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Review | Pentair 460805 MasterTemp — 400,000 BTU Pool Heater

Pentair 460805 : best 400,000 btu pool heater
Heats up your pool quickly and efficiently. (Buy from Amazon)

Review of the Pentair 460805 MasterTemp — A high-quality natural gas 400,000 BTU Pool Heater.

Before you dive straight in and buy a pool heater, I’d recommend that you give this article a thorough read. Not only will we be reviewing the Pentair 460805 MasterTemp natural gas pool heater, but we’ll also be looking at two other comparable models – the TRANE TR400NA and the Hayward H400FDN Universal H-Series.

These are all 400,000 BTU natural gas pool heaters and provide the most effective heating for large pools and spas. We’ll be covering a lot in this article, it’s not simply a review of some the best natural gas pool heaters. Before you make your decision, there will be a lot of questions that you probably want answered. What size pool heater do you need? Which is the best pool heater for your needs and budget? How does a pool heater work? Can you save on your pool heating costs?

Yes, we’ll be answering all these questions and a whole lot more. I’ll provide an easy way to calculate the size pool heater that you’ll need. I’ll also be comparing the major types of pool heaters available: Natural gas; solar and heat pumps. You’ll get to know the pros and cons of the various types of pool heaters and be able to make an informed decision as to which pool heater will work for you. There’s a lot to consider. It’s not just about the size of your pool and what temperature you want it to remain at. Your geographical region plays a large part and this is not just about how hot or cold it is where you live. The availability of fuel or sunlight varies according to where you live. So you’re going to get the information that you need.

We’ll go into all these topics in detail after reviewing the pool heaters that we’ve selected. Though before I begin, I want to clarify why we’ll only be looking at natural gas pool heaters in this review. Basically, natural gas pool heaters provide the most effective heating – they heat the water faster than any other method. In cold northern climates, natural gas is the preferred method for heating a pool. This is not only because of their highly effective heating but in the north, natural gas is more readily available and often works out as the most economical option. Though you should check the price of natural gas in your area before making a cost-based decision. If you don’t have piped gas in your area, it’s going to mean installing large propane tanks. This could cost a bit, not only to buy the tanks but also because propane can be expensive in some areas. I’ll go into more detail about this when we discuss the different types of pool heaters.

There’s a lot to cover, so I’ll begin by reviewing the natural gas pool heaters that we’ve selected. As always, we’ve done our research so you don’t have to waste your time. All three of these of these pool heaters have been carefully selected for their reputation as being high-quality items. After doing a thorough check of which natural gas pool heaters are the favorites amongst homeowners, these models came up tops. They’re all fairly similar in price and a pool heater of this size and quality isn’t exactly what I’d call cheap. Though these three aren’t the most expensive that you’ll find. The aim here is to help you invest your money wisely. If you’re going to be paying a few thousand dollars for a pool heater, you want something that’s going to last and you don’t want to waste your money on exorbitant running costs and maintenance.  The Pentair MasterTemp and its two counterparts, provide a healthy balance. They’re reasonably priced when compared to other high-end pool heaters and provide a level of quality, reliability, and durability that’s hard to beat.

A Quick Overview of 400,000 BTU pool heaters (Natural Gas & Propane) :

Pentair 460805 | MasterTemp Pool Heater

400,000 BTU Pool Heater — Natural Gas

Pentair MasterTemp 400 Pool Heater review.
A reputation for efficiency, reliability and value.

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Available in 4 different models:

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:

Overview

If environmental issues are high on your list of priorities, the Pentair MasterTemp 460805 should be your first choice when looking at natural gas pool heaters. The debate surrounding pool heaters and the environment is a contentious one. A pool heater uses a lot of energy because you’re heating a very large volume of water and there’s a lot of heat loss because your pool is exposed to the elements. Naturally, no one can say that the Pentair 460805 MasterTemp beats solar when it comes to green pool heating. But solar is not always viable – not all areas have enough sunlight available to properly heat a pool. Comparing the Pentair MasterTemp to electric pool heaters depends very much on how the electricity is generated where you live.

Renewable electricity generation is environmentally friendly, but it can only provide some of our electricity needs. So electric power is never going to be completely clean energy. Natural gas is widely considered to be a green energy source and, for the most part, I agree with this. But natural gas is not without its toxic elements. NOx emissions from natural gas are harmful and the Pentair MasterTemp has the lowest possible emissions of this harmful gas – way better than industry standards. Not only is the Pentair MasterTemp one of the cleanest burning natural gas pool heaters, it’s also super-efficient so it uses less gas whilst heating your pool faster. It’s a win-win situation.

