What’s the best inground pool heater in 2021? During this global pandemic? Pool heaters are not the cheapest products you can buy but if you have a pool I’m certain you’ll be spending a lot of time in it this year. Where else are you going to go to escape? Basically your home is your oasis until the pandemic is over. It’s always stressful when you have to spend a lot of money in one go but if your heater isn’t working or you need an upgrade then you have to choose which road you want to take. In this article I assume that you’re already looking for the best pool heater for inground pools. Hayward and Pentair are still dominate brands but other manufacturers have entered the market to increase competition.
We go deep (pun intended) and look at gas inground pool heaters, as well as heat pumps and solar heaters. There should be something here for everyone. Another common question that we answer is : What size pool heater do you need? Don’t guess. We help you do the math.
Let’s take a Quick Look at this Hayward Heat Pump, which are far more energy efficient than traditional gas pool heaters and they require the outside temperature be above 55°F (12°C) to operate optimally.
► 140,000 BTU Heat Pump : Hayward 21404T
Features : (Hayward 21404T)
- Titanium Heat Exchanger – Excellent salt water and chemical corrosion resistance
- Exclusive ‘Ultra Gold’ Evaporator Coil corrosion resistant especially in coastal areas
- Quiet Operation – quiet backyard environment
- AHRI Certified Performance – Independent lab certified performance ensures value of purchase
- Round Design – Easily fits through gates and takes up less space on equipment pad
- 2in x 2 1/2in CPVC Union Plumbing Connections – Common union for installation or service, adapts to larger plumbing recommended for greater efficiencies
- Lighter Weight – Less than 250 lbs.
— Buy A Known Brand Pool Heater
► Pentair UltraTemp (460962) — 108,000 BTU Heat Pump
- 100% titanium heat exchanger assures corrosion-free performance for extra long life
- LCD control board displays an intuitive menu-driven read out with easy to follow full word messages…no more codes
- AutoSet (time clock over-ride) feature monitors water temperature and turns the water circulation pump on and off as needed to maintain desired pool temperatures
- Automatic defrost feature senses refrigerant temperature and prevents freezing, allowing the heat pump to operate at even lower temperatures
- Compatible with ALL automated control packages
- Long-life corrosion resistant plastic composite cabinet stands up to severe climates and pool chemicals
- Emerson Copeland Scroll® Compressor
- ETL listed for safe operation
- Thermostatic Expansion Valve (TXV) controls refrigerant flow for optimum efficiency and BTU output over a wider operating range
- Highest efficiency available, meets or exceeds existing codes and standards
- BTU and efficiency performance independently certified by the Air-Conditioning, Heating and Refrigeration Institute, AHRI
Before we get to the specific models, it’s important to know some basic information so you don’t waste your money. Remember, buying an inground pool heater might cause you some anxiety because of the price tag but if you view the purchase over the long-term; like a decade, it won’t seem so astronomical to pay. Owning a pool is expensive, much like owning a boat. I think the Summer of 2021 will be a season we never forget as we slowly move out of this global pandemic and step forward into a normal life. Nobody said owning a swimming pool would be cheap — and if they did, well, they lied to you.
It’s imperative that you buy a pool heater that’s high-quality and will last. Stick with known brands. I can’t stress that enough. You want to make sure you have a long warranty when you spend this much money. Also, reputable brands have a customer support phone line you can call. Cheap brands do not have a phone number because they don’t want to hear from you and they likely won’t be around in three years when your inground pool heater becomes defective. What are you going to do then? People don’t consider the price they pay when they buy cheap products. Don’t be tempted to go cheap with a pool heater. You’ll regret it.
Choosing the Right Inground Pool Heater
You might need a pool heater to heat your pool not only during the cold months but also during warmer months when you intend to use the pool into the night when it gets a little cold. Heating a large water mass takes a lot of time, money and energy, which is why you need to find a heater that’s efficient.
Two High-Quality Inground Pool Heaters for Homeowners.
This is an in depth guide meant to provide you with comprehensive information about how to choose a pool heater and we’ve also included a review of two series of pool heaters, which are categorized as low NOx emission heaters.
Factors to Consider
Is It Eco-Friendly?
