Which Option is Best to Make Your Pool Water the Most Comfortable
Unlike when you were 8 years old, the thought of doing cannonballs into an icy cold pool doesn’t sound all that appealing. Most people hate swimming in a cold pool and pool heaters provide warm comfortable pools to swim in and can even extend the swimming season where you live. Different size pools hold different amounts of water, meaning different size heaters are required to raise the water temperature and hold it steady. Sizing a heater properly means your pool water will heat to your desired temperature in a desired timeframe. An undersized pool heater will heat too slowly, and a severely oversized pool heater may end up unnecessarily driving up the cost of this big investment. So what size pool heater do you need? Read on to learn more.
Types of Pool Heaters
Before we jump into sizing your pool heater, we need to figure out which kind you have or want to purchase. There are three types of pool heaters and their “size” is determined by the output of BTUs. The standardized unit of measurement, BTUs (British Thermal Units), indicates the amount of heat energy required to raise the temperature of one pound of water by one degree Fahrenheit. The higher the BTUs, the more energy output is produced.
Solar
Out of these three kinds, solar pool heaters are the most environmentally friendly and, in most cases, the most economical as well. Solar heaters use the sun’s warmth to heat the pool by pumping the water through solar panels. In the long run, this is the least expensive way to warm up your pool, but the up-front cost is quite a bit more than it is for other kinds of heaters.
Gas
If you’re looking for the fastest way to heat up your pool, then gas is probably the way to go. There are models available in both propane and natural gas. Gas pool heaters are quite expensive and do cost a bit of money to run, but if you heat your pool infrequently, it might be a viable option.
Electric
This is by far the least expensive option in terms of up-front costs, but it is also the least efficient way to heat your pool. It is not the best option in cool climates or when you need a lot of heat, but if you’re looking for a subtle amount of heat, then this may be a good choice.
For the purposes of this article going forward, assume we are always discussing gas or electric heaters.
Ways to heat your pool
There are two ways a pool owner may choose to heat their pool. You can utilize “on-demand heating” where you turn off the heater when the pool is not in use and let the water cool down, then turn it on in advance of swimming to bring the temperature back up. The other option is “maintenance heating” where you continually run the heater and keep the pool water at a desired temperature. All pool heaters can do both, but you may want a higher-powered heater if you plan on letting the water cool between swims since you will need more power to heat it all again quickly.
Sizing your pool heater
Once you decide if you will be heating your pool “on-demand” or practicing “maintenance heating,” use these steps to further determine what size heater may work best for your pool.
1. Calculate the surface area
You might assume that when you are determining what size pool heater to buy, you’ll look at the pool’s gallon size or volume. Some people may use this number, but really the first step is to calculate the pool’s surface area which is the pool length times the pool width. While it is important to consider how many gallons the pool has to heat, it is better to consider the surface area the heat has to escape the pool. You want a heater large enough to compensate for the heat loss relative to the surface area it can escape from.
To calculate the surface area of your rectangular pool, multiply the length times the width. For a round or oval pool multiply ½ length x ½ width x 3.14.
For an example, let’s say your pool is 16’ x 32’ then your surface area is 512 square feet.
2. Divide surface area by 3
After you calculate the pool’s surface area, you will divide that number by three. The result is the minimal BTU size recommended for that particular surface area.
With the example of the 16’ x 32’ pool above, after dividing by 3 the result is 170. Therefore, the minimum size heater that is recommended for that pool is 170,000 BTUs.
This is just the recommended minimum size however. You can go with a higher BTU unit, but not lower. If the size was lower it couldn’t keep up with the heat loss to the surface and adequately replenish the heat to your pool.
3. Consider your variables
Now that you know the minimum BTU size recommended for your pool, you can assess some other variables to see if you need to go with a larger size. Some of these include but are not limited to the pool’s starting temperature, surrounding air temperature, desired water temperature, if you’re using a solar cover, and how quickly you want the water to heat.
As mentioned before, if you plan to heat your pool “on-demand” you will want a larger heater, but if you plan to maintain the heat you won’t need as much power. You will also want to identify what temperature you prefer to swim at (in degrees Fahrenheit). This establishes what performance you expect your heater to maintain under different environmental conditions.
If you’re using a solar cover, you may not need a higher-powered heater because your solar cover will keep heat inside the pool at night and prevent it from escaping at the surface.
Another important variable to consider is the ambient air temperature where you live. A pool in a hot climate will have different environmental conditions to overcome than a pool in a colder climate area. For the purposes of calculating what size of pool heater you need, you need to know what the coldest ambient air temperature will be when you still expect your heater to be keeping your pool warm.
Do I Need a Pool Heater?
Pool heaters aren’t an essential piece of equipment for your pool, but if you want to enjoy swimming in comfortable waters, they are an added bonus. If you live in an area that gets cold, or you’d like to keep your pool open slightly longer, then they’re worth every penny. Just because the surrounding temperatures are getting colder doesn’t mean you have to close your pool for the season. With the right size pool heater, you can swim comfortably and enjoy your pool regardless of the temperature outside.