Diagram showing how Pentair MasterTemp Pool Heaters work

Pentair-MasterTemp-400-how-does-it-work

Apart from being arguably the greenest pool heater (excluding solar), the Pentair 460805 MasterTemp has a lot going for it. A 400,000 BTU pool heater can be a huge and noisy beast. The Pentair isn’t at all big, measuring 36” X 30” X 30”. It’s also virtually silent and is contained in an attractive and very durable sound-insulated housing. It won’t look out of place in your yard and will never disturb the peace and quiet of your poolside environment. I’m not sure about the heat exchange that’s used in the Pentair 460805 MasterTemp because on their website, they give efficiency stats for both a standard copper heat exchange and a Cupro Nickel one. So I think you have an option, it would be nice if the guys at Pentair could clarify this. Copper is slightly more efficient and Cupro Nickel is more durable. So there’s playoff here between energy efficiency which means lower fuel costs and long-term durability which reduces your maintenance cost.

The Pentair 460805 MasterTemp has easy to use controls with a touch pad under an enclosed flap at the top of the unit. Simple controls with an LED display make it quick and simple to manage the temperature of your pool and you have all the information you need at a glance. This keypad rotates, so it’s easy to use no matter where you stand in relation to the unit. It also provides diagnostics for troubleshooting and a host of safety features, including a manual gas shutoff for service. It’s easy to install with external pipe connectors at the side of the enclosure.

There can be no disputing that the Pentair 460805 MasterTemp is a high-quality item with a durable, weatherproof enclosure. It’s user-friendly and refreshingly quiet. Along with this, it’s very fuel efficient and environmentally friendly – earning it the Pentair Eco Select stamp of approval. This honor is reserved for products that have been specifically designed to reduce their environmental footprint in every conceivable way. While this can easily be considered the best natural gas 40,000 BTU pool heater, it’s not the most expensive. Beating many others both in features, performance, and price. This is a real winner in my book.

TRANE TR400NA

400,000 BTU Pool Heater — Natural Gas

best 400,000 btu pool heater
Very well-made and affordable.

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✓  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 Trane reputation for building excellent equipment is a solid one. For over a hundred years this has been a trusted name among homeowners and you can be assured of superior quality and outstanding performance. The Trane TR400NA has the same heating spec as the Pentair MasterTemp 460805, 400,000 BTU. So it’s a highly effective way of heating a large pool or spa.

While Trane specifies that the TR400NA meets all NOx emission standards, Pentair claims that the MasterTemp 46805 exceeds these standards. Granted, there’s no conclusive scientific information by which we can compare these claims without exact figures. Though I’m led to believe that the Pentair is probably the more environmentally friendly of the two. The Trane TR400NA is also a very compact unit with similar size specs to the equivalent Pentair model: 36.5” X 29.5” X 24”.

The enclosure that houses the pool heater is a durable unit and has a clean and modern look. It’s not going to be an eye-sore beside your pool. The hydraulic flow engineering that’s gone into designing this pool heater makes it highly efficient and the use of a Cupro Nickel heat exchange makes it one of the most durable. This heat exchange is considered to be heavy-duty and outlasts the standard copper components used in many others.

It has an easy to use touch control with an LED display that makes it really easy to keep your pool at the perfect temperature and run diagnostic checks. The pipe connection setup is similar to that of the Pentair MasterTemp with PVC inlet and outlet points at the side of the unit.

In my opinion, the Trane TR400NA is the best-looking pool heater of the bunch. Though aesthetics is a matter personal taste and not all will agree. In respect to quality design and build integrity, this pool heater compares favorably to the Pentair MasterTemp 46805. There’s no telling for sure, but a preliminary observation seems to suggest that the Pentair pool heater may be the more environmentally option when comparing the two.

Hayward H400FDN | Universal H-Series

400,000 BTU Pool Heater — Natural Gas

best 400,000 btu pool heater
Excellent performance makes this heater easy to recommend.

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✓  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

This 400,000 BTU pool heater matches the other two in most respects. The Hayward meets all NOx emission standards but they, too, don’t make the same claim as Pentair that it exceeds this standard. It is, none the less, an efficient and well-made pool heater.