NOx is a generic term for mono-nitrogen oxides, which are produced when oxygen, nitrogen and hydrocarbons react at high temperatures. When the oxides react with moisture, ammonia and other compounds, they produce nitric vapor, which when inhaled can damage our lungs. Inhaling the vapor can also worsen respiratory diseases or aggravate existing heart diseases. Make sure that you purchase a pool heater that specifically designed to reduce NOx emissions.
Which Type of Inground Pool Heater Do You Need?
Before selecting a pool heater, you should keep in mind that whichever type you choose, you should consider the availability and price of fuels in your neck of the woods. There are five types of pool heaters:
🌞 Solar Pool Heater | Smartpool WES601P
This is probably the cheapest type of pool heater to use. It does not have operating costs and it’s not noisy. It uses a free energy source and has no emissions so it’s considered to be eco-friendly. Unfortunately, this might not be the right choice for you if you live in a cool climate area. The heater requires direct sunlight in order to work but if you decide to install it, make sure you also install a backup heater.
Electric Pool Heater —
If you own a portable spa or a small therapy pool, this would be an ideal choice for you. However, while it may work well, it requires a substantial amount of electricity to run which makes it less than ideal for most pools.
Despite its small size, it’s expensive to install because it requires heavy duty wiring and circuit breakers with large amperage. On the bright side, they typically cost $2, 000 and do not release gases into the environment.
Electric Heat Pump
Hayward HeatPro Series | Read our Full Review
There are two types of heat pumps: water source and air source. Water source pumps transfer heat from water while air pumps transfer heat from the air to the water. They are relatively cheap to operate and you should expect to spend an average $50-$150 per month on operation costs.
They also considered to be eco-friendly since they have no emissions and are built to last. One of the biggest disadvantages of the electric heat pump is that it may not be effective in colder temperatures. It also takes a while to heat up an average or large-sized pool and the cost of purchase is high. Grid energy generation might emit greenhouse gases.
Natural Gas or Propane Heaters
This is the most widely used type of pool heater and is considered the best option. They heat up a pool relatively fast regardless of the air temperature. They are, however, expensive to operate and may not be as fuel efficient as other heating options.
On average, you should expect to spend about $500-$750 per year to fuel a natural gas pool heater. Don’t forget that you also need to hire a professional to install the unit which adds to the initial cost of the heater.
Wood Burning Pool Heaters
These are similar to outdoor furnaces and just like the other heaters, they require pumps to circulate the pool water. The two greatest disadvantages of the wood burning heater is that it is not Eco-friendly because you need to cut down trees to provide firewood and you also need to keep adding firewood every 60-90 minutes during the heating process.
So to summarize, if you live in an area with plenty of sunshine, the solar heater would be most convenient for you. If you only heat your pool occasionally, the gas heater would be ideal. If you are looking for fuel efficiency and minimum operating costs, then the electric heat pump or electric resistance pool heater would be a great choice.
Which Size Pool Heater Do You Need?
Okay, so we are going to do a little simple math here so that you get an idea of how things work. First, you need to know the capacity of your pool. The best way to do this is to use an online pool calculator and thankfully Pentair has an excellent tool to take the guesswork for you. I highly recommend using it : Calculate your Pool Volume.
Once you know how much water your pool has, we can get to the nitty-gritty of how much heating capacity you will need.
What is a BTU?
The British thermal unit (BTU or Btu) is a traditional unit of work equal to about 1055 joules. It is the amount of work needed to raise the temperature of one pound of water by one degree Fahrenheit (Physical analogue: one four-inch wooden kitchen match consumed completely generates approximately 1 BTU). In science, the joule, the SI unit of energy, has largely replaced the BTU… (Learn more on Wikipedia)
First, heating capacity for pool heaters is measured in BTU.One BTU raises 1 pound of water by 1 degree (Fahrenheit). In one gallon of water, there is 8.33 pounds of water. So if you want to heat up 30,000 gallons of water (that’s a 20’ X 40’ pool), you will have to calculate how many pounds of water there are.
As per our example: 30,000 X 8.33= 249, 900 pounds.
To find out how many BTUs you need per hour to raise the temperature of your pool by one degree in a day, you will need to divide the total pounds of water by 24hours.
249, 900 / 24 = 10, 412
So you will need 10,412 BTUs per hour for a 1 degree rise in 24 hours.
