How to Buy The Best Pool Heater

Why do you want to buy a pool heater? Do you hate swimming in a cold pool? Perhaps you just want to extend the pool season so you can swim a little early in April and keep it open until October, or even November. How does a nice Thanksgiving weekend swim sound?

Whatever your reasons, you have three main options available to you: solar pool heaters, gas pool heaters, and pool heat pumps. The key to choosing the right one for you is knowing how they work, how to find the right size for your pool, the pros and cons of each, and how much money you’ll spend—or save.

Pool Heater Thermal Units

BTU, which stands for British thermal unit, is how pool heaters are sized. One BTU (sometimes also written as Btu) is the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.

Pool heater outputs range from 75,000 BTU to 450,000 BTU. The amount of heat generated often depends on the type of pool heater you have.

Solar Pool Heaters

Solar pool heaters work by pumping the water from your swimming pool to your filter, and partially diverting it through solar collectors that warm the water before it goes back into the pool.

Types of Solar Pool Heaters

Glazed collectors are more expensive, but also more durable than unglazed collectors. Both include freeze protection to protect against colder weather areas.

How Much Does a Solar Pool Heater Cost?

It usually costs between $3,000 and $4,000 to buy and install a solar pool heating system.

How to Find The Right Size Solar Pool Heater

The surface area of your solar collector should equal around 75% of your yard, more if you keep your pool open year-round—up to 100%. You can preserve yard space if your home’s roof is large enough to accommodate the appropriate number of collectors.

For example, if you have a 16′ x 32′ inground swimming pool in the southern United States, you would need a 100% equal surface area. So multiply 16′ by 32′ to get the square footage of 512. This means you’ll need 512 square feet of solar collectors.

But if the same size pool is located in the northern United States, which only has the pool open for 6 months out of the year (if you’re lucky), then you’d only need about 75% of the surface area, equaling 384 square feet of solar collectors.

You’ll also need the right size pool pump for a solar heating system. If you’re replacing your current heater with a solar system, you may need a larger pump or a separate pump to help push the water through the solar collectors.

Solar Heater Pros

Solar Heater Cons

Gas Pool Heaters

Fairly inexpensive to operate, gas pool heaters use natural gas or propane. Water passes through while a combustion chamber burns and warms the water before returning to the pool. In other words, the water passes through a burning hot tube, then back to your pool.

Gas heaters are also efficient and will get the job done quickly. If you live up north where temperatures are cooler, you can heat the pool up quickly, and then use a solar cover to maintain the heat to cut down on operating costs.

Natural Gas or Liquid Propane

The type of fuel you use will depend on the availability and the price of fuel in your area. The good news is both types of heaters usually cost about the same.

If your home has natural gas, you can also use it to heat your pool. If you don’t, you’ll have to buy a large, ugly propane tank and install in your backyard, which will need to be filled up regularly.

On the other hand, propane is usually 2.5 times more expensive than natural gas, depending on supply and demand.

Millivolt or Electronic Ignition

Millivolt means you have a small amount of gas that keeps a pilot light lit so that it’s always available to fire up while an electronic ignition lights the burners with a spark, just like a gas grill.

We recommend going with an electric ignition so you use less fuel and don’t risk a gas leak.

Low NOx vs. Normal Emissions Pool Heaters

A “Low NOx” gas pool heater is designed to release low emissions, which also makes them more efficient than regular pool heaters. This also means your pool will heat more quickly.

If that wasn’t enough of a sell for Low NOx, they also meet the NOx Emission standards set by the California South Coast Quality Air Management Commission for 2001 and the Texas Natural Resource Conservation Commission Code. So if you live in those two states, you’ll need a Low NOx heater anyway.

Other Gas Pool Heater Features

How Much Does a Gas Pool Heater Cost?

On average, the cost to run a natural gas pool heater is $300-$600 per month, and possibly even more for a propane heater.

New inground pool gas heaters can cost between $1,500 and $3,500, depending on the size, type, and brand.

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How to Find The Right Size Gas Pool Heater

Just like any pool heater, you need to first know the surface area of your pool in square feet. You’ll also need to figure out the average air temperature in your area.

