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    Most solar collectors are installed on the roof, as long as they are not too steep and there is not too much shade.

Solar heating systems are growing in popularity among pool owners. Thermal systems, where water is circulated through panels on the roof using the pool’s pump, especially have made inroads in the market.

Here is a brief explanation of how thermal systems work and some typical problems you may encounter.

Panel discussion

Over the years, solar panels and coils have been composed of a variety of materials, primarily copper, rubber or plastic. Today, copper has become rare because of its cost and tendency to corrode. Plastic dominates an overwhelming portion of the market.

There are a variety of plastic panel configurations. Basically, the system involves two large tubes that frame a series of smaller perpendicular ones through which the water flows.

To calculate the number of square feet of solar panels needed, many experts simply match the square footage of the surface of the pool. If the roof faces south or west, however, they may use less.

The majority of installations are done atop the roof. If it is too steep or shady, however, an independent structure must be built to accommodate the panels.

Once on the roof, the panels can be attached with a variety of hardware. Most drill through the roof’s tiles/shingles to hold the brackets in place and then inject a UV-protected silicon into every hole. The silicon helps deter leaks, and the brackets keep the panels in place. To guard against the wind, the panels are strapped down. And, adjustable header clips are attached to the tops and bottoms of the panels.

Then, the panels are plumbed into the pool’s circulation system. This step may vary, depending on the manufacturer and the distance of the pool to the house. Lastly, the system is automated via a control pad. Sensors on the rooftop panel and at the controller monitor the temperature of the water in the tubing and in the pool, so adjustments can be made accordingly.

Typical issues

While the technology used in solar heating has been around for ages, the systems themselves still can fall victim to the occasional glitch. For detailed information on your specific system, refer to the manufacturer’s manual. Following are six typical solar system problems that service techs may encounter, along with tips on how to fix them.

1. Controllers

As with most controllers, whatever can go wrong with an actuator valve can go wrong with these systems as well, experts say.

A common culprit is the pool owner, who often will leave the toggle switch in the wrong position. When this happens, the pump won’t operate even if the sensors indicate it should.

To remedy the situation, some simply glue the switch in place so it can’t be moved. If the pool needs to be shut down for maintenance, the tech can bypass the switch by going directly through the control panel.

At the control panel, you’ll find the thermostat and a switch that reads “automatic,” “on,” “off” and so forth. All you need to do is turn it to the off position when necessary; for instance, when you’re backwashing.

2. Sensors

The 10k-ohm sensors these systems use can wear out. If you suspect this is the case, attach your meter to the sensor. It should indicate that it’s getting at least 10k ohms. If it’s not, it needs to be replaced.

3. Vacuum-relief valves

Vacuum-relief valves are plumbed into the system on the roof and allow water to drain back into the pool. Because the valves open and close, over time they can wear out.

Debris also can get inside and clog them. You can easily tell that you have a problem when you notice water is coming off the roof, experts say.

Some models are engineered with the valve threaded in place. Others use a clamp to hold it.

4. Panel connections

Rubber couplings or O-rings connect the panels. They have the potential to leak if they loosen. Use a screwdriver to tighten up the stainless steel clamps that surround them.

5. Isolation valve

Make sure the isolation valve is on. Turning it off while the solar system is in automatic mode can cause severe damage to the pump in the event the system turns on. If you need to service the pool equipment, shut off the valve. But be careful to turn it back on when you’re finished.

6. Panel problems

Modern polymer panels are made to last 25 years, but eventually the tubing can split. Sometimes this may require a whole new panel. Other times the individual channels that are broken can be plugged off with a stainless steel screw, dowel or tapered rubber plug.