2021 Reviews — Best 400,000 BTU Pool Heater? — Natural Gas

The Pentair MasterTemp 460736 and the 460805 MasterTemp are two of the best 400,000 BTU pool heaters for 2021. Both heaters are well-established with a long history of satisfied customers. We look at these popular 400K heaters later, but the big question is : Should you buy a pool heater online? You’ll get the answer later. My one piece of advice that you should take is to make sure you have your pool heater professionally installed. Many people fail to invest in a proper installation, then complain when it fails them or doesn’t work properly. Don’t cheap out with pool heaters. Do it right!

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You’ve been warned. These are expensive and complex machines. If you overlook one thing it can cause your system to fail and ruin the heater itself. Don’t risk doing it yourself. Just hire a professional to install it.

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Moving on. Do you need propane or gas?

Also available is a propane model — Pentair 460737 MasterTemp. Most manufacturer’s sell natural gas and propane versions of the same model, or they include conversion kits. Check the features carefully. Pool heaters are packed with advanced features, and engineered to last for a long time.

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Your 400K Pool Heater Options for 2021 —

Nobody wants to swim in a cold pool — unless it’s 100°F. If you own a pool, you need a heater. A 400,000 btu pool heater is ideal for pools over 40,000 gallons. But you should also know that it’s always better to buy a larger pool heater so you’re not running your heater at 100% all the time. This makes it run quieter, last longer and because of larger size, it will heat your pool quicker.

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Editors’ Picks : Best 400K BTU Pool Heaters

Most of these pool heaters are available in Natural Gas & Propane

Quality Brands, History Matters

If you’re curious about the reputation about these two brands — Raypak was founded in 1947 by Al Whittel. They’ve been in business over 70 years. For comparison, Hayward has been in business over 80 years. Basically, these are two very reputable brands with a rich history of manufacturing to the highest standards.

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Overview : 400K Pool Heaters

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I’m sure you know that pool heaters are not all made to the same standards. You do have a few fantastic options available, so let’s take a look at them before discussing heaters in more detail:

NOTE from EDITOR : Some of these heaters may not be available at the moment, as I’ve noticed that fewer pool heaters are being sold online nowadays. I believe it has to do with the warranty. Retailers don’t want to deal with pool heater returns. These are big and expensive, making it costly to handle returns.

Make sure that you are getting a full warranty when purchasing online. I think that most consumers aren’t aware that the warranty may be void if you buy the heater online and you install it yourself. To be safe, always have it installed by a certified technician so there’s never any doubt as to the quality of the installation and blame can never be directed at you.

In addition, ensure that you get the full warranty. If not, you’re better off buying locally and having it installed by the company you buy it from. If anything goes wrong they can simply drive over and fix it. Think carefully before buying a pool heater online.

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Natural Gas : Pentair 460805 HD — MasterTemp Pool Heater

PROPANE :  Pentair 460737 MasterTemp

Natural Gas : Hayward H400FDN — Universal H-Series Pool Heater

PROPANE : Hayward H400FDP

Natural Gas : Hayward H400FDNASME — Universal H-Series Pool Heater

PROPANE : Hayward H400FDPASME

Natural Gas : Pentair 460736 —  MasterTemp Pool Heater

*Note : All of these are 400,000 BTU pool heaters.

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Pentair 460805 | MasterTemp Pool Heater

400,000 BTU Pool Heater — Natural Gas

Available in 4 different models:

• Pentair 460736 MasterTemp – Natural Gas
• Pentair 460737 MasterTemp – Propane
• Pentair 460805 MasterTemp – HD (Heavy-Duty) – Natural Gas
• Pentair 460775 MasterTemp – ASME – Natural Gas

Features:

• 400,000 BTU Natural Gas Heater
• Cupro-nickel heat exchanger
• Heats up fast, so no long waits before enjoying your pool or spa
• Best-in-class energy efficiency*
• Manual gas shutoff when service is required
• Eco-friendly MasterTemp is certified for low NOx emission and outperforms industry standards
• Rotating digital display allows for easy viewing
• Tough, rustproof exterior handles the heat and weathers the elements
• Electronic Ignition
• Compact design : Provides you with more options for installation.

