Hayward Pool Heater HS Error Code

What HS means

High Temperature / Rapid Rise High return water temperature or rapid temperature rise detected. Heater starts, runs briefly, then shuts down. Low flow through heater (undersized pump, excessive head, bypass issues), scaled or fouled heat exchanger, variable-speed pump running too slowly during heating. Check that pump is running at adequate speed during heating cycles. Verify bypass valve isn't diverting too much flow around heater. Clean or inspect filter. If heat exchanger is heavily scaled, professional descaling may be needed.

First checks before service

This page currently documents the safe reset triage. If the code returns, use the linked source manual or a qualified technician for code-specific diagnosis.

1. 1. One-time fault event (power disturbance or transient sensor reading) common DIY

   Check: Power-cycle at the breaker/disconnect (or unplug for CPAP), restore, and run the system while watching for the code.

   Fix: If the code does not return after a full run cycle, the fault was transient — monitor, no repair needed.

2. 2. Fault persists after a clean reset occasional pro only

   Check: If the code returns immediately or every session, note the conditions (startup, heating, after rain).

   Fix: A persisting code points at the component the manual assigns to this code — that repair is technician territory.