Short answer
On the Hayward/Summit heat-pump models listed in the linked guide, HI indicates an open high-pressure switch. Check the exact model plate, filter-pump operation, and whether the filter and bypass allow water flow. Stop if HI returns after these visible checks. A qualified servicer must assess the pressure switch or sealed refrigerant system; do not bypass a safety switch.
Checks for Hayward HI
- Match the model plate to the models covered by the Hayward/Summit guide.
- Confirm the filter pump is running and record the filter condition.
- Record the bypass-valve position and whether water flows through the heat exchanger.
Proof to capture before ordering parts
- Photo of the complete display and when the code appeared
- Model and serial plate, including controller revision if visible
- Filter, pump, bypass position, and pad context
Stop rule
Stop if HI repeats. Pressure-switch and refrigerant-system diagnosis requires qualified service; never bypass a safety switch.
Not a diagnosis. Confirm the exact model and current manufacturer procedure before repair or parts ordering. Do not bypass safeties.
Common questions
What does Hayward HI mean on a guide-listed heat pump?
HI indicates the high-pressure switch is open on the models covered by the linked Hayward/Summit guide.
What should I check first for HI?
Match the model plate to the models covered by the Hayward/Summit guide. Confirm the filter pump is running and record the filter condition. Record the bypass-valve position and whether water flows through the heat exchanger.
When should I stop checking HI?
Stop if HI repeats. Pressure-switch and refrigerant-system diagnosis requires qualified service; never bypass a safety switch.
Related codes
Manufacturer source
Hayward/Summit Heat Pump Troubleshooting Guide (PDF). Last reviewed: . Consult the guide's model list before using these checks.
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