It’s a compact unit, like the other two and is housed in a neat-looking weather-proof enclosure. The two connectors for water inlet and outlet are placed in the same way as the other two. They are situated side-by-side and on the exterior of the enclosure for easy installation. It’s corrosion-free and is perfectly suited to salt water pools. Although the other two manufacturers don’t say this on their websites, I would say that they are all suitable for salt water pools. They use similar components. The Hayward H400FDN also makes use of a durable Cupro Nickel heat exchange.

The touch controls with an LED display give you the same easy to use pool heating management system and it’s conveniently positioned at the top of the housing. On their website, Hayward state that this pool heater results in an 18% saving by reducing the pool pump runtime. I find this statement to be slightly ambiguous because they don’t say what they’re comparing it to. The figure looks like a comparison to electric heat pump pool heaters which aren’t as effective at heating the water. If this is the case, the same can be said for any of the natural gas pool heaters in this review.

When it comes down to it, all three of the natural gas pool heaters that we’ve reviewed here are very similar. They’re all quality items and it may be hard to choose between them. Unfortunately, I can’t help you with your decision, they all seem great to me. The Pentair MasterTemp appears to be the most environmentally friendly (though there’s no confirmation of this). For the rest, it may come down to price, in that one model may be noticeably cheaper at any given time. This would depend on special offers and the like. Otherwise, you may end up choosing the one that looks the best to you and will fit in better with the look of your patio. That’s if it’s going to be seen at all.

How does a pool heater work?

There are different methods used to heat the water in your pool, but the basic principles of a pool heater remain the same. So whether it’s an electric, natural gas, or solar pool heater, they’re going function in a very similar way.

A pool heater uses your pool’s circulation pump to circulate the water through a heat exchange. This is a series of pipes that pass over a heating unit which is usually electrically powered or uses a natural gas-fueled flame. Solar heat exchanges take the form of solar collector tubes, you’ve probably seen them on the rooves of some houses.

Electric and gas pool heaters use a thermostat to monitor and control the temperature of your pool. You’re able to program the pool heater to keep the pool at the exact temperature that you want. Many will also have programmable functions like time managed pool temperature. This means that you can set the temperature to be higher at certain times of the day or only on certain days of the week. This helps you conserve energy and save on your pool heating costs.

Solar pool heaters don’t offer the same flexibility when it comes to managing your pool’s temperature. These systems rely on sunlight and can, therefore, only heat your pool when the sun is shining. So you can’t always be sure how warm the water in your pool will be.

What size pool heater do you need?

Like the heaters we use in our homes and air conditioners, pool heater specs are given in BTU (British Thermal Unit). This is a standardized measurement indicating heat transfer. So basically put, it’s the amount of heating units that will be transferred into your pool’s water per hour. A higher BTU rating will heat the pool faster than a lower one. If your BTU rating is too low for the size of your pool, too little heat will be transferred. This will mean that the heat lost to the air won’t quite match the heat being transferred into the water. Your pool is going to cool down faster than the pool heater can replace the heat and you will never reach the desired temperature. Or perhaps, on colder days it won’t reach the desired temperature. This will depend on how your pool heater’s BTU capacity compares to the volume of your pool.

The quick solution would be to simply go for the biggest pool heater you can find – why leave it to chance? This would mean that you’re, quite literally, burning through your money. A large pool heater is going to cost more to buy and will use the most fuel/electricity. Obviously, a solar pool heater won’t use more fuel but a larger unit will cost more to install. With solar, you don’t have a BTU rating, the sun determines that. So when it comes to solar, it’s usually best to go as big as you can afford. Though you’ll usually be advised by the guys that install it. In certain areas, the sunlight is better than others.

When it comes to choosing the correct natural gas or electric pool heater, it’s best to know how many gallons of water your pool holds. You might not know how much this is, so I’ll also give you the formula to calculate your BTU requirement based on the length and width of your pool.

You first need to calculate your expected temperature difference. This would be the difference between the temperature that you want your pool to be and the average temperature of the coldest month during which you’ll be using the pool. This is a simple calculation, you’ll take your desired pool water temperature and subtract this from the average temperature for the chosen month and the answer gives you the temperature difference. Basically put, this is how much heat you’re expecting to add to the water. In other words, how many BTUs you’ll need. You can get the average monthly temperatures for your area on the US Climate Data website.

