Water coils should have a vent at the high point and drain at the low point. Nortek coils are produced with either 1/8”, 1/2” or 3/4” vent and drain. These options make no difference if the coil is not built correctly.

Water coils should be circuited (return bend arrangement) to gravity drain. The typical water coil is designed for horizontal airflow, as shown here. Let us know if you have the rare coil that lays on its side for Vertical airflow. These can be circuited to drain. The key is to let us know what you need.


To allow draining, coils must be mounted level end-to-end (or the tube length of the coil). The return bends must be placed on the coil in a specific pattern. First, they must match the coil serpentine for the desired water velocity for the coil performance needed. Second, they must provide a path for the water to flow to the low point and exit the drain.

In this sketch are simple patterns to illustrate how return bends are placed to allow water to drain.  You can see how the tubes are connected to provide level or downward water flow to the drain. This is not always the most straightforward method for manufacturing, but it must be done properly

To simplify this process, some coils are manufactured as shown in this sketch. You can see the water has no downward path to drain. If you have purchased a coil with a pattern like this, your coil will not drain.

There are always exceptions to every rule. We note these on our coil performance as follows: “Coil will not gravity drain for standard horizontal air flow position.” This exception is for very low water flow, requiring a low serpentine value. When you see this note, this is necessary to maintain the predicted coil capacity. 

Lead Times

  • Standard Production:
    Orders are scheduled to ship by the fourth Friday after the released PO is received
  • Quick Ship:
    2 workday production – add 100%*
    (Contact factory to confirm material availability.)
    5 workday production – add 50%*
    10 workday production – add 25%*
    *Minimum add per coil $100
    Minimum PO amount $500

As a reminder, in the current state of the world, all manufacturers face supply chain challenges obtaining materials for production. The following are the current challenges we face in the coil market:

We will continue to keep you updated on the current state of the coil market. We thank you for your understanding as we navigate these market challenges and for your continued business.

Need something that’s a bit different than a standard coil? No problem! We will work with you to meet your needs.

Have additional questions? Make sure to give Swan a call!