Pool heater maintenance checklist
Updated August 2026
The single most important thing for a pool heater is keeping the water balanced, pH 7.2 to 7.6, so scale never forms on the heat exchanger. Past that, a gas heater wants a yearly burner and vent cleaning, and a heat-pump model wants clear coils and airflow. Low pH and hard scale are what destroy heat exchangers, and they decide whether a gas heater dies at 5 years or reaches 10, or a heat pump reaches 20.
| Task | Interval | Effort |
|---|---|---|
| Hold pH 7.2 to 7.6 and calcium in range to stop scale | Ongoing | 5 min · DIY |
| Task | Interval | Effort |
|---|---|---|
| Clear the burner tray, check the vent, look for spider nests | Yearly | $150–300 pro |
| Task | Interval | Effort |
|---|---|---|
| Rinse the evaporator coil and clear leaves and airflow | Yearly | 20 min · DIY |
| Inspect the heat exchanger and fittings for scale or leaks | Yearly | 15 min · DIY |
| Task | Interval | Effort |
|---|---|---|
| Drain and winterize the heater in freeze climates | Fall | 30 min · DIY |
What neglect costs
Scale is the silent killer. Water that runs too hard leaves a mineral crust on the copper heat exchanger that insulates it, so the heater burns more fuel for less warmth and eventually overheats and splits, a $500–1,500 exchanger on its own. Water that runs too acidic is worse, corroding the same copper thin in a single season. When the core is gone, you are usually into a full replacement: a gas heater runs $2,000–4,500 installed and a heat pump $3,000–6,000, which is why the pH test is the cheapest insurance you own.
Leave these to a pro
Balancing the water is yours; most of the rest of a gas heater is not. Combustion, gas pressure, venting, and ignition on a gas unit are pro territory, and a yearly service that cleans the burner and checks those runs $150–300. A heat pump's sealed refrigerant circuit is likewise off-limits to DIY, though you can rinse its coil and keep leaves clear yourself. If a heater short-cycles or throws a fault code, resist the urge to keep resetting it and get it looked at before minor damage compounds. A repair-or-replace check helps once it is aging.
This whole checklist ships as reminders in OnOtto: every task above, on the right schedule for your home, snooze-proof.
Load this checklist as remindersFrequently asked questions
Why is my pool heater not heating the water?
Most no-heat and short-cycling problems trace to water flow or scale, not the heater's controls. A dirty filter, a clogged pump basket, or a closed valve starves the heater of flow and trips its safety switch, so it fires briefly and quits. Scale inside the exchanger does the same by choking the passages. Check and clean the filter and basket first, confirm the pump is moving water, and only then suspect the gas valve, igniter, or a failing sensor.
Gas heater or heat pump: which lasts longer?
Heat pumps generally win on lifespan. A gas heater fires hard and hot and typically lasts 5 to 10 years, while a heat pump, which moves heat rather than burning fuel, often runs 10 to 20. Gas heats the pool faster and works in any weather, so it suits short seasons and spas; a heat pump costs far less to run but needs air above roughly 50F to be efficient. The lifespan breakdown compares them in detail.
How does scale actually damage a heater?
When pH and calcium hardness run high, minerals drop out of the water and crust onto the hot copper of the heat exchanger. That layer acts like insulation, forcing the heater to work harder and burn more fuel to move the same heat, and it traps that heat in the metal until the tubes overheat and crack. Low pH does the opposite kind of harm, eating the copper away. Keeping pH between 7.2 and 7.6 is what prevents both.
Should I repair or replace an old pool heater?
If the failure is the heat exchanger and the heater is near or past its expected life, replacement usually wins, since a new exchanger can run $500 to $1,500 before labor and the rest of the unit is aging with it. Ignition parts, sensors, and valves, by contrast, are affordable fixes on an otherwise healthy heater. Weigh the repair against a full replacement of $2,000 or more with the repair-or-replace guide.