HP Error
Hayward Pool Heat Pump
Severity: ModerateWhat Does This Error Mean?
The Hayward HP error indicates a fault in the heat pump system. Common causes include low refrigerant, a dirty evaporator coil, insufficient airflow around the unit, or a refrigerant pressure switch trip. Most HP errors require checking airflow and the coil before calling a technician.
Affected Models
- Hayward HeatPro Heat Pump
- Hayward HeatPro HP50HA
- Hayward HeatPro HP21404T
- Hayward HeatPro HP31404T
Common Causes
- Dirty or blocked evaporator coil reducing heat exchange efficiency
- Insufficient airflow — unit installed too close to a wall, fence, or shrubs
- Ambient air temperature too cold — most heat pumps stop working below 45-50°F
- Low refrigerant charge due to a slow leak
- Refrigerant high-pressure or low-pressure switch tripped
- Failed reversing valve (heat pump stuck in cooling mode)
How to Fix It
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Check the ambient air temperature.
Hayward heat pumps require an ambient temperature above approximately 45-50°F (7-10°C) to operate efficiently. Below this, the unit will fault or fail to produce heat. If the outside temperature is marginal, wait for a warmer day before troubleshooting further.
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Inspect the evaporator coil for dirt and debris.
The large finned coil on the side of the unit acts like a car radiator — it pulls heat from the air. Leaves, grass clippings, and cottonwood debris block airflow and trigger HP faults. Turn the unit off and gently rinse the coil from the inside out with a garden hose. Do not use a pressure washer — it bends the fins.
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Verify adequate clearance around the unit.
Hayward specifies a minimum of 24 inches clearance on all sides and unrestricted airflow above the fan. A fence, hedge, or wall too close to the unit causes the unit to recirculate cold exhaust air, triggering the HP fault.
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Reset the unit and observe if the fault returns.
Turn the heat pump off at the panel, wait 5 minutes, and restart. If the HP error clears and the unit runs normally, the fault was likely a temporary pressure trip. Monitor over the next few cycles.
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Call a technician if the fault returns after clearing.
Recurring HP errors that do not resolve with cleaning and airflow checks indicate a refrigerant issue — either low charge from a leak, or a failing pressure switch or reversing valve. Refrigerant work requires an EPA-certified HVAC technician.
Frequently Asked Questions
Can I fix the Hayward HP error myself?
Cleaning the evaporator coil and checking clearance are safe DIY steps. Anything involving the refrigerant circuit — checking pressures, adding refrigerant, replacing the reversing valve — requires an EPA-certified technician. Attempting to service refrigerant lines without certification is illegal in most countries.
Why does my Hayward heat pump only show HP error in the morning?
HP errors that appear in the morning and clear by midday are classic signs of ambient temperature being too low overnight. Heat pumps struggle when air temperature drops below 50°F — the unit tries to start, cannot extract enough heat from the cold air, and faults. Once the morning air warms up, it runs normally. Consider extending your swim season heating window to daytime-only operation.