Hurlcon Gas Heater F1 Error – Causes & Fix Guide
The Hurlcon F1 error indicates a temperature safety shutdown, usually triggered when the heater detects water above 45°C or a fault with the temperature sensor system.
This is a common fault across Hurlcon gas heaters and equivalent AstralPool HX and JX models. In most cases, the issue is not actual overheating, but a faulty thermostat sensor lead or related component.
Note: These Hurlcon heater error codes and faults also apply to AstralPool HX and JX gas heaters, as they are the same heater models rebranded under AstralPool.
This guide explains what the F1 error means, what causes it, and how to fix it.
What Causes a Hurlcon F1 Error?
- Water temperature exceeding 45°C (rare)
- Faulty thermostat sensor lead
- Corroded brass sensor pocket
- Damaged or melted sensor wiring
- Poor water chemistry causing corrosion
Many F1 errors are linked to temperature sensor faults rather than actual overheating.
Which Heaters Does This Apply To?
This F1 error applies to the following Hurlcon and AstralPool gas heater models:
- WX75, WX120
- HX70, HX120 (also AstralPool HX)
- JX130, JX160 (also AstralPool JX)
- MX125, MX150, MX200, MX250, MX300, MX400, MX500
- Natural Gas and LPG models
What is the Hurlcon F1 Error?
The F1 error is a safety shutdown triggered when the heater detects water temperature above 45°C.
However, in most cases, the water temperature is normal and the error is caused by a faulty thermostat sensor system.
Before proceeding, always:
- Check actual water temperature with a thermometer
- Confirm the pool or spa is not overheating
If the water is not hot and the error remains, the fault is likely with the sensor system.
Common Causes of F1 Sensor Faults
The F1 error is generated by the thermostat sensor lead connected between the control board and the water manifold.
Common failures include:
- Corrosion inside the brass sensor pocket
- Water ingress damaging the sensor tip
- Cut, melted, or damaged wiring
- Poor water chemistry accelerating corrosion
These issues are commonly associated with water flow problems or long-term system wear.
Where is the Thermostat Sensor Located?
The thermostat sensor is located in the brass pocket on the inlet water manifold.
- HX models: top rear panel access
- JX models: lower side panel access
- MX models: top panel above manifold
If corrosion or damage is visible, the sensor and possibly the brass pocket must be replaced.
How to Fix a Hurlcon F1 Error
Follow these steps to diagnose and repair the issue:
- Turn off power to the heater
- Reset the system by unplugging for 10 seconds
- Restart the heater and observe operation
- If error persists, inspect thermostat sensor and wiring
- Check brass sensor pocket for corrosion or damage
- Replace sensor lead if damaged
- Replace brass pocket if corroded
Important: Do not attempt to cut and rejoin the sensor wire — this will fail due to heat exposure.
Replacement Parts Required
Most F1 repairs require replacing the thermostat sensor lead and brass sensor pocket:
In some cases, additional components may be required:
When to Call a Technician
If the heater continues to display the F1 error after replacing components, professional diagnosis is recommended.
Gas heater faults involving sensors, control boards, or overheating should be assessed by a licensed technician.
Related Hurlcon Heater Troubleshooting
For broader troubleshooting across all gas heater brands, see our Gas Pool & Spa Heater Troubleshooting Guide .
This article is for general information only. HeaterFix recommends all gas heater repairs be carried out by a licensed gas fitter.