  1. Decide what you roughly want your pool water temperature to be and what the average temperature outside will be during the coldest month.
  2. Subtract the average temperature for the coldest month from the temperature you want your water to be to figure out the temperature rise needed.
  3. Calculate the pool surface area in square feet by multiplying the length and the width of your pool.
  4. Then, use this formula to figure out the BTUs you’ll need your heater to put out: pool area (sq. ft.) x temperature rise x 12.

For example, the average temperature in New Jersey during the month of October is 65°F. If you own a 16’x32′ inground pool in New Jersey, and you want the temperature of your pool to be 80°F all the time, the temperature rise calculation is:

80 (degrees) − 65 (degrees) = 15 degrees in temperature rise.

Using the BTU formula, the calculation would be:

512 (pool surface area in square feet) × 15 (Temperature Rise) × 12 = 92,160 BTUs of heat needed to be generated by your new pool heater.

Frustrated by adding chemicals and trying to keep your pool clear all the time?

We cut out all the confusion of pool maintenance in this easy-to-read illustrated ebook and video course. It'll help you save $100 right away on pool care!

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The Pool Care Handbook

Gas Pool Heater Pros

Gas Pool Heater Cons

Do You Have Gas?

We’re not trying to be too personal. We’re talking about gas lines running to your home.

Before you buy a gas heater, it’s good to know the distance from the gas meter to where the heater will be installed. Even if you’ve sized the heater correctly, depending on the distance from the meter, the gas line size may not support the heater.

Important factors to consider:

By the time you’ve spent up to $2,000 for a heater, you don’t want to learn it’s going to cost $500 to $1,000 to run a new gas line. Knowing the correct size of the heater to purchase, distance, and gas size beforehand will save you time, trouble, and money. Contact your utility company to get more information before you buy a gas pool heater.

Pool Heat Pumps

Water from your pool passes through the heat pump, just like a gas or solar heater. The heat is created by a fan that takes the outside air and directs it over an evaporator coil. Liquid refrigerant inside the coil absorbs the heat from the air and turns into a gas.

The warm gas heads over to a compressor, which increases the heat, then makes its way through a condenser. The condenser takes that hot gas and adds it to your pool water.

As the hot gas passes back through the condenser, it transforms back into a liquid and heads back to the evaporator to start the whole process again. Pretty cool, huh?

How Much Does a Pool Heat Pump Cost?

They can cost less to run than gas heaters, but may also cost more up front because of their unique heat-generating ability. They also last longer than gas heaters, too.

Pool heat pump prices range from $2,000 to $3,000, and can go as high as $4,000 to $5,000.

Of course, the cost to run it will depend on where you live. For example, if you live in a warmer climate, it will cost less to run.

Maintaining an outdoor pool in Florida at 80°F (27°C) year-round can cost about $1,400 annually, but only about $300 if you use a solar cover.

In the Northeast United States, maintaining an outdoor pool at 80°F (27°C) from May to August costs about $1,100 annually, but only around $120 with a solar cover.

How to Find The Right Size Pool Heat Pump

Just like a gas pool heater, heat pump pool heaters are rated by BTU output. However, they’re also rated by horsepower (hp). Standard sizes include 3.5 hp/75,000 BTU, 5 hp/100,000 BTU, and 6 hp/125,000 BTU.

To calculate an approximate heater size for an outdoor swimming pool, follow the same steps as above for finding a gas pool heater size.

Pool Heat Pump Pros

Pool Heat Pump Cons

Add a Solar Cover and Digital Thermometer for Efficiency

If you invest in any pool heating system, we highly recommend you also invest in a solar cover or liquid solar cover. If you imagine your pool as a giant cup of coffee that’s heated up by the pool heater, then a solar cover would act as the lid on the cup, helping to keep that heat in.

A digital thermometer is another good investment so you can keep an eye on your water temperature to help you maintain the heat. It will also help you determine what your preferred pool temperature is.

While you may assume 80°F (27°C) is right for you, your digital thermometer might advise otherwise, which could also save you money when heating your swimming pool.

What’s the Best Pool Heater for You?

Choosing the perfect pool heater will depend on where you live and what type of heat source is available to your home.

