Pool heater repair: what to know

What the job involves, what changes the price, and what to ask a pro.

What pool heater repair is

Pool heater repair fixes a heater that will not ignite, shuts off during use, cycles on and off too often, leaks, or does not reach the set temperature. Most calls come in during the season, when the pool needs heat and the heater stops working.

Signs you need it

  • The heater will not light, or it lights and then goes out within moments
  • The heater shuts off and shows a fault code on its display
  • Water leaks from the heater, its bypass valves or the drain plug
  • The pool does not reach the temperature you set, or the heater runs nonstop
  • You smell gas, see soot, or notice a scorched or rusted heater housing

What the pro does

  • Check the gas supply or power supply, the heater controls and any safety switches
  • Test the pressure switch, flow switch and thermal cutoff for proper operation
  • Check the ignition system, including the igniter or electronic ignition module and the flame sensor
  • Inspect the heat exchanger for scale, cracks, rust or blockage, and check the water flow through it
  • Replace the faulty part, such as the igniter, flame sensor, pressure switch, gas valve, temperature sensor or heat exchanger
  • Start the heater, confirm the temperature rise and check every connection for leaks

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Heater type and age, since older units may need parts that are no longer made
  • Which part has failed, such as an igniter, sensor, switch, valve or heat exchanger
  • Gas or electrical work needed to restore safe operation, including line checks and shutoffs
  • Access to the heater, including how it is mounted and how much plumbing must be opened
  • Whether the heat exchanger can be cleaned or must be replaced
  • Water flow problems from the pump, filter or valves that make the heater shut off
  • How far the parts supplier is from the job, which affects how fast the part arrives

What a written quote should spell out

  • The fault found and how the pro confirmed it with a test
  • Each part to be replaced, listed by name and part number
  • Gas or electrical work listed separately for the licensed trade doing it
  • Whether the heat exchanger is cleaned, repaired or replaced, and why
  • Start-up and test results after the repair, including the temperature rise
  • Warranty on the parts and labor, and what happens if the fault returns

Questions to ask before you hire

  • Which part do you think failed, and how did you confirm it?
  • Can the heat exchanger be cleaned, or does it need to be replaced?
  • Do you check the gas pressure or the electrical supply during the repair?
  • Are the parts new or used, and what warranty do they carry?
  • If the heater is old, do you recommend repair or a new unit, and why?
  • Will you check the water flow and the filter before you blame the heater?

Red flags

  • They replace the heater without first testing the igniter, sensor and switches
  • They will not show you the fault or the test results
  • They work on gas lines without a licensed trade where one is required
  • They skip the flow check before calling the heat exchanger bad
  • They quote a new unit without explaining what the repair would fix

What you can do yourself

A homeowner can check that the pump is running, the filter is clean, the valves are open for flow, and the heater's power or gas supply is on at the usual switch or valve. Do not open the heater, touch the gas valve or igniter, or work on the wiring, because those parts can leak gas or shock you. If you smell gas, leave the area and call your gas utility, and call a pro for every heater fault.

Licenses and permits

Pool heater repair often involves gas or electrical work, which commonly requires a licensed trade, and some repairs may need a permit. Check with your state or local licensing agency to see which licenses and permits apply to your heater and the work.

Pool heater repair questions

Why does my pool heater keep shutting off?

Low water flow is a common cause, from a dirty filter, a clogged basket or a closed valve. Other causes include a failed flow or pressure switch and a faulty sensor, so a pro should test those parts before anything is replaced.

Is it worth repairing an old heater?

It depends on the heater's age, whether parts are still available, the cost of the repair compared with a new unit, and the condition of the heat exchanger. Ask the pro to explain the trade-offs in writing.

What should I do if the heater smells like gas or shows soot?

Gas smell or soot is a safety problem. Leave the area, call your gas utility, and have a pro inspect the heater and its gas connections before it runs again.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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