the smokestack. You will see smokestack/chimney in different places such as on your house roof, factory places, and on grills. The working of the smokestack or a chimney is based on the convection principle.

First, let me tell you in simple words what convection really is.

In a convection process, the hot air rises from a region, and the ambient cold air takes the place of the hot air. This is the same principle we observe when a chimney or smokestack is installed on a grill. There are hot flue gases inside the grill that are produced as a result of the combustion of fuel.  These flue gases expand and pass with high pressure through the chimney. As a result, the fresh ambient air takes the place of the flue gases to maintain a steady environment inside the grill.

The height of a chimney creates a large draft due to a greater differential in pressure. The pressure decreases with the elevation. So, the greater the height of the smokestack, the larger draft will be created. This is quite important if you’ve a large fire pit to burn coal or wood as the flue gases need to be evacuated through smokestack so that the fresh air can be brought in for efficient combustion and maintaining the temperature.

Why Do Pellet Grills Have Smokestack?

The purpose of a smokestack on a pellet grill is to keep the water and debris out of the pellet grill. In the case of a pellet grill, there is less control of smokestack or chimney on the temperature and smoke management. Moreover, the stack opening on a pellet grill acts as a vent to remove the excess smoke out of the pellet grill. So, instead of having stagnant smoke inside the pellet grill, which could impart undesirable black marks on the meat due to too much buildup of creosote, you would want to keep the smoke flowing around the meat.

If the smoke does not exist out of a pellet grill, it will become stale and dense. As a result, the smoke stain can not only damage grill parts but can also impart a bitter taste to the food.

Smokestack opening plays a greater role in the case of offset smokers. This is because in offset smokers there is no induction fan to keep circulating the fresh air inside the firebox for the combustion of coal or wood chips.

In pellet grills, there is an induction fan that keeps on circulating the air for efficient combustion of wood pellets. In older versions of the Traeger pellet grill and Gen 1 of Pro Series of Pit Boss pellet grill, a conventional controller is installed in which the temperature of a pellet grill is maintained by controlling the auger motor.

The auger motor is paused and turned on at specific intervals to maintain a temperature in the pellet grill, while the induction fan speed remains the same across all temperatures. However, there are modern versions of Traeger, such as Pro 575 and Pit Boss 1100 Pro Gen, which are equipped with PID controllers.

These PID controllers are different from conventional controllers in the sense that they keep on changing the auger feed and induction fan speed to maintain the set temperature inside the pellet grill. Similarly, all models of Recteq pellet grills have PID controllers that also vary the fan speed and adjust feed rate for controlling the temperature.

In addition, the heating system in pellet grills is centralized compared to the offset smokers. The firepot from which the heat is being radiated is placed at the center. A heat baffle plate is placed on the firepot to evenly spread the heat throughout the pellet grill, unlike an offset where the heat source is, well set off to the side. So, a smokestack on a pellet grill cannot have a significant effect on how the piece of meat cooks due to a change in airflow.

So, the point of all this discussion is that there is very little effect of a smokestack cap adjustment on the food flavor and the temperature regulation of a pellet grill, provided that the induction fan of a pellet grill is working fine and the controller is not malfunctioning. You can check out my guide on Pellet grill troubleshooting for more details.

So, if you ask that the cap of smokestack on a pellet grill should be kept open or closed, I would suggest keeping the chimney on a pellet grill opened and screwing it up to a distance specified by the instruction’s manual of a pellet grill. Smoke always takes the least resistant path to flow.

If you fully close the chimney cap on a pellet grill, the smoke can exit through the seam between the grill lid, hopper, and grease drain. Moreover adjusting the smokestack cap on a pellet grill to a specific distance also optimizes the airflow across the pellet grill.

That’s why pellet grill companies recommend raising the chimney cap on the pellet grill to a certain distance.  

Here are the recommended smokestack cap adjustments on the pellet grill by different companies.

