A pool heater not working has a way of showing up on the one cool morning you were counting on it. You set the temperature, the pump is running, and the water is still cold hours later. The good news for most Ocala pool owners is that a heater that will not heat is often a flow or power problem you can sort out in a few minutes, not a dead unit. Here is how to read the symptoms, what is safe to check yourself, and when it is time to call a technician.
Around here most pools run a heat pump, with gas heaters more common where a spa needs to warm up fast. The two fail in different ways, so the first job is knowing which one is sitting on your equipment pad.
Know Which Heater You Have
A heat pump is the big square box with a fan on top, and it looks a lot like a home air-conditioning unit. It pulls warmth out of the air and moves it into the water, which is efficient in our climate but slow, so it works best when you leave it running and let it hold a temperature. A gas heater is a shorter, boxier unit connected to natural gas or a propane tank; it heats fast and does not care how cold the air is, which is why it is the usual pick for spas and quick warm-ups.
One reality check before you troubleshoot anything: a heat pump slows down as the air cools, and below roughly 50 degrees it makes very little heat. On a chilly Marion County morning, a heat pump that seems weak may be working exactly as designed. Give it warmer air and a full run cycle before you call it broken.
Pool Heater Not Working? Start With These Quick Checks
These take about ten minutes and clear up a good share of the heater calls we get, on both heat pumps and gas units.
1. Confirm the Pump and Water Flow
No heater makes heat without water moving through it. Make sure the pump is actually running, the filter is not overdue for a cleaning, and the baskets are empty. A dirty filter or a valve turned too far down starves the heater of flow, and a built-in flow switch will lock the heater out until it sees enough movement. This is the single most common reason a heater sits idle.
2. Check the Power and the Breaker
Heat pumps run on their own 240-volt circuit. Summer storms trip pool breakers all season here, so check the panel. Reset a tripped breaker once; if it trips again immediately, stop and have it looked at. Gas heaters still need 120-volt control power, so confirm theirs is on too.
3. Check the Thermostat and Mode
It sounds obvious, but confirm the setpoint is above the current water temperature and the unit is in heat mode, not "auto" or a pool-versus-spa selector pointed the wrong way. Power outages sometimes reset these back to a default.
4. Confirm the Gas Supply
On a gas heater, make sure the gas valve is open and, if you are on propane, that the tank is not empty. A surprising number of "broken" gas heaters simply ran out of fuel.
Heat Pump Symptoms and What They Mean
Runs but Makes Little or No Heat
If the fan and compressor run but the water stays cold, look at flow first, then refrigerant. A slow refrigerant leak leaves the unit running full time while barely warming the water, and a coil packed with grass clippings or love bugs cannot pull heat from the air. Clean the filter and the coil face, and if it still will not heat, it is time for a gauge check.
Ice or Frost on the Unit
A little condensation dripping from a heat pump is normal and often mistaken for a leak. Heavy ice on the coil is not; it points to low refrigerant or a defrost problem and deserves a technician.
Short Cycling or an Error Code
A heat pump that starts and stops every couple of minutes, or throws a flow or high-pressure code on its display, is protecting itself from a problem, often low water flow or a failing sensor. Note the exact code before you call; it saves diagnostic time.
Gas Heater Symptoms and What They Mean
Clicks but Will Not Light
A gas heater that tries to ignite and fails usually has an ignition, gas, or flow issue. After you have confirmed gas and water flow, the likely culprits are a corroded igniter or flame sensor, a fouled burner, or a flow or pressure switch that is no longer closing. These live inside the cabinet and are a technician's territory.
Fires Up, Then Shuts Off
A heater that lights and then quits after a minute or two is often losing the flow signal or overheating because water is moving too slowly. It can also be a venting or gas-pressure problem. Start with the filter and flow, but do not keep forcing repeated ignitions.
Soot, Rust, or a Rotten-Egg Smell
Sooting, heavy internal rust, or a persistent gas smell means shut it down and call for service. Combustion problems are not something to troubleshoot by trial and error.
