Taking a Closer Look at Replacement Hot Water Coils. (But not too close – they’re hot, folks.)

HOW A HOT WATER COIL WORKS

Hot water coils are heat exchangers made up of rows of tubes that pass through formed fins, which are bonded to the tubes via expansion. As cold air flows over the coil, it comes into contact with the heated fin surface, allowing heat to transfer from the hot water inside the tubes to the incoming air. This process is essential for efficient heating in HVAC systems.

Hot water coils serve a variety of purposes, such as energy recovery, reheating, preheating, booster heating, and general comfort heating. Their versatility makes them an important component in many commercial and industrial applications.

HOT WATER COIL DESIGN

Although all hot water coils operate on similar principles, their design and materials can vary depending on the application. Most commonly, they feature 1 to 3 rows of tubes, with standard construction using copper tubes and aluminum fins. Copper tubes come in various sizes, such as 5/8", 1/2", or 3/8". The water temperature inside the tubes can reach up to 200°F.

In environments where corrosion is a concern—like food processing plants—stainless steel tubes or fins may be used for increased durability. Some coils are designed with headers, while others, like booster coils, reheat coils, or heater core coils, do not have them.

Boosters are often used to reheat air that has cooled during its journey through ductwork, ensuring even heating across large spaces. In some cases, a collection header may be added to the opposite side of the coil, especially when replacing brands like Heatcraft™ or McQuay®.

Over the years, we've manufactured numerous custom and OEM replacement hot water coils—from small picture-frame-sized units to wall-sized models. Many of these have been quality replacements for top brands like Carrier®, Trane®, York®, and more.

SIZING A HOT WATER COIL

Replacement hot water coils are typically straightforward to match for proper fit and function. When measuring for a replacement, we check the fin height, fin length, and the number of rows. For new installations, we need details like CFM, entering dry bulb temperature, GPM (if available), and the desired leaving air temperature.

If you're taking your own measurements, our blank coil drawings page can help you record accurate specifications for your coil.

ORDERING A HOT WATER COIL IS EASY

Nationwide Coils offers a wide range of custom options and select stock sizes to meet your commercial and industrial heating needs. Whether you're looking for a replacement or a custom coil, we're here to help.

If you have any questions or need a quote, feel free to email us. Our team is dedicated to making your job easier and ensuring you get the right solution for your system.