Here’s an example of how this calculation will work in practice:

If, for example, you live in Washington DC and you want your pool to remain at 80°F. You probably won’t be using your pool during the coldest months – who’s going to be swimming when the outside temperature is around 20-degrees? So let’s take a reasonable example of the average temperature in Washington DC during October. This is 67°F – I’ve used the average high temperature because the average low would be measured around 4 AM. So to get your expected temperature change your calculation would look like this: 80 – 65 = 15. Your temperature difference is 15°.

Here’s a list of the BTUs needed in relation to the number of gallons that you’ll be heating at various temperature differences.

For a temperature difference of 5°, you’ll need:               For a difference of 10°, you’ll need:

  • 175 BTU for pools 80-90 gallons                                            • 175 BTU for pools 40-45 gallons
  • 200 BTU for pools 90-110 gallons                                          • 200 BTU for pools 45-55 gallons
  • 250 BTU for pools 110-125 gallons                                        • 250 BTU for pools 55-65 gallons
  • 300 BTU for pools 125-165 gallons                                        • 300 BTU for pools 65-85 gallons
  • 400 BTU for pools up to 200 gallons                                      • 400 BTU for pools up to 100 gallons

For a difference of 15°, you’ll need:                                      For a difference of 20°, you’ll need:

  • 175 BTU for pools 25-30 gallons                                            • 175 BTU for pools 20-22 gallons
  • 200 BTU for pools 30-35 gallons                                            • 200 BTU for pools 22-26 gallons
  • 250 BTU for pools 35-45 gallons                                            • 250 BTU for pools 26-35 gallons
  • 300 BTU for pools 45-55 gallons                                            • 300 BTU for pools 35-45 gallons
  • 400 BTU for pools up to 65 gallons                                        • 400 BTU for pools up to 50 gallons

If you don’t know how many gallons of water you have in your pool, here’s how to calculate your BTU requirement based on the surface area of your pool. We estimated this on an average pool depth of 5-feet.

You’ll need to calculate your pool surface area by multiplying the length of your pool by its width. As an example, we’ll use a pool 20’ x 40’ – giving us a surface area of 800 square feet.

We now take our temperature difference (15°), multiply it by the pool’s surface area (800 SQ-FT) and multiply this by 12 to get the BTU requirement:

15 X 800 X 12 = 144,000 BTU, so a 145BTU pool heater will be sufficient to handle this requirement. You’ll choose the model closest the BTU requirement of your pool.  This is the minimum BTU requirement and may take a while to heat your pool, especially if you’re using a heat pump. For more rapid heating, you can always use pool heater with a slightly higher BTU rating.

Which type of pool heater is going to work the best for you?

Knowing how many BTUs you need to heat your pool is important. Though the type of pool heater that you choose is going to have the greatest effect in the long-run. It will affect your operating costs and the efficiency with which you heat your pool and this can be crucial.

There are three basic types of pool heaters to choose from: solar; natural gas and electric. When looking at electric pool heaters, a heat pump is the way to go. Old-fashioned resistance heaters are hardly used anymore because of the amount of electricity they use. So I’ll only be discussing heat pumps as the best electric pool heater option.

Solar Pool Heaters

I’m all for green energy and this makes solar a great option. Water is circulated from your pool to solar collectors that maximize the sun’s energy to heat the water. This seems to make perfect sense – once you’ve paid for the installation, you have free pool heating for life and there are virtually no maintenance costs.

However, solar is not without its drawbacks. It’s quite obvious that you can only heat your pool water when the sun is shining. This creates a bit of a paradox because it’s precisely when you have little to no sunshine that you most need to heat your pool. Despite this, solar pool heaters are very popular in areas that have a high average amount of daylight hours with low cloud cover. You can always heat your pool to a slightly higher temperature when sunlight is available to compensate for the times when there is less sunlight. Later when I discuss saving on pool heating costs, I’ll discuss pool covers. They offer a brilliant solution for reducing your heat loss when there’s no sunlight.

Another issue with solar pool heating is the amount of time that your pool pump has to run. In order to get the maximum benefit from a solar pool heater, your pump needs to circulate the water for as long as the sun shines. A solar pump can help because it, too, will only operate when the sun shines but this will further increase your installation cost which is already higher than all the other types of pool heaters.

