Leaving Your Solar Pool Heater for Summer: What To Do

It’s May, and that means our beloved snowbirds are heading north for the summer, leaving behind their solar pool heating systems at their Southwest Florida homes. Whether you stay here year-round or follow the flock to a milder climate, it is important to understand what to do when leaving your solar pool heater for the summer.

Typical Solar Pool Heating Bypass and Isolation Valves
A typical solar pool heater bypass valve manifold

While every system is different, our standard recommendation is to isolate your solar pool heater and not allow any water to flow through it. The main reasons you should isolate your system are:

  • Avoid issues if a leak were to develop during your absence. Physical damage from storms, animals, or other causes may result in leaks that are hard on your roof and gutters, and may allow your pool level to drop to levels harmful to the pump.
  • Eliminate stagnating water that may overheat and cause plumbing to swell, warp, or crack. This is especially problematic with black pipe and with systems that do not fully drain naturally.
  • Reduce water use. Warmer pools evaporate quicker (although for much of the summer the rain will make up any water losses).
  • Reduce chemical use. Warmer pools go through more chemicals.
  • Reduce general wear and tear on the system.

So how do you isolate your solar pool heater? It should have valves installed that allow positive isolation so no water can be pumped up to them, but not all competitors install these valves. Every one of our systems includes high quality valves that remain easy to operate for the life of your system. The steps to isolate your system are as follows:

  1. Turn off your pool pump.
  2. Wait for the system to fully drain back to the pool if plumbed to drain naturally. Most of the systems we install drain naturally. You should wait a couple of hours or until the morning to be extra cautious. If in doubt whether your system drains naturally, ask us! If your system could not be installed to drain by gravity, you will need to open a manual drain (if installed) or remove an end cap at the lowest point in the system on the roof. You may want your solar professional to provide this service for safety reasons.
  3. If you have a solar controller, turn it off by doing one or more of the following:
    • Disable solar heating
    • Turn the desired temperature all the way down
    • Put controller in vacation mode (i.e. with the SolarTouch controller, hold down the Enter button)
    • Once the valve is in the “solar off” position, for some added peace of mind, turn the small toggle switch on the back or bottom to the middle position to make sure the valve does not turn in response to the controller’s commands. This is for advanced pool owners only.
  4. If you do not have a solar controller, turn your manual solar bypass valve (3-way valve) to the “solar off” position to divert all water back to the pool at all times.
  5. Isolate your system by closing the valve on the solar feed line going up to the roof.
  6. If your system does not drain naturally by gravity:
    • Open your manual drain valve if you have one and drain out all of the water, then close it again.
    • Open an end cap at the lowest part of the system and drain out all of the water. This requires getting on the roof and is best left to a solar professional.
  7. Turn your pump back on to the regular schedule.

That’s it. If you understand how your pool plumbing works it’s not too hard to make sure you solar pool heater is ready for summer and to extend the life of the system and avoid issues in your absence. If you need a refresher, or would just prefer to let us handle it, we can come to your home for a small charge to “summerize” your system or get it ready for swimming season again.

If you are here year-round, but turn your solar pool heater off because your pool gets too warm, it is a good idea to follow the same procedures to turn off and isolate your solar pool heater. There is no reason to subject your system to extra wear and tear, and stagnating water in the solar pool heating system can cause issues in some cases.

How to Identify Valves in Your Solar Pool Heater Bypass Manifold


If you need help determining if your valve is on or off, take a look at this video below to better understand which valve position blocks the pipe:

You may ask why it is necessary to close, or even have, the isolation valve on the feed line. The reason is that the solar bypass 3-way valve has a small hole in it that allows the solar panels to drain when the pump is off. It does not provide a 100% seal against water going up to the panels. For that reason we add an isolation valve on the feed line to provide a reliable way to close off the system for service and long periods of inactivity.

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