Winterizing / reviewed Sep. 2026
How to Winterize an Above-Ground Pool Heater Safely
Close a heat pump, gas heater, electric heater, or solar collector system using a model-specific, no-shortcuts winterizing plan.
Shut down the heater by its manufacturer’s sequence, isolate power or fuel as directed, and remove water from every specified component before freezing conditions. Cap or store parts only as the manual permits. Because designs differ, there is no universal drain-plug list; the model manual is the primary checklist.
Identify the equipment before closing day
Record the full model number for the heater, pump, filter, salt system, and solar controls, then download their manuals while labels remain readable. Trace the normal flow path and photograph valves. Above-ground packages are frequently modified over time, so instructions for the pool alone may not describe an added heater or bypass.
Let chemistry and cleaning happen in the right order
Balance and sanitize the pool according to the pool-care plan before final shutdown, giving each labeled treatment its required circulation time. Clean the filter through its own approved process so debris is not stored against media all winter. Do not send a concentrated closing chemical directly through the heater or mix chemicals in a container.
Use the heater’s normal shutdown sequence
Some combustion heaters require a cool-down circulation period, while other units specify controller steps before power isolation. Follow those directions in order. Turn off fuel and electrical supplies only at the approved controls or disconnects. If you cannot positively identify a shutoff, bring in the appropriate gas, electrical, or pool professional.
Drain rather than assume gravity found every pocket
Remove only the drain plugs, unions, panels, or fittings designated for owner winterization. Flexible hoses may need disconnection and storage; heat exchangers and solar arrays may have specific purge requirements. Never use excessive compressed-air pressure, which can damage equipment and turn plugs into projectiles. Leave prescribed drains open or loosely stored as the manual directs.
Protect equipment without sealing in moisture
A tightly wrapped tarp can trap condensation, block a required vent, or invite pests to nest against wiring. Use a fitted accessory only if approved for the unit, and preserve ventilation specified by the manufacturer. Store removable controllers, plugs, and hoses in a labeled dry container so the spring opening does not begin with missing parts.
Reopen as a separate commissioning task
Spring startup reverses more than the drain sequence. Inspect for frost movement, reconnect bonding and plumbing only as specified, prime circulation, check for leaks, restore safe water chemistry, and then commission the heater. Do not energize a dry heater. If winter damage is visible or a protective device trips, stop before water reaches live components.
Questions people ask
Do all above-ground pool heaters have drain plugs?
No. Drain locations and owner-accessible parts vary by design. Use the exact model manual instead of assuming a plug location from another heater.
Can I leave a pool heat pump outside all winter?
Many are designed for outdoor installation, but they still need the manufacturer’s winterizing procedure. Climate, drainage, protective accessories, and storage instructions vary.
Should winterizing plugs be reinstalled after draining?
Follow the manual. Some instructions call for loose storage or open drains, while others specify reinstallation; the correct choice is model-dependent.
When should I hire a professional to close the heater?
Use professional service when fuel, internal electrical work, roof collectors, compressed-air purging, inaccessible drains, or unclear modifications are involved.