When talking about the high installation cost of a solar heater, we need to think long-term. Solar collectors are likely to last a lifetime. So paying a bit extra in the beginning is going to pay for itself over time. There’s no exact way of determining your payback period for a solar pool heater. You first need to consider how much sunlight you get where you live and compare that to the cost of running natural gas or electricity every day. Whichever way you look it at it, solar is going to save you money, it’s just that the payback period will vary – depending on your individual circumstances.

Another problem some people have with a solar pool heater is that of the general aesthetics of your home. Solar collectors need as much direct sunlight as possible and this usually means putting them on the roof. While solar collectors on the roof aren’t too unsightly, you need to have pipes running up your walls to the roof and this can be a problem if sufficient care isn’t taken to do it neatly. If you use a longer pipe distance to hide the pipes, like running them to the side of your house far from the pool, you’ll lose a lot of heat over this extra distance. So this is something to consider.

If you don’t mind the fact that you may have to compromise slightly in that your pool’s heating is dependent on available sunlight, this is a great pool heating solution. Though you need to look at the availability of sunlight, I wouldn’t recommend a solar pool heater for very cold areas with low sunlight.

Natural Gas Pool Heaters

For uncompromised and highly effective pool heating, natural gas pool heaters are the best option. Natural gas can be expensive but this depends a lot on where you live. There are areas where electricity is more expensive to use than natural gas and vice versa. You’ll be able to determine which is the most cost-effective in the area where you live.

Regardless of the cost, natural gas heats the water much faster than any other method. This makes natural gas the best for cold climates where you may want to set the temperature lower for colder times and then want heat the pool rapidly when you want to use it. This can result in a small saving when it comes to the cost of running your pool pump. Because your water heats up more rapidly, you won’t need to run the pump for too long before your ideal temperature is reached.

Hayward H400FDNASME (Commercial ASME) | Universal H-Series

best 400,000 btu pool heater
Commercial quality components for exceptional durability. (Buy from Amazon)

If you don’t have piped gas where you live, gas might not be your best option. This would mean installing large propane tanks which cost extra and refilling propane tanks is usually more expensive than piped gas. In addition to this, propane tanks don’t look all that great and, unless you have you have somewhere to conceal these tanks close enough to your pool pump, your pool area can end up looking poor.

For the most part, natural gas is an excellent solution. As an environmentally sound way of heating your pool, it can be a hassle when it comes to NOx emissions – many areas have strict regulations around this. Though most of the better pool heater manufacturers are aware of this and produce very clean-burning natural gas pool heaters.

Electric Pool Heaters

Heat pumps have become very popular. They are way more efficient than resistance heaters and this means that the cost heating your pool using electricity is much more attractive. A heat pump isn’t as effective as natural gas. So it will take longer to heat your pool but, once your pool has reached the set temperature, the heat pump will maintain this without any difficulty. Provided that the heat pump has the BTU capacity to match the size of your pool.

As with using natural gas, the cost of using a heat pump will depend entirely on how much you pay for electricity in your area. Generally, heat pumps are more popular where electricity is cheaper than natural gas.

How to save on your pool heating costs

Using either natural gas or electricity to heat your pool is going cost you. These costs can become very steep and you’ll want to take any measure possible to avoid spending too much. Solar doesn’t have the same problem but you’ll want to retain as much heat as possible when you’re generating it. So some of these measures will apply to solar – not as a cost-saving measure, but as a heat saving one.

Install your pool heater as close to the pool pump and the pool as possible. Every foot of extra piping will result in a heat loss, reducing the efficiency of your pool heater.  It helps to insulate these pipes wherever possible.

Try to use your pool heater economically. If you’re not going to be using the pool for a while, it makes sense to switch the pool heater off. You could also set it to a lower temperature when the pool isn’t going to be used too often and crank it up before using the pool.

Probably the most effective way of saving on pool heating costs and very easy to do, is to use a pool cover blanket. When it comes to solar pool heaters, I’d consider this a must-have item because you’re not going to lose as much valuable heat. A solar crystal pool cover blanket is designed to collect and store heat, as well reduce the amount of heat escaping from your pool. A regular winter pool cover can help some, but these pool covers do a fantastic job and will save you heaps of cash.

If you cover your pool with a solar crystal pool cover blanket, it will not only reduce the heat loss, it will actually assist in heating your pool because the pool blanket collects and stores heat. Covering your pool with one of these blankest whenever it’s not in use takes a small amount of effort, but the rewards are too good to ignore.

Learn more by reading our comprehensive article on 400,00 BTU pool heaters.

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