Avoiding Burst Coils

It is not uncommon for buildings to be heated and cooled out of a building central plant. The central plant makes hot or cold water that is piped around the building. There is a common point of failure that can cause substantial damage to the building and its contents. That risk can be mitigated when the people maintaining the air handlers are made aware of the potential situation.

Normally, in areas that experience cold weather, the central plant only operates the chillers to provide cooling when the temperature outside is above a set point.? If cooling is needed when it's cooler outside, outside air is brought in to cool the space. That presents the potential point of failure. If freezing outside air is allowed to enter the water-filled coil, the coil can freeze and burst.

When a coil freezes and bursts, there is the potential for a lot of water to flow from the unit. In a worst-case scenario, the flood can destroy a store, and the space below it when it happens at night. There are several potential reasons for why freezing air would be allowed to enter the water-filled coil.? ? ?

• Dampers can freeze in place if not lubricated. The controls can fail leaving the dampers fixed in place.? ?
• ?Sensors can be installed in the wrong place; controls can be adjusted badly and, in some cases, disconnected altogether.? ? ?
• Freezestats are installed to protect against these potential problems. However, they can be installed in the wrong place or set improperly. Technicians can reset tripped freezestats and put the unit back into service without resolving the problem.

Another not-common problem is that there are units installed with no mixing box. A mixing box is where the outside air is mixed with return air to maintain a return air set point well above freezing but cool enough to cool the space. When there is no mixing box, freezing outside air can enter the coil unmixed and freeze the coil. This problem is made worse by the fact that moving these pieces, once installed, is unlikely to be done.

The only practical solution to any of these problems becomes either locking-out the outside air or draining the coils of the water for the winter or until the problem is resolved. It takes a skilled and informed workforce to reliably detect these issues and react to them appropriately. The result of failing to do so can be disastrous.

Make sure you avoid coil bursts, contact #HeliosServicePartners. Please DM us or email [email protected].

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