DOCUMENTS for the Pentair MasterTemp series:

• ✓ View or download the INSTALLATION & USER GUIDE
• ✓ View or download the Pentair Installation HEATER CHECKLIST
• ✓ View or download the BROCHURE.

Overview

If you need a heavy-duty heater for your swimming pool the Pentair 460805 MasterTemp won’t let you down. It’s rock solid externally and internally. The shell of the pool heater can handle extreme hot and cold conditions, plus it’s rustproof and will always look fantastic. It’s a huge positive because you don’t want it affecting the aesthetics of your garden.

On the inside, it’s got a few features to protect the heater including the popular cupronickel heat exchanger. A water pressure switch won’t let the unit overheat if there is a problem with your pool. If the water temperature exceeds factory setting limits it will automatically shut itself off. You’ll need to also keep an eye on the pool pH levels to extend the lifetime of the heat exchanger.

Diagram showing how Pentair MasterTemp Pool Heaters work

A 400,000 BTU pool heater will obviously heat your pool very quickly, but there are another couple of features you’ll love. I’m sure you care about how much the unit will cost to run every month. Natural gas isn’t too expensive to begin with, but the Pentair 460805 MasterTemp is extremely efficient too. Also, it’s perfect for the environment because NOx emissions outperform industry standards.

If any work needs to be performed on the 460805 MasterTemp you can switch the gas off manually. It’s got an easy-to-read LCD digital display that rotates around to help you see it wherever you are. The advanced diagnostics will tell you when something is wrong, plus it will tell you exactly what the problem is. In other words, it’s easy to use even if you don’t have much experience with gas-powered pool heaters.

Learn more about MasterTemp pool heaters by visiting the Pentair site.

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VIDEO | Behind the Scenes — Working at Hayward

Working at Hayward

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Hayward H400FDN | Universal H-Series

400,000 BTU Pool Heater — Natural Gas

✓  Also available in propane : Hayward H400FDP (400,000 propane model)

Features:

• Standard cupro-nickel heat exchanger
• Excellent salt water and chemical corrosion resistance
• Exclusive “Totally Managed” cupro nickel heat exchanger water flow
• Same water velocity through all tubes for faster heating
• Patented header by-pass design
• Up to 18 percent savings by reducing pump run-time
• 2″ x 2 1/2″ CPVC union plumbing connections
• Common union for installation or service, adapts to larger plumbing recommended for greater
• efficiencies
• Low NOx emissions – meets clean air quality standards

✓ View or download the MANUAL and the BROCHURE for the Hayward H400FDN.

Overview

If you’ve looked into pool equipment in the past it’s likely you’ve come across Hayward products. Not only are they one of the biggest companies in the industry, but they’ve also been going strong for over 80 years. The cutting edge technology has changed dramatically since their inception, but their main aim is still to provide you with the best equipment on the market.

You’ll find a cupronickel state-of-the-art Finn plate heat exchanger inside the Hayward H400FDN Universal H-Series pool heater. It’s durable and lasts for a long time, which includes surviving in less than ideal conditions. Think salt-based water, high flow pools, and any with aggressive water chemistry conditions. It’s guaranteed to last the distance.

VIDEO | Why Invest in A Pool Heater?

What are the differences between pool heaters?

Open up a 400000 BTU pool heater and you’ll see it’s not just the heat exchanger you should be worried about. There are other components that need to last a long time as well. For example, you’ll want the silicon nitride hot surface igniters, insulated combustion chambers, and stainless steel burners to be durable. The Hayward H400FDN Universal H-Series pool heater ticks all these boxes and more.

When you purchase a 400000 BTU pool heater you expect your swimming pool to heat up quicker than ever before. The powerful hydraulic performance of the H400FDN will reduce circulation time. Warm water will be pumped into your pool faster than usual. It’s only 83 percent energy efficient, but it’s pretty high compared to cheaper models and will save you money.

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TRANE TR400NA : Discontinued

400,000 BTU Pool Heater — Natural Gas

✓  Also available in propane : TRANE TR400LP (400,000 BTU propane model)

Features:

• Durable cupro-nickel heat exchanger
• Excellent hydraulic efficiency saves energy
• Low NOx emissions meet all air quality emission standards
• Easy retrofit installation
• Patented polymer header design provides superior hydraulic performance to save energy and protect against the damaging effects of erosion from high flow conditions
• Intuitive and easy to read L.E.D. Control Panel provides digital temperature readout, diagnostics and electronic ‘lock-out’ of temperature set-point

✓ View or download the BROCHURE for Trane pool heaters.

