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

Winter is here, and with it comes a flood of service calls about frozen water coils. One recent job at a New York City condo complex brought us to a Dunham-Bush® unit that had suffered serious damage — the water inside had frozen, causing the u-bends to rupture.

This particular unit featured a 2-row hot water coil and a 4-row chilled water coil, both using 5/8" copper tubing. The unit was located in an area that relied entirely on outside air, meaning it was the first to be exposed to extreme cold when the dampers were open. Normally, a freeze stat would detect temperatures below 32°F and trigger the dampers to close. Unfortunately, in this case, the freeze stat was faulty, leaving the dampers open and allowing the water to freeze. As water turns into ice, it expands by about 9%, which led to the coil rupturing.

To Repair or Replace? That is the Question.

In this situation, we opted to replace the entire coil. However, not all cases require a full replacement. In many instances, a damaged coil can be repaired using brazing — a process where two metal pieces are joined by melting a filler metal. Whether you choose repair or replacement depends on several factors:

• Accessibility: If the u-bends are on the back of the coil, they’re easier to braze than if they're on the front.
• Urgency: For critical units that need to stay operational, brazing offers a quick and cost-effective fix. If time isn’t an issue, ordering a new coil might be better.
• Age of the coil: Older coils may not be worth repairing long-term, especially if they’ve been through multiple issues.

If you're dealing with a water coil or any other type of coil that's showing signs of damage, give us a call. We offer custom and OEM replacement coils for every make, model, and year — whether your coil is frozen or just needs a little TLC.