Should you repair or replace your pool heater?
Updated August 2026
← Every repair-or-replace call
Replace a gas pool heater once the heat exchanger corrodes or the quote passes half of a $2,000–4,500 new unit; under about 6 years, fix the igniter, pressure switch, gas valve, or control board for $150–800. Service life sets the boundary. Gas heaters typically last 5–10 years and heat-pump heaters 10–15, with a heat-pump replacement at $3,000–6,000. What retires most gas heaters is not the electronics, it is the copper heat exchanger dissolving after years of low pH or high chlorine, and that single part can cost more than half a new heater.
The short version
Sort the fault into electronics or exchanger, because the two lead to opposite answers. Controls are ordinary service items: an igniter at $150–300, a pressure switch at $100–250, a high-limit sensor at $100–250, a gas valve at $300–600, a board at $400–800. On a heater under 6 years, fix them and expect several more seasons. The exchanger decides everything else. Once the copper is scaled or eaten through and water weeps into the burner tray, you face $700–1,500 in parts and labor on equipment that costs $2,000–4,500 to replace, and the 50% rule says stop. The practical line lands near year 8 for a gas heater, though chemistry, not the calendar, is what usually gets it there.
Your situation, decided
| Situation | Verdict | Why |
|---|---|---|
| Heater will not fire, igniter or flame sensor faulty | Repair | A $150–300 part; the burner and exchanger are untouched |
| Locking out on a pressure switch fault | Repair | Often low flow from a dirty filter; verify that before buying parts |
| Gas valve or control board failed, heater under 6 years | Repair | A $300–800 part on a heater with seasons of life left |
| Water dripping into the burner tray | Replace | A corroded exchanger; the fix nears half a new heater |
| Past 8 years, scaled exchanger and repeated lockouts | Replace | The end of a 5–10 year gas heater service life |
| Heat-pump heater at 6–10 years, bad fan motor or capacitor | Repair | A $150–500 part on equipment rated for 10–15 years |
What each path costs
Repairs typically run $150–800; a replacement is $2,000–4,500 gas, $3,000–6,000 heat pump installed. Gas pool heaters last 5–10 years and heat-pump heaters 10–15. Repair through year 6, treat year 8 as the tipping point, and let a corroded exchanger end it at any age. Price your own number on the home maintenance cost calculator before you commit either way.
The repair-or-replace call is easy when you know the unit's age and service history. OnOtto keeps both, plus the maintenance that delays this decision for years.
Start your home's service log, freeFrequently asked questions
Can a corroded heat exchanger be replaced on its own?
Physically yes, financially seldom. A replacement copper exchanger plus the labor to open the heater runs $700–1,500, against $2,000–4,500 for a whole new gas heater carrying a fresh warranty. Under 4 years, especially with warranty coverage, the repair is worth pursuing. Past 6 years the corrosion that killed the exchanger has usually worked on the headers, bypass, and hardware too, so you rebuild an old heater one expensive piece at a time. Our heater lifespan guide shows where yours sits.
What ruins a pool heat exchanger so quickly?
Water chemistry, almost always. Water below roughly 7.2 pH turns aggressive and dissolves copper, while high calcium hardness scales the tubes so they overheat instead. Chlorine dosed directly in front of the pump gets pulled through the heater at full strength and eats it from inside. Low flow from a clogged filter is the fourth cause, since it lets the tubes run too hot. Weekly testing and the tasks in the heater checklist are what carry a gas heater to year 10.
Gas heater or heat pump when it is time to replace?
Pick by how you swim. Gas costs $2,000–4,500 installed, heats fast, and works in any weather, which suits weekend and shoulder-season use. A heat-pump heater costs $3,000–6,000, warms slowly, and needs air above roughly 50 degrees, but it runs for far less per hour and lasts 10–15 years rather than 5–10. Daily swimmers in warm climates usually come out ahead with the heat pump. Read how each type works before you sign anything.
My heater shuts off after a few minutes. Is that expensive?
Usually not. Short cycling on a pool heater is most often a flow problem: a dirty filter, a clogged pump basket, or a partly closed valve trips the pressure switch as soon as the burner warms up. Clean the filter and clear the baskets first and the fault often disappears for free. If flow checks out, suspect a $100–250 pressure switch or high-limit sensor. A failing pool pump that no longer moves enough water produces the same symptom, so rule it out before condemning the heater.