Overview

The LED digital control panel on the TRANE TR400NA 400000 BTU pool heater stands out. It’s got most of the usual things you would expect in a world-class unit. It will give you a temperature reading at all times, you’ll be able to lock in a certain temperature to make your life easier, plus it has built-in diagnostics. It’s also accurate, which is what you should expect when spending this much money.

All TRANE units have been built with cupro-nickel heat exchangers, so they’re definitely the best in the business. The reason they’re so coveted boils down to three main things. The cost of the heaters won’t break the bank, so every unit is affordable to the average person. They will also keep going for years and years if you treat them with care. On top of that, superb energy efficiency makes them legendary.

If you want a TRANE 400000 BTU pool heater they’re simple to retrofit. You won’t be able to do it yourself, but it will take a professional a few hours. The exterior shell is built to last in extreme weather conditions, plus it’s more attractive than your average pool heater too. It will look good in your garden if you manage to see it. The dimensions of the TR400NA are only 36.5 x 29.5 x 24 inches.

We’re going to delve into the specifics of how pool heaters work later in the article, but let’s just say cold water enters and warm water flows out. A pool heater needs hydraulics to help you achieve this while maintaining exceptional energy efficiency. The system on the TRANE TR400NA uses a patented polymer header design to save energy while protecting the unit from problems like high flow conditions.

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Hayward H400FDNASME | Universal H-Series

400,000 BTU Pool Heater — Natural Gas : Commercial ASME

Features:

• Patented Cupro Nickel Finn Plate heat exchanger with bronze header as standard
• Independent left or right side electric, water and gas connections
• 2in x 2 1/2in CPVC flanged connections
• ASME pressure relief valve included as standard
• Electronic lock-out feature prevents unauthorized access to configuration settings
• Easy installation and service via access of single front panel
• Easy gas valve adjustment
• Easy dual voltage conversion with fuse-protected circuit boards
• Texas Heater Kits Available
• 3 Years Parts and Labor

Overview

Look at the model number on this 400000 BTU pool heater and you’ll see an ASME label attached at the end. It stands for ‘American Society of Material Engineers’ in case you were wondering. The Hayward H400FDNASME takes advantage of a ASME pressure relief valve to ensure system safety. It’s the best choice if you plan on using your swimming pool all the time.

The ASME heater was actually developed to be used in commercial pools, which will be kept running non-stop during opening times. Luckily, they’re ideal for residential pools too, even if you don’t plan on swimming for an entire day. This model has a low-lead bronze header with a patented bypass design, which will use up to 18 percent less energy than conventional units.

Everyone who purchases a Hayward H400FDNASME Universal H-Series pool heater will live in different areas around the country. The weather conditions will never be identical in two places, but it won’t affect the 400000 BTU pool heater. It’s thanks to the forced draft combustion system. Air will move through the combustion chamber at a precise flow rate, which will eliminate external conditions.

Do you worry about keeping an expensive piece of equipment in your garden? You have to remember this Universal H-Series pool heater weighs 160 pounds, so nobody will be able to pick it up and carry it away. Gas heaters will have pipes attached making it even harder to steal. Nobody will even be able to mess around with the temperature. The lock-out feature will stop them in their tracks.

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Pentair 460736 | MasterTemp

400,000 BTU Pool Heater — Natural Gas

✓  Also available in propane : Pentair 460737 (Propane Model)

Features:

• Heats up fast, so no long waits before enjoying your pool or spa
• Best-in-class energy efficiency
• Hot surface ignition (no pilot light)
• Manual gas shutoff when service is required
• Eco-friendly MasterTemp is certified for low NOx emission and outperforms industry standards
• Rotating digital display allows for easy viewing
• Tough, rustproof exterior handles the heat and weathers the elements

Overview

One of the big features we’ve not looked at yet is noise. If you’re trying to swim multiple laps you don’t want any loud distractions in the background. Once you’ve switched the Pentair 460736 MasterTemp pool heater on you won’t even hear it unless you’re standing up close. The super-quiet operation ensures you can relax when you’re inside the swimming pool while staying toasty at the same time.

