--- title: "Pool Heater Will Not Ignite: What to Check Before You Call" description: "Pool heater won't fire up? Check the pump, set point, breaker and freeze mode first. Learn what error codes like IF and LO mean and when to call a pro." url: https://marinapool.multisites.ai/post/pool-heater-not-igniting publisher: Marina Pool Services phone: +1-817-896-1120 quote: https://marinapool.multisites.ai/contact --- # Pool Heater Will Not Ignite: What to Check Before You Call Before you call, confirm the pump is running, the heater is on, and the set point is above the water temperature. Check the breaker and any freeze-protection mode. If the display shows a code such as IF, LO or AO, stop and call a service pro. Do not work on gas parts. RepairPublished October 21, 20264 min read ## Why won’t my pool heater ignite? Often the cause is simple. The pump may be off, the heater may be disabled, or the set point may sit below the water temperature. Other times the heater has found a fault and locked itself out. Start with the basics, then read the display. Hayward’s troubleshooting page gives a clear order of checks. This post follows it and adds general safety advice. ## What are the first checks? Work through these in order. They take a few minutes and need no tools. 1. Confirm the filter pump is on and water is flowing. A heater needs water flow to run. 2. Confirm the heater is turned on or enabled. 3. Confirm the set point is higher than the current water temperature. Hayward says to “ensure the heater is enabled and the set point is higher than the current water temperature.” 4. Check the breaker for the heater. Hayward says to inspect it and make sure it is on. 5. Look at the display for a status message or code. If the breaker trips again after you reset it once, stop and call a pro. ## What if the status says Heating but nothing happens? Hayward says a common cause is that the heater is not in “Bypass Operation” mode, shown as BO on the display. Others include a cable between the heater and the Omni controller that is unplugged or damaged, or no power to the heater. If you think any of these apply, check your manual or call a service center. ## What if the status says Ready? A “Ready” status can come from several settings. Hayward lists these: Cause What it means Set point too low The heater sees no demand for heat Heater disabled in the equipment menu It is switched off in the controller Freeze-protection mode The system blocks the heater in pool mode while freeze protection runs Water temperature sensor problem The heater cannot run without a reading On the freeze point, Hayward says the heater “cannot be operated while freeze protection is running and the system is in Pool mode,” and that you regain control once the air temperature goes above the freeze protection setpoint. Hayward also says a problem with the air temperature sensor can put the system in freeze protect mode. That matters in North Texas, where cold snaps come and go. See our [freeze protection guide](https://marinapool.multisites.ai/guides/freeze-protection). A water temperature sensor that is unplugged or damaged can also stop the heater. Hayward suggests contacting an authorized service center for sensor trouble. ## What do the error codes mean? Hayward says the heater usually shows a code when it senses a problem. The common ones are listed below. Other brands use other codes, so check your manual. Code Hayward meaning Related part IF Ignition failure [Igniter](https://marinapool.multisites.ai/glossary/igniter) and gas supply LO A pressure switch problem [Pressure switch](https://marinapool.multisites.ai/glossary/pressure-switch) AO A vacuum switch problem Vacuum switch Hayward’s advice is clear: if the heater shows an error code, or does not appear to be on after you confirm the breaker is on, contact an authorized service center. Do not try to repair it yourself. Read more about a [gas heater](https://marinapool.multisites.ai/glossary/gas-heater) and the [heat exchanger](https://marinapool.multisites.ai/glossary/heat-exchanger) in our glossary. ## What should I never do? Never open the gas train, bypass a safety switch or work on wiring. Gas and electrical work needs a qualified pro. If you smell gas, leave the area and call your gas utility or 911 from a safe distance. Do not use light switches or phones near the smell. Also do not jump or tape over a pressure switch to make a heater fire. Those switches protect the heater and your home. ## Could my pump or filter be the problem? Yes. A heater needs enough water flow. If the pump is weak, the filter is dirty or a valve is closed, the heater may not start. Check the pump basket and the filter [pressure gauge](https://marinapool.multisites.ai/glossary/pressure-gauge). Our posts on [high filter pressure](https://marinapool.multisites.ai/post/pool-filter-pressure-too-high) and [why a pump loses prime](https://marinapool.multisites.ai/post/pool-pump-loses-prime-air-leak) cover those checks. ## When is a heater worth replacing? A repair makes sense when one part has failed on a unit in good shape. Replacement can make sense when the heater is old, the heat exchanger has failed, or repairs keep coming. See our [pool heater buyer’s guide](https://marinapool.multisites.ai/guides/pool-heater-buyers-guide) and [pool equipment lifespan guide](https://marinapool.multisites.ai/guides/pool-equipment-lifespan) for ranges. A [heat pump](https://marinapool.multisites.ai/glossary/heat-pump) is another type of pool heater, with its own checks. Ask a pro which type suits your pool. ## What will a pro do? A pro will check power, flow, safety switches, the igniter and gas supply in a set order. Marina Pool Services lists pool heater troubleshooting and repair, new heater installation and equipment service for residential pool systems. Marina also services and installs Raypak, Hayward, Pentair and Jandy