Steam Coils Vs. Hot Water Coils

Steam and hot water coils are used to heat air for residential and commercial ventilation applications. They are typically controlled by a valve on the heating supply line and/or a damper motor (a motor that controls movable plates that, in turn, regulate flow).

Steam

A steam coil employs a device known as a steam trap to capture all the latent heat -- the heat absorbed during a change of phase -- of the steam. The correct trap must be used to prevent condensation, which can cause reduced coil output, corrosion and failure.

Hot Water

Hot water coils are used in comfort heating applications and typically have a maximum of three rows of tubes. The tubes are connected to the hot water flow and returns mains, but there must be enough connections to ensure even distribution of water throughout the coil.

Considerations

A hot water coil must achieve maximum heat efficiency with minimum drop in air pressure. The drop in water pressure from one side of the coil to the other must be as low as economically possible.

References

• "Industrial Ventilation Design Guidebook"; Howard D. Goodfellow, Esko Tähti; 2001
• "Good School Maintenance"; Illinois Association of School Boards; 1996