• Insulation loses its ability to slow the passage of heat when slightly moist.
  • Do not allow moisture to contact the insulation.
  • Use a moisture proof barrier between the pot and the insulation.
  • Use a closed cell insulation.

• The inner box will grow mold.
  • The inner surface should be easy to clean.
  • Cloth will become unsanitary if unprotected.

• To cook pinto beans
  • They need to be pre-soaked.
  • The retained heat cooker needs to be able to keep 5 liters of water above 90C for 90 minutes.

• Air exchanges are more important than insulation.
  • Make the enclosure as air tight as possible.
  • Use R-7 insulation at a minimum.

• The mass of the insulation and any mass within the envelope of insulation will rob heat from the pot of food unless the mass is above simmering temperatures.
  • Keep insulation and inner walls of the retained heat cooker as light as possible.
  • To work well insulation should not be less than R-2 per inch of thickness.
  • Full pots of near boiling temperature food retain more heat and cook food more effectively.

• Conduction loses more heat than convection. Convection loses more heat than radiation.
  • Lift the pot up off the floor of the box using a non-conductive material. Leave an air gap of one inch.
  • The walls and ceiling of the insulation optimally should be one inch bigger than the pot.

* Rule of Thumb: Wrong but works anyway