Estimate heating coil output, required energy, electrical demand, fluid loads, and recommended design capacity using practical thermal formulas, conversions, efficiency, and safety margins accurately.
Altitude applies an approximate density correction using an exponential atmosphere model.
Common sensible heating uses:
Capacity corrections also include efficiency, heat loss, and safety margin.
Heating coil capacity describes useful thermal output over time. Engineers often express capacity in kilowatts or BTU per hour. The required value depends on flow and temperature rise. Fluid properties also influence the final thermal load. Air systems use airflow, density, and specific heat. Water systems use flow, density, and heat capacity. Electric coils convert electrical input into useful thermal energy.
Use the air mode for ducts and air handlers. Use liquid mode for water or glycol circuits. Batch mode handles a fixed fluid mass over time. Electric mode estimates capacity from circuit measurements. Steam mode uses steam flow and effective latent heat. Surface mode uses heat transfer area and LMTD. Each method represents a different practical design situation.
Real systems rarely deliver ideal theoretical performance. Coil fouling can reduce effective heat transfer. Insulation quality can also influence system losses. Efficiency corrects useful energy against supplied energy. Heat loss adds an allowance for unavoidable thermal losses. Safety margin provides capacity for changing operating conditions. Large margins should not replace proper engineering analysis.
Capacity rises when mass flow or temperature rise increases. Specific heat determines energy needed for each degree. Density converts volumetric flow into useful mass flow. High altitude reduces air density and heating mass flow. Glycol mixtures differ from water in key properties. Accurate property values improve every heating coil estimate.
The useful capacity represents the calculated thermal requirement. Design capacity includes efficiency and selected allowances. BTU and kcal outputs support common engineering references. Heating tons provide another familiar comparison unit. Operating cost uses estimated electrical input and energy price. Steam and surface calculations show equivalent electrical demand too. Good inputs produce reliable coil capacity estimates for planning.
| Medium / Method | Typical Property | Example Input | Typical Use |
|---|---|---|---|
| Air | Cp ≈ 1.006 kJ/kg·K | 2000 CFM, 20 K rise | Duct heating |
| Water | Cp ≈ 4.186 kJ/kg·K | 20 L/min, 40 K rise | Hydronic coil |
| 30% Ethylene Glycol | Cp ≈ 3.75 kJ/kg·K | 15 L/min, 30 K rise | Freeze-protected loop |
| Electric | PF often near 1.0 | 240 V, 30 A | Resistance heater |
| Steam | Latent heat varies | 100 kg/h, 2200 kJ/kg | Steam coil |
| Surface method | Q = UAΔTlmF | 75 W/m²K, 25 m² | Heat exchanger estimate |
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.