5 Key Components to Troubleshooting a Pressure Switch

5 Key Components to Troubleshooting a Pressure Switch

by Mark Zalewski

Understanding the myriad of components that make up a hot tub remains a daunting task for many homeowners. Yet the more you know, the better you can anticipate and protect against costly breakdowns. Here is a useful introduction to the world of troubleshooting and calibrating a hot tub pressure switch.

The Big Picture

The pressure switch's job is to shut down the heater if the pressure within the circulation system falls below a certain threshold. If it didn’t, and the heater was allowed to remain running, the rising temperature would eventually expose the components, the pipes, and even parts of the hot tub itself to risk of damage or degradation. Such low flow scenarios are generally indicated on your control panel by an error code such as FLO, FLC, or OH.

Flow Problems

Obstructed Suction Ports

There are a number of scenarios that can trigger the pressure switch to shut down the heater. Perhaps the most common reason is that something is obstructing the flow of water out of the hot tub. Thus the first thing you should do when faced with a flow-related error code is to ensure that the suction ports are not being blocked by any foreign debris. You will generally find these ports located along the bottom walls of the hot tub. Water is also drawn in through the skim filters located higher up; ensure that these are also unobstructed.

Dirty Filter

The next most common reason for a pressure switch to trip the heater is a filter that has become excessively choked with debris. This will slow the movement of water through the circulation system, eventually restricting the flow to the point that the pressure reaches the critical threshold. Fortunately, this is a fairly simple problem to remedy. All you have to do is give your filter a thorough cleaning.

Air Lock

If cleaning your filter still does not restore proper functionality to your hot tub, it may be the case that you are dealing with an air lock. This frustrating problem generally occurs after having drained a hot tub for cleaning. The problem is that, when you fill the tub back up with water, air may have become trapped inside the supply lines. This problem is easily recognized by the fact that, though you hear your pump functioning, no water will be flowing into or out of the system. You may attempt to purge the air lock yourself--just be aware that, if the problem remains too stubborn, you may need to enlist the help of a professional.

Pressure Switch Problems

If none of the above seem to be the case, it is important to realize that the problem may lie with your pressure switch itself. Such problems can take one of two forms: a faulty pressure switch, or a miscalibrated pressure switch.

Faulty Pressure Switch

The Balboa 30408 pressure switch, for example, is able to gauge the pressure of the water inside the circulation thanks to a tiny 1/8” hole in its side. This hole allows water into the switch, which is then able to measure its pressure. Unfortunately, this hole often becomes blocked by debris or mineral deposits. Such deposits are generally the result of bad water chemistry. Unless the pH is properly monitored, and kept within the correct range, the problem will likely recur again down the line. A faulty pressure switch may also be caused by corrosion or overheating of the wires that connect the pressure switch to the hot tub’s heater.

Miscalibrated Pressure Switch

All pressure switches are equipped with a small adjustable thumb wheel, which can be used to make changes to the switch’s calibration. In other words, this wheel adjusts the amount of pressure needed to trigger the switch. Be aware that calibrating a pressure switch is generally not considered an appropriate task for an amateur, as dialing in the right setting takes a lot of experience. Thus it is best to contact a professional to help ensure that your switch is appropriately calibrated.