Sta-Rite · Max-E-Therm
Max-E-Therm not heating? Read the lights first.
We fix Sta-Rite Max-E-Therm heaters across Brevard County. Its POOL, SPA, SERVICE HEATER and SERVICE SYSTEM lights, plus an LED on the board, each point somewhere different.
Before anyone cycles the power, write down the plate model, the display reading and which light is lit.
Start with the nameplate
The Max-E-Therm is the SR series: 200,000, 333,000 or 400,000 BTU/hr, on natural gas (NA) or propane (LP).
What the plate tells us
| On the plate | What it designates | Why it changes the diagnosis |
|---|---|---|
| SR | The SR pool and spa heater series — the Max-E-Therm platform. | It puts the unit on the forced-draft, direct-ignition control path rather than a standing-pilot one. |
| 200 / 333 / 400 | Rated input in thousands of BTU per hour. | Input sets the gas supply and vent expectations, and it decides whether a slow-heat complaint is a fault or a sizing reality. |
| NA | Natural gas. | Fuel decides which orifice and gas-pressure figures apply. A conversion is a documented procedure, not a guess. |
| LP | Propane. | Propane supply, tank level and regulation are part of a no-fire call before any board is suspected. |
| HD | A third model column in the manual beside NA and LP — SR200HD, SR333HD, SR400HD — with no fuel letter on the plate. | Send the complete plate and the rating-label fuel. An HD model number alone does not tell us which gas train is in the cabinet. |
Send the serial number too — parts may differ across build years. If the cabinet itself says Pentair, use our Pentair repair page.
Service lights, and what each one means
The diagnostic LEDs on the back of the control board are the quickest way to see what tripped.
Board LEDs, plus the numbered codes later boards show on the display.
No match — call us with the model and what the display shows.| LED | What it is | What it means | What to record |
|---|---|---|---|
| PS | Water pressure switch | The water-side pressure switch is open, so the control will not allow the burner to run. | Record pump speed, filter condition and valve positions. Do not jumper a safety switch. |
| AFS | Air flow switch | The switch that senses pressure drop across the air metering orifice is open — combustion air is not proven. | Note whether the blower spins up at all, and for how long, before the light latches. |
| HLS | High limit switch | Opens when heat-exchanger outlet temperature climbs past 135° F (57° C). | Leave the setpoint alone and write down the water temperature the display showed. |
| AGS | Automatic gas shut-off | Opens when heat-exchanger outlet temperature climbs past 140° F (60° C) — a second-pass overtemperature. | Treat repeated AGS as a flow or heat-transfer problem, not a nuisance trip. |
| SFS | Stack flue sensor | The flue-temperature sensor has shut the heater down on excessive stack temperature. | Stop cycling power. Repeated stack faults point at combustion and the exchanger, not the sensor alone. |
| THERMISTOR | Water temperature sensor | The board flags the water-temperature sensor circuit rather than a safety switch. | Photograph the display and the LED that is lit; the circuit and the sensor test differently. |
Any LED may flash at power-up. The one that stays on after a restart is the one to report.
Numbered codes on later boards
E05open stack flue sensor;E06shorted.E01and126are the same open/short pair on the water temperature sensor.
Open and shorted can mean a harness, a sensor or a board. Send the exact characters on the display.
Got the light and the code? Call (321) 536-9122 or schedule service. Schedule Service or call (321) 536-9122.
Symptom, likely cause, next step
Blower spins, then everything stops
Combustion air is not proven (AFS), or ignition is not lighting in time. Stop restarting it and note how long the blower runs.
Pump runs, heater will not fire
Usually PS: no water-side proof. A two-speed pump on low is a known cause. Note the pump speed you normally run.
Fires, then trips on temperature
HLS at 135° F or AGS at 140° F: heat is not leaving the exchanger. Usually flow. Note how many minutes it runs first.
Stack fault, or a burnt smell at the flue
The stack flue sensor is doing its job. Leave the heater off — do not keep cycling power to clear it.
Temperature on the display wanders
The sensor circuit, thermal regulator or a bypass restriction. Check the display against a thermometer at the return and photograph both.
Runs fine, water barely warms
Scale, or exchanger damage from water chemistry. Keep any chlorinator or salt cell downstream of the heater. We service salt chlorine generators too, and check where yours is plumbed.
Sound like yours? Call (321) 536-9122 or schedule service. Schedule Service or call (321) 536-9122.
Repair it or replace it?
It depends on the part, not the age. We check it against your plate and tell you plainly whether it is worth chasing.
Points toward repair
- The fault names a switch, a sensor or an ignition part, not the exchanger.
- The part for your plate and serial can still be sourced.
- The cabinet, exchanger and gas train test sound under a full heat call.
- The problem is flow or chemistry, and the heater itself is intact.
Points toward replacement
- The heat exchanger is scaled or corroded through.
- The control board revision for that build is no longer obtainable.
- Several safety devices have failed on the same unit within one season.
- Gas supply, venting or pad conditions have to change anyway.
The order we follow on a service call
- Confirm the plate: series, input, fuel, and serial number.
- Confirm the basics — pump running, no blockages, valves set, time clock correct.
- Confirm supply voltage against the plug fitted in the control box. A 120-volt plug on a 240-volt line destroys the transformer, control board and ignition control module.
- Read the front panel: green
POOLorSPA, redSERVICE SYSTEM, redSERVICE HEATER. - Read the diagnostic LEDs on the back of the board after a restart.
- Follow the safety-switch path the lit LED names, with the safety circuit intact.
- Test the water side — flow, thermal regulator, bypass, exchanger condition — before calling it a control failure.
Replacing it? Read gas versus heat pump first.
"Went to use our spa heater and found the unit totally unresponsive. Checked all the easy stuff and couldn't figure out the problem, pool company referred me to Nat Pro. Service was scheduled within a couple of days. Tech solved the problem and patiently explained everything. I can't think of a single thing these folks could have done better…highly recommended."
Steven Newell
Tell us what the Sta-Rite is doing
Send the full model number from the plate, the display reading, and which light is lit. That tells us whether it is a switch or a sensor before we arrive.
Sta-Rite questions
Is a Max-E-Therm the same as a MasterTemp?
They share a platform and the same safety chain: pressure switch, air flow switch, high limit at 135° F, gas shut-off at 140° F, stack flue sensor. They are not the same model, so we check parts against your plate.
Can I just jumper the switch to get through the weekend?
No. The manual warns against it under a fire and explosion hazard heading. A latched heater is a repairable heater.
Does salt water damage a Sta-Rite heat exchanger?
Chemistry and scale wear an exchanger, and a heater downstream of chemical feed sees the worst of it. Keep the chlorinator or salt cell downstream of the heater.
Sources: Max-E-Therm manual, Section 4 Troubleshooting · Pentair Max-E-Therm manual · MasterTemp guide · SR owner's manual
Get the Sta-Rite diagnosis right.
Model, display reading, and the light that stayed on. With those three, we can usually tell you what's wrong before we arrive.
or text (321) 536-9122 Include photos of the fault on the display and the rating plate.Office closed? Text us now and we'll reply during office hours.