Heating Coil Calculator

Heating coil capacity and outlet temperature calculation. Regeneration heating sizing.

What is the Heating Coil Calculator?

The heating coil calculator determines the capacity and outlet air conditions of heating coils in air handling units. It produces sizing output for post-cooling reheat, desiccant rotor regeneration heating, winter air preheating and process air conditioning applications.

Heating is sensible heat transfer: humidity ratio (W) remains constant, only dry-bulb temperature and relative humidity change. The calculation formula is Q = ṁ × c_p × (T_outlet − T_inlet). Outlet relative humidity is calculated from the constant humidity ratio and saturation pressure at the new temperature; this reveals whether outlet RH drops below the 30% comfort threshold.

Heater type selection (electric, hot water, steam) is driven by energy infrastructure and capacity. Electric coils are preferred for small capacities (<50 kW) and precise control, hot water coils for large HVAC systems, steam coils for industrial high-capacity applications. The tool automatically calculates hot water flow (Δt = 80°C/60°C standard) and steam consumption (3 bar / 5 bar standard).

NKT engineering uses this calculation for silica-gel rotor regeneration heating capacity, freeze-dryer pre-conditioning, lithium-ion dry room make-up air post-heating, and winter pre-heating in AHU design. When outlet RH falls below 30%, adding a steam humidifier downstream is recommended.

Applications

• Desiccant rotor regeneration heating
• AHU heating coil sizing
• Lithium-ion dry room make-up air heating
• Freeze-dryer pre-conditioning
• Reheat-then-humidify staging
• Winter air preheating
• Process air heating
• Hospital and pharmaceutical HVAC heating

Articles related to this calculator

In-depth content to support your engineering decision after completing the calculation.

Technical Article

How to Calculate Humidification Capacity: A Step-by-Step Guide for Field Engineers

A step-by-step explanation of the capacity calculation that must precede humidifier selection: required inputs, RH-to-absolute conversion, outdoor-air impact, steam vs adiabatic decision and common sizing mistakes.

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Technical Article

What Is a Steam Humidifier? How Electrode and Resistive Systems Work

Definition, applications and core advantages of steam humidifiers; how electrode (Joule heating) and resistive (Incoloy immersion) architectures work, their structural difference, application matching, water-quality impact, and steam distribution / absorption distance design.

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Technical Article

The Importance of Industrial Humidity Control, A Decision Guide for Production Managers

In Türkiye, indoor relative humidity drops to 20–30% for 5 winter months; static electricity reduces production efficiency, product stability shifts, and employee absenteeism rises. Hygroscopic regain table, ROI calculation, sector-specific costs, and a Neptronic equipment selection guide.

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Technical terms used in this tool

Access concise ASHRAE-referenced definitions of technical concepts you encounter in the calculation.

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