Calculating ventilation requirements for heat from a kiln room

Calculate how many CFM of air ventilation you need

  1. Find the BTUs per hour (BTU/Hour) your kiln produces. Check the BTU chart on the General Dimension Drawing for your kiln model.
  2. You can download the General Dimension Drawing from the web page for that kiln model. (See item #3 below for Easy-Load kilns).

    kiln page buttons
  3. You will find a chart like this on the drawing:
    BTU Chart
  4. For Easy-Load kilns use the chart found in this PDF.
  5. Use the BTU/Hour number for the highest firing temperature. You can extrapolate these numbers. For instance, you can pick a BTU/Hour number between the column for 2232°F and 2350°F for Cone 8 firing.
  6. Keep the room temperature at 120°F or below. Determine the typical highest outside temperature.
  7. Calculate the temperature difference (Delta T) between the room and outside temperatures.
  8. Use this formula: BTU/Hour / (1.085 x Delta T) = CFM (cubic feet per minute).

An Example

For an e23T-3 kiln firing at Cone 6: 16,104 BTU/Hour.

  1. Delta T: 120°F - 100°F = 20°F.
  2. Ventilation needed: 16,104 / (1.085 x 20) = 742 CFM.
  3. Ensure sufficient makeup air enters the room to prevent high static pressure, which reduces fan efficiency.  This will keep the static pressure to a minimum. An increase in static pressure will downrate the rated CFM of a given fan. 

Sizing an HVAC System

  1. You can use the same BTU information to size your HVAC system
  2. One ton of cooling capacity equates to 12,000 BTUh. 
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