Pool Heater Repair

A pool heater that won’t heat, or won’t hold temperature, is one of the most common reasons a pool “feels wrong.” The good news is that heater problems usually come from a short list of components, and diagnosing which one is the point of the repair. Gas and electric heaters fail in different ways, but both follow a pattern you can trace.

The symptoms

• No heat at all. The heater runs but the water stays cold. Usually an ignition, gas-supply, or electrical issue — the heater is trying to light and can’t, or isn’t getting the signal to.
• Heats, then stops. Short-cycling heat is a sensor or flow issue — a flame sensor, a flow switch, or a thermostat cutting the heater off. It’s almost never the heat exchanger failing.
• Error codes. Most modern heaters tell you exactly what they think is wrong. A code is a starting point, not always the final answer, but it narrows the diagnosis fast.
• Temperature drifts down. The water warms, then slowly cools despite the heater running. Often a gas valve, a sensor, or a flow restriction the heater is fighting against.

Gas heater repair

Gas heaters have a small set of heat-related components, and most no-heat problems live in one of them:

• Igniter — the component that lights the gas. A tired igniter is a very common no-heat cause.
• Gas valve — controls gas to the burner. A failing valve is a classic short-cycling and no-heat culprit.
• Flame sensor — confirms the flame is there. A dirty or worn sensor makes the heater shut off.
• Thermocouple / controls — the safety and control side that keeps the gas valve open only when it should be.

Electric heater repair

Electric heaters are simpler — heat elements and the electrical components that drive them. The common failures:

• Heating elements — they burn out over time, especially with hard water. A dead element is a straightforward replacement.
• Contactors and relays — the electrical switching that turns the elements on and off. A failing contactor is a common cause of a heater that won’t engage.
• Wiring and connections — heat and cycling take a toll on connections over time.

What the diagnosis checks

Before any part is touched, the diagnosis confirms the basics: Is the heater getting power? Is there adequate flow (a heater with no flow will shut itself off as a safety)? Are the sensors reading correctly? Is the gas actually reaching the burner (for gas units)? Walking through that sequence is what separates a real repair from swapping parts in the dark.

Frequently asked questions