How automatic is a solar pool heater?
Completely. All you do is set your pool pump’s time clock or automation system to run during the daylight hours, then set the solar pool heater’s automatic control temperature indicator to your preferred temperature. The control system takes care of the rest. Sensors compare the temperature at the solar collectors with you pool water temperature. Whenever the solar collector temperature is at least four degrees warmer than your pool water, the control system adjusts a motorized valve to divert pool water through the solar collector panels if your pool is not at the desired temperature.
And even if your pool cannot reach your preferred temperature setting during the coldest winter weather, your pool will always be warmer than a neighbor’s similarly situated unheated pool, without you spending a penny on expensive fuel.
How can I determine what size and type of pool heater is best for me?
Every situation is different and relying upon simple “rules-of-thumb” can lead to unrealistic expectations and unhappy cusotmers. Among the many factors we consider when sizing a pool heater are:
desired swim season length
preferred water temperature
type of pool use (exercise, kids playing, casual dips, etc.)
screen enclosures and other direct shading of pool surface
open space and windbreaks, especially along northwest to northeast exposures
distance between pool equipment pad and pool heater
for solar, availability of sufficient unshaded roof or other installation location
for solar, direction best available roof area faces
willingness to use a pool blanket
ability and willingness to pay increasing energy costs
I keep reading about the pool’s surface area. Why don’t you use the number of gallons in my pool for sizing?
Your pool’s water volume (gallons) does matter, especially if your system is installed during the winter, because the water temperature of an unheated pool during the winter months can be as much as 20 degrees below the desired temperature. In this case, dividing the estimated average daily Btus of heat input from the heating system by the pounds of water in the pool (water weighs 7.5 pounds per gallon) tells us how fast we can bring the pool up to the desired temperature.
On the other hand, in normal operation we are simply trying to replace the two to four degrees of water temperature lost overnight, and most heat loss occurs through evaporation at the pool’s surface. This is why we size pool heating systems in relation to the pool surface area.
Where do we get our temperature information?
An unheated swimming pool’s water temperature will usually match the average air temperature for the preceding week. If the pool is warmer than the air after a cold front passes through, the pool will give up heat energy through evaporation until the air and water temperatures are the same.
Think of it this way: You run your air conditioner during the summer to cool your home. If you were to open all the doors and windows on a hot summer day, the indoor air temperature would rise to match the outdoor air temperature within a fairly short time. At some point, the indoor and outdoor air temperatures would be the same. Your pool goes through the same balancing act, only in reverse.
So the unheated pool temperatures you see on the this page are the same as the 10-year average air temperatures for each three-month season at the latitude and longitude of the reference city.
Our data comes from 10 years of NASA weather data. Unlike measurements taken at an airport, the NASA data represent an average for an area measuring one degree of latitude by one degree of longitude. Naturally, actual temperatures within this area will vary: a bit warmer in urban surroundings and a bit cooler in rural surroundings.