Let’s say your pool is at 60 degrees and you want to increase the temperature by 20 degrees. We already know that 1 BTU increases temperature by 1 degree and we already know that you need 10,412 BTUs per hour to increase the heat in your pool by 1 degree in 24 hours. Now we need to find out how many BTUs will be needed to increase the temperature of your pool by 20 degrees.
10, 412 X 20 = 208, 240 BTUs
So from the calculations, you’ll need to purchase a pool heater that is capable of at least 210,000 BTU per hour. But, if you want to heat up your pool super-fast without using too much fuel, you’ll need to purchase a higher capacity heater.
Reviews | Best Inground Pool Heater
Out of all the different types of pool heater, natural gas heaters seem to be the most popular. We have, therefore included a review of the Pentair and Hayward series of pool heaters.
Pentair MasterTemp Pool Heaters
You have probably heard about the quality and reputation of Pentair aquatic systems. They manufacture a variety of pool products that include: automation systems, lights, cleaners, heaters, filters, pool pumps and much more.
We will focus on two types of pool heaters, with a focus on the most popular and common size for each series — Pentair 460736 (Natural Gas) and the Pentair 460737 (Propane). These are both 400,000 BTUs, which homeowners seem to buy in droves.
Natural Gas Models:
- Pentair 460736 | 400,000 BTU | Natural Gas
- Pentair 460805 HD | 400,000 BTU | Heavy-Duty
- Pentair 460775 ASME | 400,000 BTU
- Pentair 460734 | 300,000 BTU
- Pentair 460771 ASME | 250,000 BTU
- Pentair 460732 | 250,000 BTU
- Pentair 460730 | 200,000 BTU | Natural Gas
- Pentair 460792 | 175,000 BTU
There are some variations to the heater, depending on the model.
- HD : Stands for Heavy-duty, which means it has a Cupro-Nickel Heat Exchanger.
- ASME: Designed for commercial applications, with enhanced features.
- Upgrades to thermal regulator include a governing stainless steel sleeve for better wear protection.
- All internal components of the bronze header are now plastic for lightweight, corrosion and wear protection.
- Ignition Control Module includes more diaphragm spring force for better gas control and robust operation.
- Fuller pre-mixed system with highly efficient air and gas mixture allows for faster heat up times.
Common Features —
Compact design enables it easy to fit in small spaces. A completely pre-mixed system with an efficient air and gas mixture allows your MasterTemp to heat up fast.
- Hot surface ignition (no pilot light) and push-button, digital controls. Easy to operate and monitor a snap.
- Rotating digital display makes it easy to view regardless of how MasterTemp is positioned.
- MasterTemp is ultra-quiet and won’t be noticeable when you’re lounging in your pool. Durable, rustproof composite exterior is engineered to handle the heat and weather.
- Eco-friendly, MasterTemp is low NOx emissions and outperforms industry standards.
- Includes a variety of safety features, including: a water pressure switch that senses the pump is running to prevent overheating; high limit switches assure the heater turns off if water temperature exceeds factory set limits; manual gas shut-off when service is required; stack flue sensor also guards against overheating.
- Approved for installation on combustible surfaces.
A Bigger Inground Pool Heater is Better
This isn’t a marketing ploy, it really is true. Bigger is better when it comes to buying an inground pool heater.
Remember, it’s always better to get an inground pool heater that’s a little more powerful than what you need rather than ‘under-powered.’ A higher rated pool heater (BTU’s) will enable your pool to be heated at the correct temperature without straining and stressing the heater.
For example, if you buy a 400,000 BTU pool heater and your pool size requires you to have a 300,000 BTU pool heater, well, that means you can run the 400,000 BTU inground pool heater at a maximum of 75% of it’s total power at any given time. This will mean that the unit is never being overburdened, allowing it to run cooler, be more efficient and in the long run, will actually last longer than if you bought the exact correct size.
All of these Pentair MasterTemp inground pool heaters are essentially identical. Since they belong to the same series, the have the same main features, so bear this in mind when reading the information. The only difference is the size in terms of BTU’s, which directly affects the size of pool it can heat and also the overall size (dimensions) of the unit. As you would expect, a higher BTU rating heater translates to a heavier and larger (in dimensions) unit.
