Is a powered bottom necessary?

Is a powered bottom necessary?

A customer asks:

  1. What are the advantages of a powered bottom?
  2. Do the extra heating elements help the kiln get to temperature easier?
  3. I might have to make a choice between a powered bottom in a smaller (less tall) pull-apart Jupiter kiln or a non powered bottom in a taller pull-apart Jupiter kiln because of amperage limitations in my home.
  4. What do you recommend? 

Our answer:

  1. Powered bottoms are particularly useful for very dense loads like firing lots of tiles.
  2. The larger the bottom, and hence the larger the unheated surface area (especially in relation to the sides), the more an unheated bottom will affect the evenness of temperature. For instance a T3427 DaVinci kiln that is firing lots of tiles can really use a powered bottom. (By the way we find that even with such a kiln and load that the powered bottom is generally turned down to 50% of output).
  3. You generally do not need a powered bottom to enable the kiln to reach temperature. The exceptions to this are the 18" high JD23 and JD2918 which need extra power to heat up to Cone 10. However, you can always get an e23S or e28S kiln and be perfectly fine with heat up capability.
  4. A downside to powered bottoms is that ceramic chips, dust, etc can get into the element groves and cause trouble.
  5. If you were choosing between a powered bottom and an extra ring you will get more power as well as more space with the powered ring.