Swimming Pool Heat Pump Sizing
Heating the water in your pool can make swimming more enjoyable for everyone.
Available in different types and sizes of heaters, heat pumps are an energy-efficient and efficient solution for heating pool water.
However, if you decide to go electric, you need to figure out how to choose the right pool heater pump size for your pool.
Why is pool heat pump selection important?
A heat pump works by sucking in warm air from the outside environment and injecting it into the pool water.
Measuring output in BTU, it runs on electricity, so it takes longer to heat a pool than a gas heater.
Note: British Thermal Unit (BTU) is a unit of measure for measuring thermal (thermal) energy. Electric heat pumps have BTU ratings between 50,000 and 150,000. Calculating the amount of BTU you need will help you size your pool heater. Smaller in-ground and above-ground pools can use a 50,000 BTU heat pump, but if you have a large pool, you will need a larger one. A small pump on a large pool means that the heating rate is slow and may not even reach your target temperature.
In general, you should size your heat pump as much as possible. You'll never regret going too big, because doing so means heating the pool faster without having to run the heater as much.
That being said, there are still a few things you should consider when purchasing a heater for your pool, so let's talk about those.
How to Size Your Pool Heat Pump
The size of the pool, outdoor temperature, humidity levels, and air volume can all affect how quickly a heat pump can heat water.
Properly sizing your heat pump can prevent these external influences from becoming a determining factor in water temperature.
There are two ways to determine the proper pump size:
1. The easy way
The table below shows the typical amount of BTU required when using a heat pump. This makes it easy to choose the right pump for the amount of water in your pool.
Based on this information, if your pool has 15,000 gallons of water and you want to use a 120,000 BTU heat pump, you absolutely can. This will not be overkill, but will heat the water in less time.
2. Precise way
If you want to know your heater size, first you need to determine the amount of increase required for the desired temperature.
For this example, we'll say the pool's temperature is 65°F, and we want it to rise to 80°F -- an increase of 15°F.
Second, you need to find out the surface area of the pool. We will be using a 16 x 32 foot pool with a total area of 512 square feet.
Now, calculate the appropriate value using the following equation:
(surface area) x (temperature rise) x 12 = (minimum BTU required)
512 x 15 x 12 = 92,160 BTUs
Based on these calculations, you need a heat pump capable of outputting at least 92,160 BTU to raise the temperature in a 16 x 32 pool by 15°F.
For reference, a 16 x 32 pool has about 15,000 gallons of water.
Looking at the chart above, we can see that a 15,000 gallon pool would require a heat pump with 90,000 BTU, which is exactly in line with our 92,160 BTU figure.
If you're still unsure about choosing the right size heat pump, ask yourself the following questions:
1. How fast do you need to heat the water?
Heat pumps have BTU outputs ranging from 50,000 to 150,000. The higher the output level, the faster your pool will heat up. If you decide to output 100,000 BTU in the middle, it will still heat the pool, but it will also take longer.
2. Do you have any electrical appliances you need?
Heat pumps require a lot of electricity to run, which is one of their main drawbacks, as it can take a big toll on your wallet (though they're still cheaper to run than gas heaters). You should also make sure you have the correct electrical settings, as heat pumps require 50 to 60 amps.
3. What is your desired water temperature?
Most pool owners want warm water between 82°F and 86°F. With heat pumps, they can only produce so much heat, and due to their BTU output levels depending on the outside temperature, will eventually peak (especially with smaller pumps). In general, though, you should be able to heat your pool to 82°F on warm days.
With a heat pump, keeping the water warm can reduce electricity usage. You should ask yourself the following questions:
1. Are you using a solar cover?
A solar cover is a must. Heat escapes primarily from the surface of the pool water. The lid absorbs heat so you can use less of the smaller pump. They also prevent water from evaporating so you don't have to spend more to refill your pool. There are several variations of solar covers: large bubble wrap blankets, smaller, interconnectable solar solar rings, or chemical liquid solar covers.
2. How often do you swim?
If you want to maximize the heat in your pool and keep your electricity bills low, you should only leave the pool uncovered for about 2 hours a day. Of course, you can use the pool longer, but after 2 hours you will have to run the heater to replace the lost heat.
3. In what month do you swim?
Electric heat pumps work best during the warmer months. This is because they take warm air from the outside environment and inject it into the water. Traditionally, heat pumps run well from May to September. But once the weather drops to around 50°F, it's pointless to run them because there isn't enough heat in the air to transfer to the water.
4. How much are you willing to pay?
Pool heat pumps are much cheaper to run (about half as much) than gas pool heaters, but they also have a much higher upfront cost. Not only that, but if you live in an area with expensive electricity, a heat pump may not be the most cost-effective option.
Size really matters
As with all pool heaters, if you get big, you are gold.
A smaller pool heater pump size isn't necessarily detrimental, but you'll have to run it longer and may have problems keeping your pool warm.
Using the chart or calculation above, you can work out the minimum heat pump size required for your pool, and if you prefer, you can go larger for faster heating times.
What else do you need to know about heat pumps?
The choice of location is also important as heat pumps need a lot of air to work properly! For this reason, it is necessary to find a place suitable for fresh air when indoor operation does not work in most cases.
The heat pump itself is then integrated directly into the filter loop, after the filter system and before the chlorinator (if installed).
High-quality heat pumps are equipped with anti-corrosion heat exchangers, so any pool water can be heated, whether using chlorine, bromine, ozone or chlorine-free products. Can also be used in saltwater pools.
For all pools, other factors need to be considered, including solar gain, wind factors, and evaporative losses. This article aims to provide some insight into one approach to sizing.