If you have any natural gas products in your home you’ll be aware of pilot lights, but they’re not very reliable. I’m sure you’ve pressed igniter buttons more than a couple of times in the past. The 460736 MasterTemp uses hot surface ignition to start everything up with the help of an electrical button. Once the surface is finally warm low voltage, high current electricity will ignite it.

The Pentair 460736 MasterTemp 400000 BTU pool heater measures in at 29.9 x 36.1 x 22.8 inches, so you won’t always be able to see it. A couple of features will help you out in this department. First of all, it can be elevated off the ground so it’s always in view. The user-friendly indicator lights will also let you monitor it without paying too much attention to it. You’ll know something is wrong when they flash.

It’s easy to say a pool heater has low NOx emissions, but it’s not just about buyers feeling good about helping the environment. There are low NOx regions around the country where emissions have to be under a certain amount. California is the standout state with the strictest rules. Don’t worry because you’ll be able to use your 460736 MasterTemp 4000000 BTU pool heater anywhere.ho

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How A Gas Pool Heater Works

In a minute, we’re going to discuss why you’ll need a 400000 BTU pool heater. It’s probably a good idea to talk about how they work before moving onto anything more complicated. A pump will circulate the water around your swimming pool, which includes sending it through a filter to clean it effectively.

The water will then move into the heater. While the water is moving through the system your natural gas will be burning in the combustion engine of the heater. It will generate a lot of heat and warm any water passing through it. By the time it reaches your pool it will be sitting at a higher temperature than before.

Imagine cold water flowing down a hill in a straight line trying to reach a puddle at the bottom. If someone was standing with a blowtorch blasting the water as it flowed downhill the puddle would be warmer than the water at the top of the hill. It’s essentially the same thing except pool heaters are much more technologically-advanced.

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Benefits of A 400,000 BTU Pool Heater

Those will a large pool will never regret buying a 400000 BTU pool heater. We’re going to discuss their main benefits, but first have a look at the table below, created by professionals. It shows what size of heater you’ll need depending on the water in your swimming pool and its total surface area.

Pool Heater Size / Gallons In Pool / Surface Area

• 100-200 BTU / 1,000-10,000 / Up to 300 sq ft
• 200-300 BTU / 10,000-20,000 / Up to 500 sq ft
• 300-400 BTU / 20,000-40,000 / Up to 800 sq ft
• 400 BTU / 40,000-80,000 / Up to 1200 sq ft

When you’re working out the size of your pool it’s always better to focus on the gallons of water inside it. The surface area can be a big help too, but it obviously doesn’t account for the depth of the water. If your swimming pool is a little deeper at one end it could add thousands of gallons onto the total.

Did you know there are 7.5 gallons of water in a cubic foot? Remember this number because it’s extremely important. If you want to work out how many gallons are in a constant depth (square or rectangular) pool you would use this equation:

Length x Width x Depth x 7.5 = Total Gallons

If you have a shallow end it’s also possible to use this equation to give you a rough estimate:

Length x Width x Average Depth x 7.5 = Total Gallons

Don’t worry if you have a more complicated pool. There are online calculators that will help you figure out the amount of water in your pool. This website http://www.swimmingpool.com/testing-water/pool-volume-calculator should give you all the information you need.

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Calculations Don’t Give You The Full Picture

A lot of people won’t have a swimming pool with more than 40,000 gallons of water inside it, so they might decide a 400000 BTU pool heater is too big. There are other things you’ll need to take into consideration too. They’ll offer you benefits a smaller pool heater could never give you even if your pool isn’t huge. Let’s take a quick look at them:

• Your Pool Will Heat Up A Lot Faster
• Minimal Price Difference
• More Energy Efficient
• Perfect For Heating Hot Tubs

Your Pool Will Heat Up A Lot Faster – The average gas heater will increase the temperature of a pool by a few degrees per hour. Obviously a 400000 BTU pool heater will work faster than a smaller one, which is good when you’re desperate to jump into the water.

Your swimming pool might have fewer gallons of water inside it, but you’ll wait a long time for it to heat up. If you’re ever on the fence about which model to buy always opt for a bigger one. It’s a decision you will never live to regret.

