I always liked to sit in the back row of Mr. Johnson’s high school physics class with my classmate Tomas where we would goof off and get into random mischief, sometimes involving a Bunsen burner. When it came to test time, we would usually turn in our tests first and score 110% with the bonus questions. We were met with annoyance from our classmates, having skewed the bell curve, and skepticism from our teacher. On one test day Mr. Johnson made me sit at his desk to take the test, thoroughly convinced that Tomas and I were cheating. When I was was the first to turn in my test and scored a perfect 113% (he had a strange and generous bonus system), he asked me how I did it. I told him “this stuff is all common sense.” He was still irritated, but I think I caught a little smile.
I am often faced with the uncomfortable task of telling homeowners that while lovely, their pools have “pool coolers” built into them. They look at me quizzically and ask me what I mean. I point over to the spa spilling over into the pool, fountain, waterfall, bubblers, and other features and again tell them that their pool builder installed pool coolers for them. It’s at that a-ha moment that they realize the common sense of the situation. Like blowing on a cup of coffee or stirring a cup of soup, anything that agitates the surface of a liquid or sends liquid into the air results in heat being lost to cooler air.
The vast majority of heat lost from pool occurs at the surface through evaporation, and pool features increase evaporation!
Now this is a wake-up call for people who are currently heating their pool with an electric heat pump or gas pool heater. These traditional heaters cost huge amounts of money to operate, especially during cooler conditions when heat loss can be great. For every degree of heat loss, they are paying to heat the pool back up. It’s common sense. With solar pool heaters, while there is no cost of operation, the pool coolers are constantly working against the solar pool heating system, slowing the heating process and reducing the maximum attainable temperature levels.
Since pools usually run all day, the pool is constantly being cooled by these features, and most of the time people are not even home, or at least they are not staring at their pool all day. What I advise people to do is to heat their pool with no features on, and then turn on features when company comes over or when they want to enjoy the ambiance of their beautiful pool features.
On a good note, these features can cool a pool slightly when the pool gets like bathwater in South Florida summers, but high ambient air temperatures reduce their effectiveness and only have a small effect. Overall, pool features result in cooler pool temperatures, waste energy, and do little good other than looking and sounding nice. Consider this when building a new pool, and if you already have water features, consider turning them off if possible while heating the pool.