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Home TechTime December 2016 Electric Heaters
TechTime is a Neptronic publication aiming to inform you on the best ways to deal with common issues highlighted by our technical support team. Each edition features three new topics and will be posted on neptronic.com.

Plug It In
Using Heater Selection Formulas

At times when designing or selecting a heater, the schedule/specifications may not include all the details you need. This article will help calculate the missing details/information to complete the selection process.

The basic information required when selecting a heater is: (a) VOLTAGE/ph/Hz; (b) Power in kW; (c) DUCT DIMENSIONS; (d) AIRFLOW. If one of these details is missing, the process of selecting and ordering a heater is incomplete.

  • (a) Neptronic heaters are custom built as per your selection. If you do not know the voltage – do not assume. Please find out the correct voltage before submitting a selection. If the current in amps (I) is provided, the kW can be calculated using the formula below. Note that the voltages are with +/- 5% tolerance. Using wrong voltages could damage the heater.

  • (b) Often you may not see the power (kW) listed on the schedule. Airflow and temperature rise (Delta T) are required to calculate the kW. Information could be provided in Imperial or Metric format. Pay attention to plug in your values in the correct formula.

  • (c) Dimensions are very important to manufacture a heater. Our heaters are custom built to fit any duct size but cannot be field modified if actual duct dimensions are different. Duct area can be calculated using below formulas, but this will only provide a minimum duct size in square feet or square meters based on your kW.

  • (d) AIRFLOW plays an important role in the selection. Neptronic’s heater software selects the appropriate type of heating element (gauge/quantity) based on the airflow that is entered. The same formula used to calculate kW can be used to estimate airflow.

Here are some conversions that may help for quick calculations;

These formulas are there to help you when selecting electric heaters. Use them to your advantage!