Winterizing a pool heater means protecting every part that holds water, not simply turning the thermostat off. Water left in an exchanger or low plumbing point can freeze and cause damage. The correct draining procedure depends on the exact heater and installation.
Use this guide to organize the shutdown and check the work. Use the manufacturer’s manual for the actual drain points, isolation method and service requirements. If those details are unclear, arrange a qualified pool equipment service before freezing weather.
Find the instructions that match your heater
Record the model and serial number from the accessible label. Confirm whether you have a gas heater, heat pump or electric resistance heater. Save the matching winterization section before disconnecting anything.
Two heaters with similar cabinets may use different exchanger layouts. One may require a drain plug; another may rely on opening specified unions. Hayward explicitly notes that drain plug requirements vary among heat pumps.
Do not copy a neighbor’s valve arrangement. Ask the installer to identify your heater’s isolation points and any plumbing that can refill it. This is especially important when equipment sits below the pool water level.
Decide between continued operation and seasonal shutdown
A working freeze protection setting is not the same as a winterized system. It may rely on power, a working pump and correctly configured controls. An outage or blocked circulation can defeat that plan.
If the pool will remain open, ask the installer whether the entire system can operate safely in your expected weather. Include the heater’s air and water temperature restrictions. See heat pump operation in cold weather for the distinction between heating capacity and freeze protection.
If the pool is closing, complete winterization before water can freeze inside the equipment. Do not wait for a generic calendar date. Local forecasts, site exposure and the equipment instructions should guide timing.
Plan the water path before opening connections
Draw a simple record of the pool, heater and nearby valves. Identify where drained water will go and whether it could reach electrical equipment. Have the installer clarify any connection you cannot positively identify.
| Item to confirm | Why it matters |
|---|---|
| Heater isolation arrangement | Pool water must not keep refilling a drained exchanger |
| All required drain points | An open union may leave water in another compartment |
| Low sections of connecting pipe | Water can remain outside the heater cabinet |
| Permitted water removal method | Uncontrolled pressure can damage equipment |
| Final winter position of openings | The procedure must prevent refilling while meeting the manual’s storage requirements |
These are planning checks, not instructions to turn unknown valves. Never loosen a union or drain fitting while the system is running or pressurized. Follow the prescribed shutdown and pressure relief procedure first.
Shut down heating and isolate energy correctly
Stop heating through the normal control and follow any required cooldown sequence. Have electrical and fuel isolation completed as specified for the appliance. A dark display is not proof that internal electrical components are safe to touch.
Gas appliances need their own manufacturer shutdown procedure. Do not use heat pump instructions for gas valves, burners or venting. Work requiring cabinet access, fuel handling or electrical servicing belongs with a qualified person.
Prevent automatic controls from restarting equipment that has been drained. Label the shutdown clearly for anyone who maintains the pool. Keep the label with the controls and in your maintenance record.
Remove water using the prescribed method
Follow the exact sequence for opening the specified unions, drains and other water containing parts. Allow water to leave completely through the intended route. Confirm the installation cannot feed water back into the heater.
The May 2025 Raypak Crosswind manual describes opening inlet and outlet connections for seasonal drainage. Other models may have additional or different requirements. That example explains why identifying the unit matters; it is not a universal draining sequence.
Some manufacturers permit a vacuum or controlled air method to remove residual water. Use only the equipment, connection and pressure limits specified for your model. Do not apply an arbitrary compressor setting from a general pool closing guide.
Do not tilt or lift a permanently installed heater to empty it unless its instructions expressly permit that action. Attached plumbing, wiring and the unit’s weight can make this unsafe. A portable model’s storage directions do not apply to every installation.
A gas heater can have more than one water containing section to empty. Pentair’s MasterTemp guide addresses both the heat exchanger and plastic inlet/outlet manifold, with additional service steps. An installer must follow that complete procedure rather than assume one visible drain empties everything.
What about antifreeze?
Do not pour antifreeze into a heater as a substitute for draining. Whether any product is permitted depends on the appliance and winterization procedure. Automotive antifreeze is not an appropriate improvised pool equipment treatment.
If a professional procedure calls for a winterizing product elsewhere in the pool plumbing, confirm whether the heater must be excluded. Keep the exact product and application instructions with the service record. Do not assume an instruction for a pipe applies to an exchanger.
Finish the winter setup deliberately
Keep removed parts labeled by their original location. Record which seals or fittings require replacement before reopening. A photograph of the completed arrangement can prevent confusion months later.
Protect openings and the cabinet only as the manufacturer directs. A suitable winter cover can limit weather and debris exposure, but it does not replace drainage. Never run the heater while covered or with required air passages obstructed.
Inspect the exterior after major storms and periodically through the closed season. Check for displaced covers, obvious refilling, debris and animal activity from outside. Do not energize the heater for a quick test while it remains winterized.
Reopen through a commissioning sequence
Before restart, have drain parts, unions and seals restored correctly. Remove the winter cover and any temporary protection that must come out. Confirm valves and controls are returned to the correct operating arrangement.
Establish the specified water circulation and inspect for leaks before enabling heat. Complete the manufacturer’s startup checks, including any professional inspection required for gas or electrical equipment. Do not run a dry heater to test the display or burner.
If freeze damage is suspected, stop and arrange inspection. Water beneath a newly reopened heater deserves investigation using the condensation and leak guide. A leak that appears only under circulation still requires attention.
Keep a closing record you can use next spring
Record the date, model, manual revision, drain points completed and the person who performed the work. Note any unresolved defect and which components remain disconnected. Keep this with your pool maintenance log.
A clear record should let the next person understand the winter state without guessing. It should also identify the checks required before heating resumes. That is more useful than a single note saying the heater was turned off.