Minimal Price Difference – Have you looked at the price of pool heaters? Forget about the total cost because they’re worth it. I want you to examine the price difference between 400000 BTU pool heaters and smaller models.

You’re looking at a difference of roughly a few hundred dollars, which isn’t bad considering they’re worth thousands. Why would you try to save a little money when you could buy something a lot better without a noticeable difference in price?

More Energy Efficient – Gas heaters are excellent because you can decide on a temperature you like. The heater will do everything possible to keep it at your desired temperature every time you jump into the swimming pool.

Which model do you think will find this easier? A smaller model will have to work a lot harder than a 400000 BTU pool heater to maintain your preferred temperature. It means it will need to work harder, so it will burn through more energy over its lifetime.

Perfect For Heating Hot Tubs – I hope you have a hot tub attached to your swimming pool. Doing multiple laps to stay healthy is nice, but nothing beats relaxing in a tub. The only way you’ll enjoy them is when they’re nice and warm.

If you have a hot tub you’ll want a pool heater that will heat your tub up quickly and effortlessly. A 400000 BTU heater should warn your hot tub in around 15 minutes. If you own a smaller pool heater it will take longer until it hits your desired temperature.

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Getting The Most Out Of Your Gas Pool Heater

Once you’ve decided to spend a chunk of change on a gas pool heater you’ll want a couple of things. First of all, you’ll want it to last a very long time. If you don’t use it a lot you’ll get your wish. You’ll also want it to be more energy efficient, because you’ll spend a lot less money during the summer months.

It’s possible to accomplish these things by reducing the demands on your pool heater. A lot of swimming pool owners don’t even take them into consideration, but you can’t afford to ignore them. We’re going to look at the tricks you can use and why it will help you save lots of cash going forwards:

• Using A Good Pool Cover To Retain Heat
• Build A Fence To Stop Wind Getting In
• Use A Manual Thermostat To Test The Water
• Switch The Heater Off When You’re Done
• The Heater Installation And Maintenance

Using A Good Pool Cover To Retain Heat

A swimming pool is similar to the human body. It loses roughly 90 percent of its energy through the top of the pool. They say around 70 percent of heat is lost through evaporation, plus 20 percent is lost to the sky through radiation. The remaining 10 percent is lost through things like losing heat to the ground.

Think about that for a couple of minutes. It will add a huge amount of money onto your monthly bills, but the solution couldn’t be easier. All you need to do is put a cover over the top of your swimming pool when it’s not in use. Hopefully you’ll realize the time you will waste doing this is well worth it.

The pool cover you use doesn’t need to be anything special. There are bubble covers designed with thick grade materials and UV inhibitors, but to be honest any cover will do when you’re getting started. You can research all your options once you plug the hole in the bottom of your mug.

I’d like to give you a few examples of the costs it takes to heat a swimming pool per year when you try to do everything without (and with) a cover:

• New York $1448 ($208 with cover)
• Boston $1712 ($232 with cover)
• Los Angeles $1864 ($168 with cover)
• Seattle $1525 ($304 with cover)

Please Note: These figures are based on a pool heated to 78 degrees Fahrenheit. The swimming pool is 1,000 square-foot, uncovered 8 hours per day, and the gas heater is 80 percent efficient.

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*** Extra Pool Cover Benefits

At the moment, you must think pool covers are the greatest thing that’s ever been invented. They might not come close to the wheel, airplanes, or peanut butter, but they do have extra benefits too. I’d like to take a quick second to look at them to ensure you don’t go to bed tonight without ordering one.

You’ll Be Able To Conserve More Water – It’s not just heat that disappears into the atmosphere. 30-50 percent of the water from your pool will eventually disappear too, so you’ll need to keep topping it up on a constant basis. The world is running out of fresh water and they think it will cause mass devastation by 2050. Keeping a cover on your pool will help the planet.

You Can Start Using Less Chemicals – The chemicals you have in your pool will float into the sky too, which won’t be doing it any favors. It’s only going to speed up the destruction of our atmosphere. Using 35-60 percent extra chemicals will affect you negatively too. Not only will you need to pay for them, but you’ll need to store them in your garage.

It Won’t Take You Long To Clean The Pool – How long do you spend cleaning your pool on a weekly basis? Once you start using a pool cover those hours will drop considerably. If the leaves and other debris can’t fall inside they won’t need to be fished out. If you value your time it’s a fantastic investment.

