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ExCoil

Hot water and glycol heating coils

Hot water heating coil design software

Size heating and reheat coils for air handling units. ExCoil calculates heating capacity, leaving air temperature, water temperature drop, velocity and pressure drop with the same row-by-row model used for chilled water.

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Calculator included in the free plan · The calculator interface is available in English and Portuguese.

3D model of a hot water heating coil with supply and return connections generated by ExCoil

Real application screenshot

What it calculates

  • Row-by-row counter-cross-flow heating model
  • Water or ethylene glycol mixtures
  • Physical tube count, circuits and passes
  • Water velocity and pressure drop with hydraulic warnings
  • Header and connection sizing with commercial pipe diameters

Results and deliverables

  • Heating capacity and leaving air temperature
  • Water outlet temperature, velocity and pressure drop
  • Air pressure drop
  • PDF report and 2D drawing (Professional); 3D, STL and STEP (Enterprise)

How the hot water model works

The coil is solved row by row with water entering at the air-leaving row. Water-side heat transfer uses VDI/Gnielinski, air side Wang–Chi–Chang with Schmidt fin efficiency, and the air–water energy balance is checked on every result.

  • Row-by-row counter-cross-flow marching
  • VDI / Gnielinski water side
  • Wang–Chi–Chang (2000) air side
  • Commercial pipe sizes for headers

Know the limits

  • Freeze protection and control valve sizing are not calculated.
  • Results are engineering estimates and must be reviewed by a qualified engineer.

Frequently asked questions

Can ExCoil size a reheat coil?

Yes. Enter airflow, entering air temperature and water conditions to obtain heating capacity, leaving air and water pressure drop.

Does the model warn about low water velocity?

Yes. Velocity and pressure drop are checked per circuit and flagged when they fall outside the recommended range.

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