Recently we have had questions about using a PolyScience chiller for temperature control of an external tank. Here are some options for doing this:
You can create a cooling coil for the inside or outside of your tank through which the heat transfer can occur. The coil will act as a heat exchanger for your external tank. The coil can be made of any material with good heat transfer properties. It may be wrapped around the outside walls of the tank, looped across the bottom of the tank or formed into a coil which can be submerged in the tank. If the coil is on the outside of the tank, insulation will help to pervent heat gain or loss.
Whether the coil is inside or outside the tank, it is important to have circulation inside your tank to ensure uniform temperature by moving the fluid past the cooling coil. A mechanical stirrer or submersible pump may be used.
Since this is a closed circulation loop, you will not need to make changes to the chiller settings for it to work.
A second, popular, option is to place your tank at least two feet above the chiller. Connect tubing between the chiller and the tank. Be sure the line from the tank to chiller inlet port is as straight as possible to allow maximum gravity flow back to the chiller. If there are bends or dips, it will slow the return.
Since the pump will push out more fluid than the gravity feed will return to the chiller, you will need to install a ball valve to regulate the outlet flow. You may also need to adjust the low flow setting to prevent low flow alarm from occurring.
Once all of this is in place, you will need to work with the system until you balance the outlet and inlet sides. You may also need to continue to fill the chiller reservoir. As it gets empty, continue to add fluid until the fluid starts returning to the reservoir. If the chiller is allowed to run with no or very low fluid, the reservoir and/or pump may be damaged.
If you want open loop circulation to your external tank (meaning not using a cooling coil), then we recommend purchasing a chiller without a reservoir. The external tank becomes the reservoir so you do not need to worry about low fluid settings and alarms on the chiller.
If you know you will be running your chiller with an external tank, please tell your distributor or PolyScience rep, so we can ensure you purchase the best chiller configuration for your needs.
One more note; it is difficult to make all the changes to remove the reservoir once you have purchased it. If your needs change, and it would be helpful to have the reservoir removed, contact your distributor or PolyScience rep.