Freeze Sensor Installation

Auxiliary Freeze Protection should be installed on spas that are destined to be sold in cold climates. The hot tub manufacturer is responsible for the prevention of frozen pumps, plumbing and/or hot tub shell. Balboa Instruments will not be held liable for frozen hot tubs or hot tub equipment due to a misplaced or uninstalled auxiliary freeze sensor. The hot tub manufacturer must determine the appropriate location to install the auxiliary freeze sensors, usually the coldest location in the hot tub.

To Install an optional Freeze Sensor:

Turn off the power to the spa.

Locate the "Aux F" connector on the main system circuit board. It is generally near the main temperature sensor connectors.

Run the Auxiliary Freeze Sensor wire into the system enclosure using the same entry as the panel wire or other low-voltage conductors. Loosen the wire clamp with a screwdriver. The clamp can be removed to allow the wire to be installed into the system box.

Plug the connector into the Aux F output on the main Circuit Board and re-tighten the wire entry clamp. Be sure to capture any other wires that may also be held by the clamp.

Determine a plumbing location that is most likely to freeze in the even of cold weather. Possible locations could be:

Plumbing that is close the the cabinet:
Plumbing associated with a pump that does not run regularly.
Plumbing near the wet-end of a vulnerable pump.

It is up to the manufacturer to decide the most appropriate location for the Auxiliary Freeze Sensor in a given model.


Use zip ties to install the sensor in direct contact with the vulnerable plumbing.

Insulate the back of the sensor with a small amount of spray foam (1.75 - 2.0 pounds per cubic foot) so it will not be affected by air temperatures in the equipment compartment. Do not insulate the entire pipe diameter.