Hayward HDXFHLI400 High Limits | For HC-Series HDF400 | HDXFHLI001

OEM Hayward HDXFHLI400 High Limits, replacing former model HDXFHLI001, are critical thermal safety devices for Universal HC Series HDF400 pool heaters. These switches play an essential role in regulating the heater's safety by detecting excessive water temperature and instantly shutting off the unit to avoid potential damage. Manufactured with precision and durability in mind, they help protect key components from heat-related stress while supporting consistent heater operation. As a required safety feature, these OEM high limits are fundamental to the long-term efficiency and safe use of your pool heating system.

Highlights

• Specifically Designed for HC HDF400 Heaters: OEM replacement switches ensure accurate temperature monitoring and thermal control

• Automatic Protection Mechanism: Detects unsafe water temperatures and shuts down heater to avoid overheating and equipment failure

• Prevents Costly Heater Damage: Acts as a thermal safeguard to protect sensitive internal parts from high-heat exposure

• Engineered for Reliability: Built using heat-resistant materials and calibrated for consistent, accurate high-limit response

• Ensures Safe Pool Heating Operation: Helps maintain safe operation by enforcing temperature thresholds throughout heater cycles

Compatibility

• Compatible with  Universal HC Series HDF400 Heaters

Error Codes

Potential error codes that may require you to replace your High Limits are:

HS - High temperature sensing error

• A) Inlet water temperature sensor is reporting a temperature in excess of 104°F. Normal operation resumes 2 minutes after inlet water temperature sensor reports temperatures of 104°F or less. This error functions for both normal and remote thermostat modes. or

• B) Inlet water temperature sensor is reporting a temperature change at a rate faster than 6°F in 60 seconds or less while the heater is firing, indicating a potentially damaging low water flow condition. Normal operation resumes when temperatures stabilize. If this condition is detected 3 times in a one hour period, the heater will lockout.

Additional Info

Diagnosing Overheating Issues

heater keeps reaching max temp high limit tripping

troubleshoot heater lockout on hc-series hdf400

error code on screen related to temperature sensor

how to fix hdf400 heater that shuts off too soon

heater runs hot then stops hdxfhli400 needed

Component Specs and Local Pricing

check local price on hayward high limit switch kit

difference between hdxfhli001 and hdxfhli400

heat sensor part for hdf400 high temp shutoff

buying heater high limit locally for fast repair

high temp cut-off sensor replacement for hayward

Compatibility Confirmation

is hdxfhli400 compatible with all hdf400 units

which hc-series models use this safety switch

part number for high limit switch hayward hdf400

local store with hayward heater temp safety switch

confirm fitment of hdxfhli001 before local purchase

Diagram