equipment. Marina quotes each job and offers free estimates for qualifying services. Ask about any diagnostic fee up front. See [service call](https://marinapool.multisites.ai/glossary/service-call). ## What can I tell the pro to speed things up? Have these ready when you call: - The brand and model, from the label on the heater - Any code on the display - What you already checked - Whether the pump was running - When the problem began ## Next step If your heater will not ignite, read about [pool heater repair](https://marinapool.multisites.ai/our-services/pool-heater-repair). Then call (817) 896-1120 or use the quote form at [/contact](https://marinapool.multisites.ai/contact). ## Frequently asked questions ### Why won't my pool heater ignite? The cause may be simple, such as the pump being off or the set point being too low. It may also be a fault the heater detects, such as an ignition failure or a pressure or vacuum switch problem. Check the basics first, then read the display. ### What does the IF code mean on a pool heater? On Hayward heaters, Hayward lists IF as ignition failure, LO as a pressure switch problem, and AO as a vacuum switch problem. Your model may differ, so check the manual. Hayward advises contacting an authorized service center if a code shows. ### Can freeze protection stop my heater? On Hayward Omni systems, yes. Hayward says the heater cannot run in pool mode while freeze protection is running. You regain control when the air temperature rises above the freeze setpoint. ### Is it safe to open a gas pool heater? No. Gas and electrical parts need a qualified pro. If you smell gas, leave the area and call your gas utility or 911 from a safe distance. ### How long should a pool heater last? It depends on the brand, use and water care. See our equipment lifespan guide for typical ranges. A pro can tell you if a repair or a replacement makes more sense. ## Pool terms on this page - [Freeze protection](https://marinapool.multisites.ai/glossary/freeze-protection) - [Pressure switch](https://marinapool.multisites.ai/glossary/pressure-switch) - [Diagnostic fee](https://marinapool.multisites.ai/glossary/diagnostic-fee) - [Heat exchanger](https://marinapool.multisites.ai/glossary/heat-exchanger) - [Pressure gauge](https://marinapool.multisites.ai/glossary/pressure-gauge) - [Service call](https://marinapool.multisites.ai/glossary/service-call) - [Pool heater](https://marinapool.multisites.ai/glossary/pool-heater) - [Pump basket](https://marinapool.multisites.ai/glossary/pump-basket) - [Gas heater](https://marinapool.multisites.ai/glossary/gas-heater) - [Heat pump](https://marinapool.multisites.ai/glossary/heat-pump) ## Sources 1. [Hayward: How to Troubleshoot Heater Problems](https://www.hayward.com/knowledge-base/how-to-troubleshoot-heater-problems/) Written by Marina Pool Services and checked against the sources above on October 21, 2026. City rules and product guidance change, so check the linked page before you act. Follow product labels for any pool chemical. ## Keep reading - [Freeze Protection and Winter Pool Care in TexasPool freeze protection in Texas means keeping water moving and equipment protected when air temperatures fall to freezing. A freeze guard senses the cold and starts your pump or equipment on its own. Before a hard freeze, check the freeze setting, the power supply and exposed pipes. Read your equipment manual, because settings differ by brand.](https://marinapool.multisites.ai/guides/freeze-protection) - [Pool Equipment Lifespan and Replacement ScheduleDealers and builders put pumps at about 8 to 12 years, heaters at 7 to 10, salt cells at 3 to 7 and sand at 5 to 7. Manufacturers publish warranties, not lifespans. Real life depends on run time, water balance, heat and freezes, so use these as ranges and watch for warning signs.](https://marinapool.multisites.ai/guides/pool-equipment-lifespan) - [Pool Heater Buyer's Guide: Gas vs Heat PumpA gas heater burns natural gas or propane and works in most air temperatures. A heat pump moves heat from the air into the water using electricity, and it is efficient in mild air but slows or stops in cold air. Hayward lists a 40 to 115 degree F air range for its heat pump.](https://marinapool.multisites.ai/guides/pool-heater-buyers-guide) - [Pool Filter Pressure Too High: What It MeansHigh filter pressure means water is meeting more resistance than normal. Compare the gauge to your own clean baseline. When it rises 8 to 10 psi above that number, clean or backwash the filter. If pressure stays high after cleaning, check closed valves, worn media and damaged parts.](https://marinapool.multisites.ai/post/pool-filter-pressure-too-high) - [Why Your Pool Pump Loses Prime: An Air Leak ChecklistA pool pump loses prime when air gets into the suction side. Check the water level, empty the baskets, then inspect the pump lid and O-ring. If those are fine, look at suction fittings and valves. A hidden leak in buried pipe needs a pro.](https://marinapool.multisites.ai/post/pool-pump-loses-prime-air-leak) - [Pool Equipment Repair and Replacement in GrapevinePool equipment repair starts with a diagnosis: a technician checks the pump, filter, heater, salt system, and controls, finds the cause, and recommends a fix. Marina Pool Services, a family-owned Grapevine company, repairs and installs Hayward, Pentair, Jandy, and Raypak equipment and gives free estimates for qualifying services.](https://marinapool.multisites.ai/guides/pool-equipment-repair) ## Need a hand with your pool? Call or text and tell us what your pool needs. Estimates are free for qualifying services, and same-day estimates are possible when the schedule allows. [Call (817) 896-1120](tel:+1-817-896-1120)[Get a quote](https://marinapool.multisites.ai/contact) ![A pool technician working on an equipment pad](https://marinapool.multisites.ai/_astro/technician-equipment-pad.BW5xZMNY_Zum1K5.webp)