Site Bite: Ruptured U-bends in a Frozen Water Coil

Winter brings its fair share of challenges, and one of the most frequent calls we receive during these colder months involves frozen water coils. Recently, we visited a condominium complex in New York City where a Dunham-Bush® unit experienced a freeze-up, leading to burst u-bends. Upon closer inspection, you could clearly see the fractures in the u-bends.

This specific unit featured a 2-row hot water coil and a 4-row chilled water coil, both constructed with 5/8" copper tubing. The unit’s location meant it relied solely on outside air, making it the first to encounter freezing temperatures when the dampers were open. Ideally, the freeze stat—a temperature sensor in HVAC systems—would have triggered the dampers to shut when the temperature dipped below 32°F. Unfortunately, this freeze stat was malfunctioning, leaving the dampers open and allowing the water inside the copper coils to freeze. When water turns to ice, it expands by about 9%, causing significant stress on the coils and eventually leading to their rupture.

To Repair or Replace? That is the Question.

In this scenario, a brand-new coil was ordered. However, ruptured coils often have the option of being repaired through brazing, which involves joining metals by melting a filler material into the joint. Whether to repair or replace a coil depends on several factors:

• Accessibility: It's easier to braze damaged u-bends located at the back of the coil rather than those on the front.
• Importance of the Unit: If the coil is critical and must function daily, brazing offers an immediate and cost-effective solution. Ordering a new coil provides an alternative if time isn’t a pressing concern.
• Age of the Coil: The coil’s age plays a role; replacing it might be the better long-term choice if it has been in service for many years.

Are you dealing with a water coil or another type of coil that requires replacement? Email us for a quote. We specialize in manufacturing custom and OEM replacement coils for any unit, regardless of make, model, or year—even those affected by freezing temperatures.