Heating Coil Selection Calculator for Electrical and Thermal Sizing

Input Data

Calculation Mode

Choose how required heater power will be estimated.

Airflow (m³/h)

Used only in airflow mode.

Inlet Temperature (°C)

Outlet Temperature (°C)

Altitude (m)

Corrects air density at elevation.

Known Heating Duty (kW)

Used only in direct load mode.

Supply Voltage (V)

Electrical Phase

Frequency (Hz)

Safety Factor

Typical range: 1.05 to 1.20.

Duct Width (mm)

Duct Height (mm)

Element Material

Target Surface Load (W/in²)

Lower values generally improve heater life.

Control Stages

Number of Coil Banks

Face Velocity Limit (m/s)

Example Data Table

Application	Airflow (m³/h)	Inlet (°C)	Outlet (°C)	Voltage	Phases	Material	Suggested Coil
Supply air duct	5,000	20	55	400 V	3	Nichrome 80/20	60 kW
Drying tunnel	8,500	25	80	415 V	3	Kanthal A-1	150 kW
Small process oven	1,800	18	65	230 V	1	Stainless Sheathed	18 kW

These rows are illustrative examples. Final selection should still be checked against enclosure temperature, controls, safety cut-outs, and manufacturer construction details.

Formula Used

1) Air heating duty:
Q = (ρ × Cp × V̇ × ΔT) / 3600

Where Q is heater power in kW, ρ is corrected air density in kg/m³, Cp is air specific heat in kJ/kg·K, V̇ is airflow in m³/h, and ΔT is temperature rise in °C.

2) Design duty with margin:
Q_design = Q_required × Safety Factor

3) Line current:
Single phase: I = P / V
Three phase: I = P / (√3 × V)

4) Required heated surface:
Area (in²) = Power (W) / Surface Load (W/in²)

5) Duct face velocity:
Velocity = Airflow (m³/s) / Duct Face Area (m²)

This tool gives a practical preselection. Final heater design still depends on detailed coil geometry, terminal arrangement, sheath temperature, air distribution, and control philosophy.

How to Use This Calculator

Select air heating duty if you know airflow and temperatures.
Select direct heating duty if process kW is already known.
Enter supply voltage, phase type, staging, and number of banks.
Choose the element material that best matches temperature and service conditions.
Set a target surface load. Lower values usually mean cooler elements and longer life.
Click Calculate Heating Coil to show the result above the form.
Review power, current, area, stage sizing, face velocity, and warnings.
Export the result to CSV or PDF for design records.

FAQs

1) What does this heating coil selector calculate?

It estimates required heater duty, design margin, current, equivalent resistance, heated surface area, staging, and a nearest standard coil size.

2) When should I use airflow mode?

Use airflow mode when you know the air volume and desired temperature rise. It is ideal for ducts, ovens, tunnels, and air handling systems.

3) Why is surface load important?

Surface load affects element temperature. High watt density can shorten life, increase sheath temperature, and create uneven heating risks in demanding applications.

4) Why can the selected coil be larger than required?

The tool rounds up to a standard capacity. That helps practical purchasing and control staging, but oversizing should still remain reasonable.

5) Does altitude affect the result?

Yes. Air density drops with elevation, so less mass flows at the same volumetric rate. That changes the heating power needed.

6) Can I use this for liquid heating?

Direct mode can help with known duty, but final liquid heater design needs fluid properties, flow behavior, wetted materials, and sheath compatibility checks.

7) What do stages mean here?

Stages divide total capacity into controlled steps. More stages improve controllability and can reduce overshoot during partial-load operation.

8) Is this enough for final procurement?

It is a solid preselection tool. Final procurement should confirm terminals, frame size, safety cut-outs, approvals, and manufacturer coil geometry.