Dip your hand near the return jet while your solar pool heater runs, and you may notice a stream of warm water entering the pool. Naturally, hotter water feels like a good sign. It seems to prove the solar panels are working hard and the pool should warm quickly. But that warm stream can fool you. In many cases, water that is not as ‘warm’ at the return jet may deliver more heat to the pool over the course of the day. How can that be?
Water Flow Matters
Solar pool heating sounds simple. Pool water travels to the roof, passes through solar collectors, absorbs heat from the sun, and returns to the pool. What often surprises homeowners is the relationship between water temperature and water flow. A swimming pool contains thousands of gallons. Heating it requires more than a small amount of very hot water. The system needs to move a large volume of warmed water for several hours.
When water moves slowly through the collectors, it spends more time on the roof. Each gallon absorbs more heat, so the water returning to the pool feels quite warm. That seems like ideal performance. The problem? Only a small amount of water may move through the system.
Picture a garden hose running at a trickle. Leave it in the sun, and the water inside becomes hot. Turn on the faucet, and the first few seconds feel surprisingly warm, but that small trickle would take a long time to heat an entire swimming pool.
Now imagine a much stronger flow. The water may not feel as hot because it moves through the panels faster. Still, far more warmed water reaches the pool every minute. That difference matters.
Faster Isn’t Always Better
More flow often improves solar heat transfer, but simply running the pump at full speed doesn’t guarantee better results. Extremely high flow creates excess pressure, unnecessary noise, and higher electricity use. It may also place more strain on plumbing connections and aging equipment.
The goal isn’t the highest possible pump speed. The goal is to find the right flow for the system. That flow depends on several details:
- The number and size of the solar collectors
- The height of the roof
- The distance between the pool and the panels
- The pipe diameter
- The condition of the filter
- The type of pool pump being used (variable speed pumps save energy)
There’s no universal speed that works for every pool. All of these factors contribute to the correct flow for your specific pool and system. A professional solar pool system installer can help you determine the correct speed for optimal performance.
Keep the Heat Once You Gain It
Even a well-designed solar pool heater struggles if the pool loses too much heat overnight. Evaporation causes a large share of that loss. Windy conditions make it even worse. A warm pool left uncovered on a cool night can lose much of the heat collected during the day.
The solution is to utilize a pool cover that helps hold that warmth in the water. It also reduces evaporation and gives the solar system less work to do the next morning. Solar collectors gather the heat. A cover helps keep it in the pool.
Helping You Get the Flow Right
The most common mistake solar pool system owners make is judging the whole system by the temperature of the return water. A solar pool heating system with steady water flow and properly balanced collectors is key to a water temperature your family will enjoy.
Solaron installs dependable solar pool heating systems throughout California. With proper system sizing, balanced plumbing, and carefully adjusted water flow, Solaron can help you get more useful heat from the sun and enjoy a longer, more comfortable swimming season. Contact Solaron to discuss a new solar pool system or improve the performance of an existing one.