To calculate the overall wattage required you need to calculate the wattage for process startup, process operation and heat loss. (see also: Quick estimates for thermal wattage requirements)
In this first part we focus on the wattage required for process startup. Process startup requires quit often the most wattage, because the temperature difference (Delta T) and the heat up time are the biggest factors. Depending on application, (example: heat loss in fluid tank), other factors need to be taken into consideration.
Before you can calculate the needed wattage, you need to know:
Interesting links:
Here are a couple examples:
Metals:
How many watts are required to heat up 1 gallon (= 231 cubic in) of Steel, Aluminum or Copper in 1 hour based on a temperature difference of 100�F?
If the heat up time is decreased to 30 min, then twice the amounts of Watts are required. The efficiency of the heating method (conduction, convection, radiation) as well as the heater type will have a significant impact on power requirement and therefor operating costs. Typical heaters for the above applications are: cartridge heaters, band heaters, strip heaters and tubular heaters.
Water:
To heat up 20 gallons of water from 60 degF to 110 degF (delta T of 50 degress) you'll need 2400 watts. Water is best heated with immersion heaters or circulation heaters, custom heating systems or flexible heaters for wrap around drums or tanks. (example: freezing protection) For most water heating applications we do recommand the use of a mechanical stirring mechanism.
Air:
