A pool heater or a pool pump is a vital component of the swimming pool. It keeps the water flowing through the filter making sure your pool is free from all kinds of debris. The heater also maintains a circulation current in the water to prevent algae formation.

There are several reasons for a pool heater to shut off randomly. This behavior is called pump tripping. Here are some common causes:
Incorrect Voltage
Incorrect voltage is one of the common reasons why a pool heater shuts down. The heater’s motor runs off 115 or 230 volts. Sometimes, a heater can be wired incorrectly causing it to trip every 5 to 10 seconds. A bad capacitor may also be the culprit. Another thing that may reduce the voltage of the pump is loose wires. Call a licensed electrician to inspect your pump for wiring.
Impeller Obstructions
Pool heaters use a spinning impeller to suck water from the filter. If the impeller is stuck, the heater starts humming and shuts off automatically. Check for debris such as leaves, rocks, insects, or pieces of clothes stuck in the impeller. This might be hindering the movement.
To free the impeller, you will have to take the pool heater out. Call a professional if you don’t know how it’s done.
Pump Overheating
Most pool heaters are designed to shut off automatically when they start overheating. Thermal overload switches perform this task. If your heater is shutting off continuously, it is likely the thermal switches need replacement. It is also possible that the pump is overheating. Call in a technician to determine the cause and solve the issue. If you are not familiar with how the switches work, don’t troubleshoot the pump yourself.
Poor Priming
Sometimes, the pool heater hasn’t actually shut off, lack of flowing water is giving an illusion that it’s off. If that’s the case, the heater needs priming. It’s the process of allowing water to flow through the pump and the filter of the pool.
Excessive Energy Consumption
If your pool heater has shut off on an extremely hot day, it’s a sign the pump failed to get electricity from the grip. During summer, people are running their AC units more than ever along with other appliances. This may drop the power. If that’s the problem in your local area, you will have to wait until the power is restored. Call your local power company for verifying the power shortage in your area.