Chilled Water vs. Hot Water Coils: What's the Difference?
Commercial chilled-water and hot-water HVAC coils appear almost identical on the outside; however, they are more different than most people think. Both are water-based heat transfer components, but they work opposite each other and are better for different applications. Here is a full breakdown of the differences between chilled water vs hot-water coils, and how to decide which to use for your application.
The central difference between chilled water and hot water coils is heat transfer and operation. In a chilled water coil, warm air enters and passes across the coil, which contains chilled water flowing through the tubes. As the air passes through the coil, heat transfers from the air to the water, which then produces cooler air that leaves the coil. After the cooled air leaves the coil, the warmed water returns to the chilled water system to be cooled again, and the process repeats. In addition, chilled water coils can condense moisture in the air when temperatures fall below the air’s dew point.
In a hot water coil, the heat transfer works opposite the chilled water coil. Cool air enters and passes across the coil, which contains heated water flowing through the tubes. As the air moves through the unit, heat transfers from the water to the air, producing heated air leaving the coil. The cooler water then returns to the heating system, and the process repeats. The chilled water coil’s heat transfer is air to water, whereas the hot water coil's heat transfer is water to air.
Because of the difference in heat transfer, chilled and hot water coils experience some different issues when it comes to failure. While both chilled and hot water coils can experience corrosion, leaks, and fouling, chilled water coils experience freezing, while hot water coils experience high-temperature thermal stress that deteriorates material. Understanding why a chilled water coil has failed as opposed to a hot water coil can make all the difference in downtime for your replacement job.
In terms of application, selecting either a hot water or chilled water coil fundamentally has to do with whether you want to heat air up or cool air down. Both chilled and hot water coils take into account similar variables for replacement jobs, such as airflow, entering air/water temperature, and sizing, to name a few. While physical dimensions are important for replacing water coils, replacement jobs are so much more than that, which is why you need a company that can help you get precisely what you need for your system.
Whether you need a chilled water or hot water coil replaced, HeatEX Technologies is here to assist. Supplying a wide range of coils from water to DX, we have crucial industry expertise combined with excellent customer service that elevates your replacement project by reducing downtime and unnecessary spending. The next time you need a coil or heat exchanger replaced, give HeatEX Technologies a call, and let our team help you find the right solution for your system.