At first glance, this heater doesn’t look like much at all. In fact, it doesn’t look like a cutting edge piece of pool heating technology that’s going to make your life easier. But since we are talking about a pool heater here and not a show piece for your back yard, we will put these reservations aside.
The Pentair 460736 is a natural gas pool heater that’s proven to be reliable, energy efficient and long lasting for home owners. It comes with an easy digital display that makes it easy to operate and monitor the heater. Unlike other pool heaters, it is engineered to be ultra-quiet.
The control panel has five led lights that will show you the status of your system and will indicate when your pool heater needs to be serviced. It also displays the water temperature. The system is compatible with control systems from other manufacturers so you don’t have to worry about mixing and matching.
When you compare it to the Pentair MasterTemp 460805, you’ll find that it’s made of standard copper material while the Pentair 460805 is made of a copper-nickel alloy that’s much stronger. Nickel significantly improves the overall corrosion resistance and strength of copper. Just to give you a clearer picture of how cool the alloy is, imagine a metal that can bend, stretch or deform under stress but still maintain it’s strength. The Pentair 460805 will obviously cost you more money.
But if you are an average homeowner, the Pentair 460736 will serve you just as well. If, however, your pool gets a lot of consistent usage all year round or you are running a salt-water system, we recommend you get the Pentair 460805.
What People Like Most About the Pentair 460736?
Most people who have bought the pool heater appreciate the fact that it is 100% certified for low NOx emissions. It’s nice to know that you have installed an energy efficient and safe system in your home. They also appreciate that it heats up the pool in no time thanks to the massive 400, 000 BTU propane heating system.
What customers don’t like about the Pentair 460736
The high cost of this machine probably turns many people off since there are cheaper products in the market out there. The upside is that it performs better than pretty much any of those cheaper models so you will get value for your money.
Pentair 460737 | Propane Gas
If you are living in states with low NOx emission standards, then this is definitely one of the best pool heating systems around. It’s smaller than most other high performance heaters out there and it’s also quite easy to install.
You’ll notice that it’s engineered to run quietly in the background unlike other heating systems which are loud and always humming in your ear.
You also don’t need to wait for hours on end just to get your pool heated. The Pentair comes with a fully pre-mixed gas and air mixture which heats up the water super-fast.
It doesn’t come with a pilot light, which are known to blow out at the worst possible times. It actually has a hot surface ignition that fires up the heater with the press of a button. It’s also easy to operate thanks to a rotating display and convenient indicator lights.
What People Like Most About the Pentair 460737
Most people who bought this heater appreciate that Pentair built it with safety in mind. They installed a stack flue sensor, a water pressure switch and a high limit switch which ensure that the system never overheats and it always functions properly. They also like how eco-friendly, reliable and convenient it is to use. The Pentair 460737 can heat up a pool in a very short time regardless of how big it is.
What People Don’t like
The fact that the system uses propane gas makes it a little more expensive to operate than other smaller units.
How Do They Differ From the ASME Models?
ASME stands for American Society of mechanical engineers. ASME heaters are tested after manufacturing to comply with ASME quality control standards. They also have a superior warranty. However, just because a pool heater doesn’t have the ASME code symbol, doesn’t mean it is inferior or less safe. Your local building codes might, however, require you to install a pool heater that bears the ASME code symbol for units rated 200, 000 BTU or higher.
Documents Pentair MasterTemp series.
- View or download the MANUAL.
- View or download the BROCHURE.
- View or download the INSTALLATION CHECKLIST.
- View or download the Bypass access plug kit (472648z).
Universal H-Series Pool Heaters
- Standard Cupro nickel heat exchanger for superior value and reliability.
- Patented polymer header and bypass valve design for the ultimate in hydraulic efficiency and reliability.
- Hayward Universal design for easy and versatile professional installation.
- Environmentally responsible low NOx emissions to meet or exceed air quality emission standards in all Low NOx regions.
- 83% thermal efficiency for energy-efficient performance.
- Universal design independent left- or right-side electric, water and gas connections ensures the easiest and most versatile installation.
- 2″ x 2½” CPVC unions and plumbing ﬁttings.
The universal H-series swimming pool heaters are a great choice if you are looking to upgrade your current heating system or you are looking to install a new one.
