Pool Heater Repair

Gas heater or heat pump: they fail differently

A gas heater runs on natural gas or propane, so its repair list is about fire: the igniter, the gas valve, the flame sensor, the burners, the venting, and the safety switches that stop it from lighting when conditions are wrong. Most of its failures are electrical or combustion faults you can see or measure.

A heat pump has no flame at all. Its repair list looks more like a central air unit: the fan motor, the compressor, the refrigerant circuit, the coil, the contactor and capacitors, and the control board. It also has a water side, a heat exchanger (often titanium) that needs steady flow. Knowing which type you have tells us where to start, and which tools to bring.

When it will not fire or keeps shutting off

Every heater runs through a safety chain before it heats: enough water pressure or flow, temperature limits within range, then ignition, gas, and flame confirmation. If any link fails, the heater stops and usually shows a code or a service light.

Low water flow is one of the most frequent reasons for no heat. A dirty filter, full skimmer or pump baskets, a valve left half closed, or a variable-speed pump set too low will all keep the pressure switch from closing. It can start right after a pump upgrade, when the new pump runs at a quiet low speed that never gives the heater enough water. A heater that fires and then shuts off within minutes, over and over, is short cycling. Look first at a dirty filter, then at the high limit, the temperature sensor, and the internal bypass on models that have one. Keeping the filter clean with regular filter cleaning heads off a lot of these faults.

Soot, scale, and a corroded heat exchanger

Black soot on the cabinet or a lazy yellow flame means the heater is not burning cleanly. Low gas pressure, an undersized gas line, blocked combustion air, or insects and spiders nesting in the burner tray are common causes. Soot also coats the heat exchanger fins, which makes the problem feed on itself.

The heat exchanger is the expensive part, and water chemistry is what usually kills it. Low pH and chlorine concentrated by an inline feeder plumbed ahead of the heater eat away at the tubes. Watch for blue-green stains on the plaster, dark flecks in the pool, or water pooling inside the cabinet. Hard water causes the opposite problem: scale coats the tubes, insulates them, and makes the heater run hot and knock. Water hardness varies by supply across the area, and Sugar Land's main system has reported hardness as high as 280 ppm, so balance matters here. Our summer chemistry guide covers the numbers to keep in range.

Heat pump not heating when it turns cool

Some loss of output on a chilly day is normal. A heat pump whose fan runs but whose water never warms is not. We check airflow first: pollen, leaves, and grass clippings matted on the coil, or shrubs grown in around the unit, choke it. On cold, damp mornings the coil can frost over, and the unit may pause or run a defrost mode until it clears. A coil that frosts on a mild day, or a compressor that runs with no temperature rise, points to a refrigerant or sealed-system problem.

The electrical side matters too. Contactors and capacitors wear out, and in Texas fire ants are known to pack into outdoor electrical compartments and short them out. When a sealed-system repair on an older unit costs close to a replacement, we tell you, and pool heater installation covers the options.

How Houston owners actually use a heater

Through the hot months, Houston pools stay warm enough to swim without help. A heater earns its keep by stretching swim season into spring and fall and by heating the spa on winter evenings. That pattern means many heaters sit idle all summer, which is when ants, spiders, and rodents move in and humid air works on igniters and connections. The first cool weekend is when those problems surface.

Cold snaps are the other risk, because water left standing in a heater can freeze and crack it. If you have a spa, our spa and hot tub service keeps the heater, jets, and water in shape together, and the freeze protection guide explains how to keep water moving through the heater on the coldest nights.

Signs your heater needs a repair

• The heater clicks, tries to light, and gives up
• A pressure, flow, or service light comes on
• It fires, shuts off within minutes, and starts again
• Black soot on the cabinet or a yellow, lazy flame
• Water or rust stains inside the heater cabinet
• A heat pump fan runs, but the water does not warm
• The spa takes much longer to heat than it used to

Heater repairs we handle

• Igniters, flame sensors, and gas valves
• Pressure switches, flow switches, and high limits
• Burner tray cleaning and the causes of sooting
• Heat exchanger inspection for scale and corrosion
• Heat pump fans, contactors, capacitors, and coils
• Thermostats, sensors, control boards, and automation settings
• Pump speed and valve setup so the heater gets enough flow