Ventilation in Kilns

Ventilation in Kilns


  1. Get a Vent-Sure Kiln vent with your kiln
  2. Install the vent to an outside wall
  3. Make sure you have enough ambient ventilation for the heat


Fumes are harmful gases that are produced when using certain materials in the kiln, such as carbon in clay, china paints, and glazes containing oils, or when using decals or other miscellaneous products. These fumes can include carbon monoxide, sulfur oxides, hydrogen fluoride, and metal vapors, and can be harmful to your health. It is important to properly ventilate your kiln room to prevent the buildup of these fumes.

For the Health of the Kiln

  1. An electric kiln that has plenty of oxygen will help extend the lifespan of elements and thermocouples.
  2. The materials used in L&L kilns thrive in an oxygen-rich environment.
  3. Using the Vent-Sure Downdraft vent system can help increase the warranty on your kiln's elements.

Three kinds of kiln ventilation

  1. In the past, people used to vent their kilns by propping open the lids and creating peepholes during the ceramic firing process. You can still do this if you wish, but make sure you have proper room ventilation to remove any fumes that may be released into the room.
  2. We recommend using the VENT-SURE downdraft kiln vent system. This system will vent the fumes from the kiln, help cool the kiln, improve the uniformity of firing, and maintain the oxygen level in the kiln (which is important for certain glaze effects).
  3. Some people use hood-type vents where a hood sits over the kiln and vents heat and fumes. However, without a vent pulling fumes directly from the kiln, the kiln atmosphere is not constantly refreshed.

General Room Ventilation (for fumes and heat)

  1. Do not operate the kiln in an enclosed space without the right ventilation.
  2. Ventilation is important for removing the fumes from firing and preventing heat build-up, which can be a fire hazard.
  3. Aim for room ventilation of at least 10-25 times the cubic feet of the kiln per hour. For example, if your kiln has a volume of 10 cubic feet, you should aim for 250 cubic feet of ventilation per hour (about 4 cubic feet per minute).
  4. How to calculate ventilation requirements for removing heat from a kiln room

Vent-Sure Kiln Downdraft Vent System

How a Downdraft Vent Works

  1. The downdraft vent system works by pulling air from tiny holes in the bottom of the kiln, which creates a slight negative pressure inside the kiln. This helps to draw in just enough fresh air to continuously replace the air being removed.
  2. The heat in the kiln is forced to circulate, and the slight downdraft effect of the vent system helps to counteract the natural tendency of heat to rise in the kiln, resulting in more even temperatures top to bottom.
  3. The number of holes required will depend on the size of the kiln and can range from 1/4" to 5/16". Too many holes can cause slower firings and a lower maximum temperature, and the vent system ductwork may get too hot and potentially melt if there are too many holes. The Bypass Collection box (included with the Vent-Sure vent system) allows you to adjust the amount of air being removed from the kiln.
  4. Keep in mind that the amount of air being removed from the kiln decreases as the temperature increases, as the air inside the kiln expands with temperature. The best vent systems may not be able to handle large amounts of smoke or wax resist and still allow the kiln to reach its highest temperature.
  5. To ensure that you have not created an unsafe situation, you should check the temperature of the flexible ductwork while the kiln is at its maximum temperature. Most flexible aluminum ductwork is rated for at least 350°F, so if it is hotter than the rating you should plug up at least one hole using high-temperature cement or other high-temperature fiber products.
  6. Be careful if you are using wax resist, as the wax may condense on the inside of the aluminum ductwork, which could be dangerously flammable. You should check this periodically and clean the fan motor and inside of the ductwork to remove any residue, particularly wax resist.

Do you need a Vent Control?

  1. A vent control system lets you set the vent to turn on or off during different stages of the firing process.
  2. This gives you more control over the firing and allows you to reduce the amount of air vented from the kiln and the room.
  3. Most fumes are produced at specific times during the firing process.

Can you vent two kilns with one vent?

  1. One vent can handle up to 20 cubic feet of kiln capacity so you could vent two 10 cubic feet kilns (two e28T-3 kilns for instance) with one vent.
  2. You can purchase a Vent Doubler to do this.

Do you need holes in the lid?

  1. L&L does not recommend adding air-intake holes to the lid of sectional kilns, but you can do so if you prefer.
  2. If your kiln is not sectional or fits together very well, you may want to consider drilling air intake holes in the lid.
  3. The number and size of these holes should never exceed the number and size of the air exhaust holes.


From Jessica Putnam-Philips:

Yes, you can install a kiln vent. If I can do it you can do it! In this video, I walk you through all the steps to safely install the kiln vent.

  • Tools and Materials:
  • Kiln Vent Kit
  • Flat Head Screwdriver
  • Phillips Screwdriver
  • Electric Drill with 1/4" bit
  • Yard Stick
  • Pencil Work
  • Gloves
  • This video shows how to drill your kiln bottom for a Vent-Sure ventilation system in case you are installing on a new kiln or if your holes are not already predrilled. The number and sizes of holes can be determined by looking in the vent instructions.