The behavior matters
Does the heater fail to start, start without warming the water, or shut off after a short time? Those are different symptoms. Note what happens, any display message, and whether the pool or spa equipment otherwise appears to run normally.
If you know the heater brand, include it. If the display shows an error code, copy it exactly rather than translating it into a diagnosis.
Several systems can be involved
A pool heater depends on circulation, controls, and the heater unit itself. A professional may need to check more than one component to understand the cause. A visible error or shutdown helps point the inspection, but it does not confirm a failed part on its own.
A spa that will not heat may use different equipment or controls from the main pool. Mention whether the spa is attached to the pool.
When to call for help
If heating matters for an upcoming use, share your desired timing in the request. Availability varies, so avoid assuming immediate service. When a provider responds, ask about the inspection scope and any costs before work begins.
Gas and electrical equipment can be hazardous. Do not open the heater cabinet or attempt gas or wiring repairs. If you notice a gas odor, leave the area and contact the gas utility or emergency services.
Tell us the symptom and your location. We can use that information to consider an appropriate independent local provider. Availability is not guaranteed.
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