Cool mornings are back on the Georgia coast, and that means the first heater calls of the season. In our service records from the last three years, gas heater repairs climb in September and stay busy through November. Most of those calls come down to a short list of causes, and a few of them you can check yourself in five minutes.

Here is what to look at before you call, what you should leave alone, and when it is time to have a technician take a look.

Before you start: two safety rules

If you smell gas, stop. Turn the heater off, keep sparks and flames away, and call your gas utility or propane supplier from a safe distance.
Never bypass a safety switch. Pressure switches, high-limit switches and rollout switches shut the heater down for a reason. Jumping one out to "get it running" is how heat exchangers crack and fires start.

8 common reasons a pool heater won't turn on

1. The heater isn't being asked to heat

This is the most common "broken heater" we see, and it is free to fix. Check that:

The heater is switched on and set to pool (or spa) mode, not off or standby.
The set temperature is higher than the current water temperature.
Your automation system or timer is calling for heat. Many systems have a separate heater setting that can be turned off without you noticing, especially after a power outage or a software update.

2. Not enough water flow

Every pool heater has a pressure or flow switch that keeps it from firing unless enough water is moving through it. Low flow is the second most common cause of a heater that won't light. Look for:

A dirty filter (pressure gauge reading 8 to 10 psi above its clean reading).
Full skimmer or pump baskets, which fill up fast once leaves start dropping in October.
A valve turned partly closed.
A variable-speed pump running too slow. If you upgraded to a variable-speed pump, the low "filter" speed that saves you money often doesn't move enough water for the heater. The pump needs a higher speed programmed for whenever the heater runs. We fix this one constantly after pump upgrades.

3. No gas, or not enough of it

For gas heaters, confirm the gas valve at the heater is open and, if you're on propane, that the tank isn't empty or nearly so. A low propane tank can light the burner and then drop out. If other gas appliances in the house are also acting up, call your supplier.

4. Ignition problems

If the heater tries to start, clicks or fans, then shuts down and shows an ignition error, the igniter or flame sensor may be dirty or worn out. These parts are designed to be replaced, and a technician can test them quickly. Most heaters will lock out after a few failed attempts, so repeated restarts usually won't fix it.

5. Something is nesting inside

On the coast, we regularly find ants, wasps, lizards and mice inside heater cabinets. Ants in particular love the warmth of the control board and can short it out. Nests in the burner tray or exhaust can also trip a safety switch. If you remove the access panel and see debris, have it cleaned and checked before running the heater again.

6. Salt air and corrosion

Salt air from the marsh and the ocean, plus chlorine fumes when chemicals are stored near the equipment pad, corrode wiring, terminals and control boards. A heater that worked fine in April can fail in October because a corroded connection finally gave out. Storing chemicals away from the equipment is one of the cheapest ways to make a heater last longer.

7. A tripped safety or high-limit switch

High-limit switches trip when the heater overheats, usually because of low flow or scale buildup inside the heat exchanger. A tripped switch is a symptom, so the cause needs to be found, not just the switch reset.

8. Heat pump specific: it's simply too cold

If you have a heat pump, it pulls heat from the air. Most units slow down sharply once air temperatures fall into the 40s and 50s, and they may run in defrost mode on cold mornings. A heat pump that is running, fan spinning, but barely warming the water in late November may be working normally. A heat pump with no fan, no display, or an error code is a different story.

When to call a technician

Call us if:

The heater shows the same error code after you've checked power, flow and the settings.
You see scorch marks, soot, melted wiring or water leaking from inside the cabinet.
The heater lights and then shuts off repeatedly.
You smell gas at any point (call your gas supplier first).
The heater is more than 8 to 10 years old and needs a major part. At that age, it's worth comparing repair cost against a replacement before you spend money.

Our technicians diagnose gas heaters and heat pumps from all the major manufacturers, carry common parts on the truck, and will tell you plainly whether a repair makes sense or a replacement is the better buy.

Heater repair in the Golden Isles, Camden County and Amelia Island

Jeff's Pool & Spa Service repairs pool heaters across Brunswick, St. Simons Island, Sea Island, Jekyll Island, St. Marys, Kingsland and Fernandina Beach. Request a repair visit or call:

Brunswick and the Golden Isles: (912) 554-0636
St. Marys, Kingsland and Amelia Island: (912) 576-3636

Already on weekly maintenance with us? Mention the heater to your technician on the next visit and we'll schedule the diagnosis.

Frequently asked questions

Why does my pool heater turn on and then shut off?
The most common cause is low water flow, usually a dirty filter, full baskets or a variable-speed pump set too slow. Ignition problems and a weak propane supply also cause this pattern.

Why is my pool heater not heating even though it's running?
For heat pumps, cold air is the usual reason; output drops sharply in the 40s and 50s. For gas heaters, a burner that lights but doesn't stay lit, or a bypass valve set wrong, can leave the water cool.

Can I reset my pool heater myself?
You can turn it off and back on and check power, flow and settings. Don't bypass safety switches or open the gas valve train; those repairs belong with a technician.

How long should a pool heater last on the coast?
Expect roughly 7 to 10 years from a gas heater or heat pump in coastal Georgia. Salt air, chemical fumes and poor water balance shorten that.

What's the best time to get a heater serviced?
Before you need it: late summer for fall swimming, and February or early March for spring. Heater calls peak in October and April, so booking ahead gets you on the schedule faster.

Pool Heater Not Turning On? 8 Common Causes and When to Call a Tech