Modern heat pumps are nothing short of technological miracles. The models made nowadays are more powerful, more efficient, and more affordable than at any other point in history. However, they’re only capable of doing their job properly if the consumer has done their job and bought the right one for their needs. If they purchase a heat pump for their pool that’s too small, then it’s not going to be able to properly heat it. If they purchase one that’s too big, then it’s not going to be as efficient. Therefore, the consumer needs to do their homework and choose the best one for their needs.

Finding the right size heat pump for your needs is really just a matter of comparing your needs and the size of the pool with a heat pump model. First, you’re going to want to come up with an approximate size for your heat pump and then narrow it down to a more specific model by considering the heat pump’s efficiency. To show you how to do that, we’re going to go through the procedure for choosing a heat pump step-by-step.

Step One: Determine The Pool’s Area

The first step to choosing the right heat pump for your pool is to figure out your pool’s area. To do that you’re going to have to measure the pool and then do a little bit of math. Don’t worry, the trickiest part of this process is figuring out the area of nonstandard pool sizes. For square or rectangular pools, it’s as simple as multiplying the width by length, and for round pools, it’s simply a matter of determining the diameter and squaring it, and then multiplying it by PI (3.14) to come up with the surface area. For example, a square pool that’s 10×10 feet has a surface area of 100-feet, and a 24-foot round pool has a total of 452.16 square feet (12x12x3.14=452.16). Once you have your surface area, write it down for later reference.

Step Two: Determine The Average Temperature Of The Coldest Month

The next thing that you’re going to have to determine is the average temperature of the coldest month in which the pool is going to be used. This information can easily be looked up online for most areas, but if you’re having trouble locating the data for your area, then you can calculate your own mean monthly temperature. To calculate this number, take the temperature data for the daily mean temperature of the month, adding it together, and then dividing it by the number of days in that month. That’s your mean monthly temperature. Just remember, you only need the mean monthly temperature for the coldest month in which the pool is used, not the coldest month of the entire year.

Step Three: Figure Out The Pool’s Temperature Rise

The next thing that you’re going to have to determine is what temperature you want your pool’s water to be, and then once that’s been figure out, the temperature rise of the pool. The pool’s temperature rise is the difference between your desired temperature and the temperature of the coldest month’s mean temperature, so subtract the average mean temperature of the coldest month from the desired pool temperature. Write this number down because you’re going to need it for your calculations.

Step Four: Do Some Necessary Calculations

Now that you have the pool’s Temperature Rise and the pool’s Surface Area, then you can now figure out the BTUs an hour that you’re going to need. Take the pool’s surface area, multiply it by the temperature rise, and then by 12 to come up with the BTUs per hour needed (Pool Area X Temperature Rise X 12).

It should be noted that this formula is based on a 1-degree to 1.25-degree Fahrenheit temperature rise per hour and with an average wind speed of 3-3.5 MPH on the surface of the pool. If you need a 1 to 1.5-degree temperature rise per hour, then multiply the formula by 1.5. If you need a 2-degree temperature rise per hour, then multiply the number by 2.

Some Back Of The Envelope Figures

Not everyone is going to want to go through the trouble of following the above steps to figure out how many BTUs an hour they need. Some people just want some back-of-the-envelope figures that allow them to quickly determine what size heat pump they might need without having to do a lot of research. For these people, we’ve come up with the following figures for people living in areas that have a mild climate.

  • 1,000 square-foot pool area = 2 ton pump
  • 2,000 square-foot pool area = 4 ton pump
  • 3,000 square-foot pool area = 6 ton pump

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