Can I fix Hayward code HS myself?

Start with these safe checks: Check the pump is running and the baskets, filter and valves aren't restricting flow. If HS repeats with good flow, call a qualified tech.

When should I call a technician for code HS?

If HS repeats with good flow, call a qualified tech. Smell gas? Leave right away, don't touch light switches or phones inside, and call your gas utility or 911 from outside. Never open a gas valve, burner, gas line, vent or flue connection, or bypass a safety switch. Repeated lockouts, scorching, soot, or a CO alarm mean shut it off and call a licensed gas technician.

Hayward Pool Heater Error Code HS: Water too hot / fast…

What HS means

Return water is above 105°F, or it rose more than 6°F within 60 seconds, which is a sign of low flow.

Likely causes

Low flow through the heater
Dirty filter
Closed valves

Safe first checks

Check the pump is running and the baskets, filter and valves aren't restricting flow.

When to stop

If HS repeats with good flow, call a qualified tech.

Checked against: Hayward Universal H-Series heater troubleshooting guide (UHS16b): diagnostic codes. Codes can differ by model and year, so confirm with your owner's manual.