We suggest:

If you’re concerned about your budget, we recommend a pool heat pump with a solar cover. It may be a heavy investment up front, but it will pay for itself in the long run.

Best Pool Heaters

We’ve put together a list of some of our favorite pool heaters to help you find the perfect heater for your backyard water playground.

Hayward H400FDN Universal H-Series Low NOx Gas Pool Heater

Providing 400,000 BTUs of heating power, the Hayward H400FDN can heat just about any pool of any size. The system is designed for very low emissions and efficient running so while your gas bills may go up, they’ll still be lower compared to other heating systems.

This gas pool heater has a standard cupronickel heat exchanger for superior efficiency. Its patented polymer header and bypass valve are designed for hydraulic reliability. Its environmentally responsible low NOx emissions If you click this link and make a purchase, we earn a commission at no additional cost to you. meet or exceed air quality emission standards in all low NOx regions.

Hayward H400FDN Universal H-Series 400,000 BTU Pool and Spa Heater Price: $2,699.00 Hayward H400FDN Universal H-Series 400,000 BTU Pool and Spa Heater If you click this link and make a purchase, we earn a commission at no additional cost to you. Last Updated: 11/01/2019

Raypak Natural Gas Pool and Spa Heater

Its compact size makes it ideal for both inground and above ground pools. The Raypak is equipped with a standard 120v 3-prong power cord that can easily be converted to 220v, and features an analog thermostat dial.

A soft opening gas valve makes lighting the pilot easy and safe, and the system delivers reliable and fast heat. The thick-walled copper heat exchanger is corrosion resistant and features a built-in bypass valve that balances the flow and adjusts for a wide range of pump sizes If you click this link and make a purchase, we earn a commission at no additional cost to you. and flow rates. It comes with a one-year warranty.

Raypak Natural Gas Pool and Spa Heater - 105,000 BTU Price: $1,234.33 Raypak Natural Gas Pool and Spa Heater - 105,000 BTU If you click this link and make a purchase, we earn a commission at no additional cost to you. Last Updated: 11/01/2019

Hayward HP21404T HeatPro Titanium Heat Pump

Designed for maximum heat transfer, efficiency, and reliability, this Hayward pool heat pump puts out 140,000 BTU for reliable, even heating If you click this link and make a purchase, we earn a commission at no additional cost to you. . It incorporates titanium counter-flow heat exchangers for optimal performance, even in harsh conditions. It also has heavy-duty, super-quiet scroll compressors and stainless steel hardware.

Its injection-molded, UV-resistant body panels are impervious to rust and deterioration. The evaporator fin is corrosion resistant as well. The round design makes it fit easily through gats, and it takes up less space on an equipment pad.

Hayward HP21404T HeatPro Titanium Heat Pump - 140,000 BTU Price: $4,225.00 Hayward HP21404T HeatPro Titanium Heat Pump - 140,000 BTU If you click this link and make a purchase, we earn a commission at no additional cost to you. Last Updated: 11/01/2019

Smartpool S601P SunHeater Solar Pool Heating System

With just 80 square feet of solar panels, this pool heater system can be mounted on a roof If you click this link and make a purchase, we earn a commission at no additional cost to you. . The polypropylene heat collector raises pool water temperature by 6°F to 10°F (4°C to 6°C). This system requires an installation kit If you click this link and make a purchase, we earn a commission at no additional cost to you. , which is sold separately.

Smartpool S601P SunHeater Solar Heating System for In Ground Pool Price: $198.99 Smartpool S601P SunHeater Solar Heating System for In Ground Pool If you click this link and make a purchase, we earn a commission at no additional cost to you. Last Updated: 11/01/2019

Is It Getting Hot in Here?

Just because the temperatures are getting colder doesn’t mean you have to close your pool for the season. With the right pool heater, you can swim comfortably and enjoy your pool regardless of the temperature outside.

Who says winter can’t be pool season?

Happy Swimming!

Frustrated by adding chemicals and trying to keep your pool clear all the time?

We cut out all the confusion of pool maintenance in this easy-to-read illustrated ebook and video course. It'll help you save $100 right away on pool care!

Click here to learn more
The Pool Care Handbook

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