Pool Heater Repair
Heaters are the most complex item on the equipment pad and the one where homeowner troubleshooting should stop soonest. Gas, combustion and high-voltage electrical are all involved, and none of them are DIY territory.
Safety comes before diagnosis
This is the one repair category where the honest advice is mostly "call someone". A gas pool heater combines a gas supply, an ignition system, a heat exchanger and mains electrical in an outdoor, wet environment.
Common faults and what they cost
| Symptom | Likely cause | Typical repair |
|---|---|---|
| Will not ignite | Igniter, gas valve, flame sensor, or gas supply | $250–$800 |
| Ignites then shuts down | Flame sensor, pressure switch, or poor water flow | $200–$600 |
| Error code on display | Depends entirely on the code | $150–$900 |
| Heats very slowly | Scaled heat exchanger, undersized unit, or low gas pressure | $300–$1,200 |
| Leaking water | Heat exchanger or header — often terminal | $400–$2,500, or replace |
| No power at all | Breaker, transformer, or control board | $150–$900 |
| Corroded heat exchanger | Long-term chemistry imbalance | Usually replace the heater |
| Heat pump not heating | Refrigerant, reversing valve, or ambient temperature too low | $300–$1,500 |
What you can safely check
- Note the error code exactly. Photograph the display. The code is the single most useful piece of information you can give a technician.
- Confirm water is flowing. Most heaters refuse to fire without adequate flow. A dirty filter or a failing pump will stop a perfectly healthy heater.
- Check the filter pressure. High pressure means restricted flow, which is a very common reason a heater will not run.
- Check the gas supply is on. At the valve only. If other gas appliances also fail, the problem is upstream of the pool.
- Check the breaker. Even gas heaters need electrical power for their controls.
- Check the thermostat setting. Obvious, and it accounts for a fair number of service calls.
What not to attempt
- Do not open the combustion chamber. Gas and combustion components are for qualified technicians only.
- Do not bypass a safety switch. Pressure switches and high-limit switches exist to prevent fires and heat-exchanger failures. Bypassing one converts a fault into a hazard.
- Do not work on the gas line. Including tightening fittings. That is gas-fitter work.
- Do not descale a heat exchanger yourself. It involves circulating acid through the unit and can destroy the exchanger if done wrong.
- Do not ignore repeated shutdowns. A heater cycling on a safety switch is reporting a genuine fault, not being temperamental.
When a heater is past economic repair
Heaters typically last 10–15 years for gas units and slightly longer for heat pumps. A few signals mean the money is better spent on replacement.
- The heat exchanger is corroded or leaking — usually the most expensive single component.
- The unit is over twelve years old and needs a major part.
- The repair quote exceeds roughly half the cost of a new heater.
- It has needed repeated repairs in the last two seasons.
- Parts are no longer available for the model.
- It has always been undersized for the pool, in which case repair fixes the wrong problem.
What kills heaters early
Nearly every premature heater failure traces back to one of these, and all four are avoidable.
Water chemistry
Low pH corrodes the heat exchanger from the inside. High calcium scales it up. Both are slow, invisible, and expensive.
Poor water flow
Running with a dirty filter or a failing pump makes the heater cycle on its safety switches, wearing components.
Undersizing
A heater too small for the pool runs constantly and never satisfies, which shortens its life.
No off-season care
Rodents and insects nesting inside an idle heater cause a surprising share of spring failures.
What this project needs measured
Measurements are only requested when they change the price of the work you selected. Everything below is collected inside the estimator — you can enter dimensions you already know or measure as you go.
Required
No measurement required
This project is diagnosed from symptoms and equipment details rather than dimensions.
What the estimator will ask you
- Heater type: gas, electric heat pump, or solar
- Brand and model from the data plate
- Any error code shown on the display
- What happens when you try to start it
- Roughly how old it is
- Photos of the heater and its display
- How urgent this is
- Whether you would consider replacement
How to read a PoolSavr estimate
- Step 1
Instant estimate
Based on your project selections and general pricing assumptions. Useful for deciding whether a project is realistic.
- Step 2
Measured estimate
Uses your pool, spa, or deck dimensions to price the work against the areas actually being resurfaced, tiled, or replaced.
- Step 3
Contractor proposal
Prepared by a licensed professional after inspecting the site. This is the only number that becomes a contract.
PoolSavr is an estimating and matching platform. We do not perform pool work ourselves — licensed local professionals do. Contractors pay PoolSavr for qualified project leads, which is how the estimating tools stay free for homeowners. A PoolSavr estimate is a planning range, never a guaranteed quote — read thefull estimate disclaimer.
Frequently asked questions
- Why will my pool heater not turn on?
- The most common causes are inadequate water flow — a dirty filter or failing pump — followed by igniter or gas valve faults, and control-board failures. Check the filter pressure and confirm the pump is circulating properly before calling, since that alone resolves a fair share of cases.
- How much does pool heater repair cost?
- Most repairs run $200–$900 including the service call. Igniter and sensor faults sit at the lower end; control boards and heat exchangers at the upper. A heat exchanger replacement at $400–$2,500 usually means the heater is worth replacing instead.
- Can I fix my pool heater myself?
- Realistically, no. You can check the filter pressure, confirm water flow, note the error code and check the breaker and thermostat. Beyond that, a gas pool heater involves gas supply, combustion and mains electrical in a wet outdoor environment — that is qualified-technician work.
- How long does a pool heater last?
- Gas heaters typically last 10–15 years and heat pumps slightly longer. Water chemistry is the dominant factor — low pH corrodes the heat exchanger and high calcium scales it, and both quietly halve a heater’s life.
- Should I repair or replace my pool heater?
- Replace if the heat exchanger has failed, the unit is over twelve years old and needs a major part, the repair exceeds half the replacement cost, or it has needed repeated repairs recently. Repair anything younger with a discrete component fault.
Ready to see what your project costs?
Start with the work you are considering. You will get a preliminary range before anyone asks for your phone number, and you decide whether to request a contractor review at the end.