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

OEM Hayward High Limits HDXFHLI400, formerly known as HDXFHLI001, are essential safety components engineered for use with Universal HC Series HDF400 heaters. These high limit switches are responsible for monitoring the heater's water temperature and automatically shutting off operation if temperatures exceed safe thresholds. This critical function helps prevent overheating, protects internal components, and promotes long-term heater reliability. Built with durable materials and precise calibration, the HDXFHLI400 high limits ensure your pool heating system runs efficiently and safely under varying operating conditions.

Highlights

• OEM Safety Switches for HDF400 Heaters: Designed to meet Hayward's exact specifications for maintaining thermal safety in high-capacity heaters

• Automatic Shut-Off at High Temperatures: Triggers shutdown if water exceeds safe operating range, helping to prevent critical overheating damage

• Safeguards Heater Components: Provides thermal protection that reduces stress on heater internals and extends service life

• Durable, Precision-Engineered Parts: Built to withstand repeated exposure to heat and system cycling without losing accuracy

• Supports Reliable Heating Operation: Ensures your heater continues to function within safe temperature limits for consistent, efficient pool heating

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

Signs Your High Limit Switch Failed

hdf400 heater keeps shutting off check high limit

hayward hc-series overheating during startup

water too hot heater won’t reset high limit issue

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Part Specs and In-Store Replacement

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Model Fitment and Identification

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Diagram