Why Ocala Is Tough on Pool Heaters
Hard Well Water and Scale
Many homes across Marion County, especially the horse farms and communities outside the city on private wells, fill from the limestone Floridan aquifer, and that water runs high in calcium. When water balance drifts, that calcium bakes onto the inside of the heat exchanger, the part that actually transfers heat to your water. Scale restricts flow, cuts efficiency, and shortens the heater's life, which is why steady water chemistry is one of the best things you can do for a heater here.
Storms and Power Surges
Central Florida sees near-daily summer thunderstorms, and the surges and outages that come with them scramble control boards and trip breakers. A close lightning strike can take out a heat pump's circuit board while the rest of the unit is fine. Surge protection on the pool circuit is cheap next to a new board.
Long Shoulder Seasons
Our swim season stretches long, so heaters here run more months than they would up north, from spring evenings through fall. More run hours mean more wear, and it means a marginal part tends to fail when you are actually using the pool rather than sitting idle over a short winter.
Pool Heater Still Not Working? What Is DIY-Safe and What Is Not
Safe for any homeowner: cleaning the filter, emptying baskets, opening a valve that was turned down, resetting a tripped breaker once, confirming the gas supply, correcting the thermostat and mode, gently clearing leaves and clippings off a heat pump coil, and writing down any error code.
Call a professional for: anything involving refrigerant, gas components, igniters and flame sensors, flow and pressure switches, control boards, or opening the heat exchanger. These involve gas, high voltage, and sealed refrigerant systems that require proper tools and, for refrigerant, a licensed technician. We can connect you with a local pool company for pool equipment repair across Ocala and Marion County. Ask them to tell you plainly when a fix is not worth making.
Honest Repair Cost Ranges for the Ocala Area
Heater prices swing with the brand, the size, and whether you have a heat pump or gas unit, so treat these as planning ranges rather than quotes. National repair data in 2026 puts most pool heater repairs in the low hundreds, with a broad spread depending on the part.
Typical Heater Repair and Replacement Ranges
- Common repairs (sensors, switches, igniters)typically $250 - $800
- Major parts (heat exchanger, compressor)often $1,500 - $2,500+
- New heat pump, installedtypically $4,000 - $7,000
- New gas heater, installedtypically $3,000 - $5,000
Ranges reflect typical residential jobs; an exact price needs an on-site diagnosis.
The repair-versus-replace math is simple enough: once a heater is past eight to ten years old and the estimate climbs toward half the price of a new unit, replacement usually wins. A cracked or heavily scaled heat exchanger is the classic tipping point, since that single part can cost nearly as much as starting fresh. Rather skip the guesswork? Request a visit through our contact page and tell us what the heater is doing.
One more habit worth building: the same weekly attention that keeps your water clear also catches a scaling heat exchanger or a weak flow switch early. That is a quiet benefit of regular pool maintenance, where a technician sees your equipment often enough to notice trouble before the cold morning does.
Frequently Asked Questions About Pool Heater Problems
Why is my heat pump pool heater running but not heating?
The fan and compressor can run while the unit makes little or no heat if refrigerant is low from a slow leak, if the coil is choked with debris, or if water flow through the heater is too weak to carry heat away. Weak flow is the most common cause here: a dirty filter, a clogged basket, or a valve turned too far down. Clean the filter and baskets first, then have a technician check refrigerant and the coil.
Why won't my gas pool heater ignite?
A gas heater that clicks but never lights usually has an ignition, gas-supply, or water-flow problem. Confirm the gas valve is open and the propane tank is not empty, then check for a dirty filter or closed valve starving the heater of flow, since a flow switch blocks ignition when water movement is too low. Corroded igniters, fouled burners, and failed flow or pressure switches are common and are a technician's job.
How long does a pool heater last in Central Florida?
A heat pump usually lasts about eight to twelve years here, and a gas heater often less. Hard well water is the main reason units fall short of that: scale builds inside the heat exchanger, restricts flow, and makes the heater work harder. Balanced water, clean filters, and yearly attention to the heat exchanger help a heater reach the upper end of its life.
Should I repair or replace my pool heater?
A good rule of thumb: if the heater is past eight to ten years old and the repair estimate runs beyond about half the price of a new unit, replacement is usually the smarter spend. A cracked or badly scaled heat exchanger or a failed compressor is often the tipping point, since those parts can cost nearly as much as a new heater.