  • Traeger recommends adjusting the smokestack cap up between 1 to 2 inches.
  • Z-grill is pretty specific as it recommends setting the chimney cap of the pellet grill to 8mm.
  • Green Mountain Grill says to use two fingers as an initial height of a chimney cap on a pellet grill, and then, adjust higher if you have temp or combustion issues. The maximum chimney cap opening for GMGs should be 2 inches.
  • Campchef says the gap of a chimney cap on a pellet grill should be approximately 1’’- 1 ½’’ in summer. In the winter and windy weather, the gap should be approximately ½”.

As far as the length of the smokestack is concerned, it doesn’t make any difference for pellet grills. The length of the smokestack matters only in stick burners using only a natural draft.

Smokestack vs Vent Holes on a Pellet Grill

On pellet grills, the purpose of smokestack and vents is the same i.e. to provide the least resistant path to excess smoke to exit the pellet grill so that the food and grill parts are not affected by the black stains of the smoke. You will notice that the pellet grills, on which there are vents, will not have smokestack installed on them. This is because the vents are serving the purpose of keeping the smoke flowing.

As far as the cost is concerned, the pellet grills with the vent holes are cheaper, while there is an additional production cost to attach a smokestack to a pellet grill. Moreover, according to persons on different forums, the smokestack on a pellet grill also improves the aesthetics. Another advantage that vent holes on the back of pellet grills offer is that you can insert multiple meat probes easily through them.

The disadvantage of vent holes in a pellet grill is that they can’t prevent rain from entering the pellet grill. So, you have to place pellet grills with vent holes under a shelter or canopy. Another disadvantage of pellet grills with vent holes and no smokestack is that the gusty wind can cause extreme temperature fluctuations when it blows through the vent holes on a pellet grill.

On the other hand, some pellet grills like Pit Boss 700FB have an opening with a gasket on the right side where you can add a smokestack. In that case, you have to make sure to seal odd the vent holes of the grill using a high heat foil tape as the smokestack will be enough to provide the least resistant path for the smoke to exit.

You can check out the video below in which the guy is installing a smokestack on his Pit Boss 700FB pellet grill.

You can find the best smokestacks for pellet grills here.

Does Closing Smokestack Cap Affect Smoke Flavor in a Pellet Grill?

Closing or decreasing the gap of a smokestack cap on the pellet grill will not have any effect on the amount of smoke being generated by the pellet grill at the specified temperature. A small adjustment of a smokestack gap on a pellet grill is performed to control the airflow across the pellet grill in extreme weather conditions. So, if you want to enhance the smoke flavor in a pellet grill, you can use a smoke tube.

Can Smokestack Adjustment On a Pellet Grill Affect Temperature?

If the smokestack gap on a pellet grill is adjusted based on the recommendation by the respective company, it will not have a significant effect on the temperature inside the pellet grill. However, the condition is that the smokestack on a pellet grill should be clean. It should not be dirty with soot/black carbon.

The black carbon accumulation in the smokestack can cause temperature fluctuations inside the pellet grill. It is recommended to clean all parts of a pellet grill after every third short cook or after every long cook.

If you find temperature fluctuations in your pellet grill and the smokestack cap distance is according to the owner’s manual, don’t try to mess up with it. I would advise you to check wood pellets quality and other parts of your pellet grill like ignition rod, auger motor, firepot, temperature probes, and controller. You can also check my guide on fixing temperature fluctuations in a pellet grill for more information.

How To Clean a Chimney On a Pellet Grill?

When subjected to a prolonged cooking period, a smokestack or chimney on a pellet grill is subjected to carbon, ash, and grease buildup. To clean the chimney on a pellet grill, I’d advise you to first take a wire brush to strip the buildup off the walls of the chimney on a pellet grill. After that, take a damp cloth to clean the stains of soot and ash on the cap and wall of smokestack on a pellet grill. Never wash the smokestack on a pellet grill with water as it will damage it with rust.