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Build A Fence To Stop Wind Getting In

When you switch on the heater you’re not just trying to warm up a pool of water. You’ll be fighting against the elements at the same time. Cold winds will be doing their best to reduce the temperature of your water, which will increase the demands of your 400000 BTU pool heater.

In these situations, it’s tough but you’re not left completely helpless. You can begin battling against the wind. Don’t put too much effort into it because it’s not worth it. Just erect fences around your pool if you feel it’s too exposed. Do the work yourself and it won’t cost a lot of money.

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Use A Manual Thermostat To Test The Water

The reason we’ve mentioned 78 degrees Fahrenheit is because it’s the temperature lots of people set their pool heater too. It’s what the majority of the population deem comfortable. 82 degrees Fahrenheit is usually the maximum temperature they’ll set it to. There are no rules, it’s really up to what you prefer but these are a few general guidelines.

You can set your pool heater to any temperature you desire. The easiest way to do it is by dipping a manual thermostat inside your pool. If you decide it feels comfortable you don’t need to add a few degrees to the temperature. Turn the heater up if you feel too cold. You shouldn’t have to swim around to warm up. It should be relaxing the moment you jump inside unless you enjoy living on the edge.

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Switch The Heater Off When You’re Done

It’s pointless keeping your 400000 BTU pool heater switched on when you’re not using the pool, especially when you take into account how fast it works. This will save you a lot of money in the long run. Cover your pool and it won’t take too long to warm it back up. Just keep one thing in mind before you turn off the heater.

It should only be turned off if you’re not going to use the swimming pool for an extended period of time. You might like to do 100 laps of the pool before lunch to keep your heart strong. Maybe your kids will want to play in the pool later in the day when they get home from school. In these situations, you can keep it switched on.

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Heater Installation and Maintenance

Don’t get any funny ideas about installing a pool heater on your own. This includes carrying out any maintenance work on it. When a pool heater is installed and maintained by a professional it will improve its efficiency. You might have to pay money in the short term, but you’ll make it back in the long term. Unless something goes wrong you should call someone to have a look at it every 12 months.

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Why A 400,000 BTU Pool Heater Will Save You Money

We’ve looked at lots of modern 400000 BTU pool heaters today, but I’m sure a lot of people with swimming pools already have a heater. It’s clear you’re thinking about buying one, but like most people you could be sitting on the fence. The easiest way to change your mind is by showing you how old models waste tons of money because they’re so inefficient.

Let’s begin by looking at something really simple. I know 99 percent of people will already understand how heaters work, but it’s still good to see it written down. It makes you realize how much money you’re actually wasting. You have an imaginary pool heater sitting in your hands (which means you’re strong because they’re really heavy).

It’s 100 percent efficient, so for every $100 dollars you spend on gas you don’t waste a penny. This is a dream scenario everyone wants to see. Now imagine you’ve got a 65 percent efficient heater in your hands. For every $100 you spend, $35 dollars will be vanishing into thin air. You’re essentially throwing money away.

Most 400000 BTU pool heaters we’ve looked at today are around 95 percent efficient (100 percent heaters don’t actually exist). Let’s compare how much these models will save you compared to old ones. You’ll be able to do the math in your head to see if they’re worth it:

Heater Efficiency / 95% Efficiency / Annual Savings

• 55% / $580 / $420
• 60% / $630 / $370
• 65% / $685 / $315
• 70% / $735 / $265
• 75% / $790 / $210
• 80% / $840 / $160

Please Note: These savings are based on every $1,000 you spend each year. It’s easy to see a brand new 400,000 BTU pool heater will pay for itself if your current one isn’t efficient enough.

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Now Is The Time To Invest In A New Pool Heater

You should invest in a 400,000 BTU pool heater before you waste even more money. At least you know how much you’ll save on an annual basis. Don’t forget they come with a lot of other special benefits too, which should make your life a lot easier going forwards.

The only difficult choice you’ll have is deciding which one to buy. There is a cheat lots of people use on a daily basis. Click on the links and read the reviews past customers have left on Amazon. After you’ve consumed a few it will help you come to a final decision.

Read our indepth article on Inground Pool Heaters.