Whether it is your pool or the attached spa that has stopped heating, the cost question arrives fast and most pages answer it with a shrug and a range. So here are our actual numbers, what moves you within them, and the symptoms worth knowing before you call anyone.
| What you need | What it costs | What that covers |
|---|---|---|
| Gas heater repair | $350–$1,200 | Diagnosis and the repair itself. Where you land depends on what failed, not on how old the heater is. |
| New gas heater installation | $4,400–$5,600 | A full, professionally installed unit, including the gas and electrical connections it needs. |
Diagnosis is free. These are the ranges we actually quote in, not national averages.
A $350 repair and a $1,200 repair are both common, and the difference is almost never the brand. It is whether the failed part is a wear item on the front of the heater or something structural behind it.
| Where in the range | Typically |
|---|---|
| Lower end | Ignitors, flame sensors, pressure switches, thermostats, and wiring damage, including the kind rodents cause. |
| Middle | Control boards, gas valves, blower assemblies, and multiple smaller faults found at once. |
| Upper end, or into replacement | Anything involving the heat exchanger. That is the expensive component, and once it has scaled through or started leaking the conversation changes. |
We see the same handful of brands constantly — Pentair, especially the MasterTemp, plus Hayward, Raypak and Jandy — and nearly every failure traces back to one of three root causes regardless of which one is on your pad.
That third category is worth dwelling on, because it is where money gets wasted. A heater that short cycles is usually reporting a flow problem upstream of itself. We go through how to tell in what a heater that will not run is telling you.
A code will not tell you why something failed, but it will tell you which system to look at, and that alone can save a visit. We have written both of the brands we see most up properly, code by code:
Gas pool heaters last roughly seven to ten years. Where yours falls in that range says a lot about whether repairing still makes sense.
| Heater age | General guidance |
|---|---|
| 0–5 years | Repair almost every time. |
| 5–8 years | Still usually worth repairing, particularly if this is the first real issue you have had. |
| 8–10 years | A judgment call. Minor fixes are still reasonable, but it is a good time to start planning for replacement. |
| 10+ years | Replacement tends to be the better value. |
Past ten years you are beyond typical lifespan, and a new unit arrives with a fresh warranty. That is the whole argument.
The exception, and it is a real one: a cheap isolated fault on an older heater that is otherwise sound is still worth fixing. Age is a clue, not a verdict.
Orange County water is hard, and a pool concentrates it further, because every gallon that evaporates leaves its minerals behind. Those minerals build up as scale inside the heat exchanger, where nobody can see them, narrowing the passages and choking off heat transfer.
The heat exchanger is also the most expensive component in the unit, so this is not a cosmetic problem. It is why a heater struggling despite otherwise normal maintenance is worth mentioning to us, and why replacing a heater without talking about water balance only resets the clock.
In most residential setups a single gas heater handles both the pool and the attached spa. It is worth saying plainly because it changes how people describe the problem: a spa that will not heat is very often a pool heater fault, and a pool that will not warm affects the spa too.
It also means the valve actuators and the automation that switch between the two are part of the picture. A heater in perfect health will not warm your spa if the system never switches into spa mode.
Send a photo of the equipment pad and the display, and tell us what the heater is doing. Diagnosis is free and honest, with no pressure and no upsells.
Get a Free EstimateACE Pool Repair & Remodel is a licensed California pool contractor, CSLB #1075061, based at 251 E Imperial Hwy, Fullerton, CA 92835, serving Orange County since 2014. We have repaired and installed gas pool and spa heaters across Orange County since 2014, and we do not run after-hours emergency calls. Related reading: pool heater not working, Pentair MasterTemp error codes, Jandy JXi error codes, heat pump vs. gas heater, pool heater repair & installation.