We review the H400FDP later there are a wide range of models powered by either natural gas or propane, and they all share the same great features. Here is a full overview of all the Hayward H-series gas pool heaters:
Natural Gas Models:
- Hayward H150FDN — 150,000 BTU | Width 21″
- Hayward H200FDN — 200,000 BTU | Width 25″
- Hayward H250FDN — 250,000 BTU | Width 28″
- Hayward H300FDN — 300,000 BTU | Width 30″
- Hayward H350FDN — 350,000 BTU | Width 33″
- Hayward H400FDN — 400,000 BTU | Width 36″
- Hayward H500FDN — 500,000 BTU | Width 41″ (requires 1.0″ Gas Line connection)
The model number for the propane gas heaters end in “FDP.”
- Hayward H150FDP | 150,000 BTU | Width 21″
- Hayward H200FDP | 200,000 BTU | Width 25″
- Hayward H250FDP | 250,000 BTU | Width 28″
- Hayward H300FDP | 300,000 BTU | Width 30″
- Hayward H350FDP | 350,000 BTU | Width 33″
- Hayward H400FDP | 400,000 BTU | Width 36″
- Hayward H500FDP | 500,000 BTU | Width 41″ (requires 1.0″ Gas Line connection)
Choosing the Right Hayward Pool Heater
Read the press release for the introduction of the 500,000 BTU heaters.
Documents for the H-Series Pool Heaters / View or download by clicking the links below:
Purchasing the H400FDN won’t save the earth from climate change just because it is a low NOx emission heater. But you will rest easy knowing you made the best choice possible.
The system has stainless steel burners, insulated fire tile combustion chambers and corrosion resistant heat exchangers. All these help the system to trap heat more efficiently. The LED control panel is easy to understand and you can monitor the overall performance of the heater.
If you have a pool with salt water this would be the right heater for you because it is made of CuproNickel, which is one of the strongest metal alloys out there.
Many variables can affect the amount of time and even the way your pool gets heated. So what Hayward has done with this model in order to get rid of these variables, is they have included a forced draft combustion system. The system moves air through the combustion chamber at a precise flow rate thereby eliminating all variables that can affect heating performance.
High flow conditions can encourage erosion that ultimately starts to eat up material used to make the heater. But, the H400FDN has a patented polymer header design that not only protects against the damaging effects of erosion but also provides superior hydraulic performance to save energy.
What People Like About the H400FDN
Apart from being eco-friendly, it heats up the pool super fast. It can raise the temperature of a 25, 000-gallon pool by 10 degrees in 25 minutes.
What People Don’t Like
Seems like there are people who feel the heater is too loud when it’s running. The upshot is that if you are not sensitive to noise, you can go ahead and purchase it as it does its job really well.
The H-Series pool heaters are identical so a review of the H400FDN applies to the H400FDP. This means that all the features for the H400FDN are also true for the H400FDP. The only notable difference is in the size, weight and BTU.
For starters both the H400FDN and H400FDP are a powerful 400, 000 BTU, have 83% thermal efficiency and a width of 36 inches. The indoor vent pipe diameter for the H400FDN is 6 inches while for the H400FDP it’s 8 inches.
To learn more read our in-depth review of the Hayward H400FDN.
VIDEO | Hayward H-Series Installation, Start-up & Troubleshooting
VIDEO | Learn more about Hayward
Unique rounded design make it compact and lightweight.
We’ve dedicated a full article to the Sta-Rite Max-E-Therm pool heater so to avoid repeating ourselves we recommend reading our full review. It’s a fantastic inground pool heater and a good option to consider.
Comes in a variety of sizes:
- Lightweight – Lightest heater in its class
- Best in class energy efficiency*
- Compact Design – Ideal for retro-fit installations
- Easy to Switch – Change gas sources with installation of separate orifice
- Environmentally Friendly – All units are low NOx
- Rustproof Housing – Sleek, matte black enclosure is made of Dura-Glas – an exclusive Sta-Rite material that handles the heat and weathers the elements
- Lower Operating Costs – 84% efficiency rating – rated first in its class for highest energy efficiency
- Custom or Retrofit – Direct-connects to Sta-Rite System:3 Mod Media filter or easily fits other systems
- Certified for outdoor and indoor installations.
Spa and Pool Chart for the Max-E-Therm | Inground Pool Heater