best pool heater for Inground pool

What Is The Best Pool Heater For Inground pool?

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Hayward W3HP21404T is the best inground pool heater. Cause at the end of the month, this heat pump can enormously save your pocket without compromising extreme heating capability. Also, it’s unbeatable for the ultra-quiet operation.

The heat-consuming rate of an inground pool is slightly different. So compactable pool heaters need to fulfill some additional requirements. Otherways, the swimming or spa session might be a nightmare.

Your inground pool time won’t remain enjoyable at all if you miscalculate the heating requirements. I will guide you entirely to measure the pool size, minimum necessary BTU, and required water flow rate to gift you a charmful pool event.

What is The Overall Best Pool Heater for Inground Pool? – Hayward HeatPro

Hayward W3HP21404T inground pool heater

Hayward is one of the most prestigious HVAC industries, and HeatPro is their most energy-efficient, popular, and flagship heating solution. We have already explained how efficiently the heat pump raises the water temperature and, Hayward has optimized the power at an artistic level.

It’s preferable for about 500-600 sqft large pools.

Heat pumps are quiet by nature. But Harward has turned the HeatPro into an ultra-quiet machine by integrating their patented acoustic compressor cover and profiled fan blades. Also, these elements boost power efficiency significantly.

Hayward uses R410A as a refrigerant, which is the most environmentally friendly solution. Additionally, they use Titanium Heat Exchanger for the evaporator unit to transfer heat most efficiently and keep the unit durable, long-lasting, and rust-free.

HeatPro has a massive 140K BTU capacity to handle a large inground pool. You may also pick a low-capacity variant of 90K or 125K BTU if required. But I will prefer the big one cause it can raise the water temperature faster, not impacting the electric bill. Why? Let me explain.

This pool water heater has a built-in electronically controlled thermostat unit that will hold the water temperature at one point. Once the temperature gets reached to your desired level, the compressor will automatically get turned off.

So the low BTU unit will drive the compressor for a long time than the high BTU variant. As a result, lower BTU won’t impact your electric bill that much.

Let’s talk about electric efficiency. This gigantic 140K HeatPro unit consumes 7.2KW of load, which is almost 3X lower than a family-size instant water heater’s watt consumption. It was only possible by the astonishing heating elements and NEW generation compressor.

An average quality inground pool water heater gets affected by rust, salty water, and chemical corrosion. As a result, they become fragile within a few months of use, which is nothing but a waste of money.

On the other hand, Hayward has used Ultra Gold corrosion-resistant fins in evaporator and injection-molded, UV-resistant body panels that are incredibly impervious to rust and deterioration.

The whole internal components are made of stainless steel, and evaporator coils are protected by a polyethylene screen that enhances endurance and immediately increases peak efficiency.

Best Propane Inground Pool Heater – Hayward H400

Hayward H400FDN inground pool heater

Hayward Universal H Series is a monster in the world of inground pool heaters. They are available in a wide range of 150K BTU to 400K BTU variants. You can pick them for both commercial inground pools and noncommercial household uses.

The excessive heating capacity raises your pool water temperature faster than anything else. Hayward has used a cupro-nickel heat exchanger inside the combustion unit that protects the heater from corrosion and failure for imbalanced water chemistry.

The dashboard with a bright LCD panel is extremely user-friendly that you can operate it with a few touches. An electronically controlled unit maintains the water temperature and holds it to your comfort zone. 

It’s an environmentally friendly unit that emits a meager amount of NOx. No other gas pool water heater offers 83% power efficiency like the Hayward H series.

Hayward has their Patented polymer header design that provides superior hydraulic performance cuts the electric bill by lowering pressure on the circulating pump.

You will find them both on Propane and Natural Gas Varients.

Here is a short BTU vs. Pool size comparison chart to help you find the suitable size for your inground swimming pool.

Heater CapacityPool Size
400K BTU/hr1400+ sq ft
350K BTU/hr1200+ sq ft
300K BTU/hr900+ sq ft
250K BTU/hr750+ sq ft
200K BTU/hr600+ sq ft
150K BTU/hr450+ sq ft
210K BTU/hr630+ sq ft

How to Identify Propane vs. Natural Gas Hayward Model?

Many people get confused about it, but here is the simple trick to identify them precisely. 

The natural gas model number ends with  FDN.

And the Propane variant’s model number ends with FDP.

That’s it!!!.

Difference between W3H400FDN and H400FDN?

Nothing but the Color!!! The models starting with the model number W3 are a bit lighter. Almost light brown or near to off-white. But the model number begins with H- is colored dark brown.

Does it matter? Of Course Not!!!

Best Budget Inground Pool Heater – Ecosmart 27KW

EcoSmart SMART POOL 27 Electric Pool Heater

If you require an instant, effortless pool water heater installation, then the EchoSmart On-Demand Inground Pool heater is unbeatable. You need to connect the heating unit with the water inlet and outlet and connect it with the power socket.

It works on the same mechanism as your household electric tankless water heater.

It consumes massive 27KW electricity, so the operation cost is expensive. We measured it, and that was almost $4.56 per hour. But the positive side is the unit price is very cheap.

Instead of a typical water pressure valve, the EchoSmart has used an advanced flow sensor to increase longevity. Also, the heating elements are sturdy and covered by stainless steel tubes. So undoubtedly, you will enjoy the trouble-free warm spa session for long years.

EchoSmart on-demand pool heater can raise water temperature almost 1-1.5 degrees F per hour and is suitable for up to 18,000 gallons of water holder pool.

To run this unit smoothly, you need 240V electric outlet and one 100 Amp circuit breaker or 50 Amp Double Breaker.

The company provides an extended 2-years of warranty, which is fantastic.

Best Natural Gas Inground Pool Heater – Raypack

Raypak 014952 336000 BTU Pool heater for inground pool

Raypack is another industry-leading brand for manufacturing gas inground pool water heaters. This gas water heater is entirely digitally controlled and more futuristic than any other unit.

They are available in a wide BTU range of 180K to 300K. Additionally, you will find both the PROPANE and NATURAL GAS variants. Both of them are great performers and cost-efficient.

What did they haven’t done to enhance durability and performance and smush all other competitors? Their body materials are polyester coated and made of a non-corrosive cabinet. The whole unite has to pass 7 layers of tempering system, including electrode metal polishing and galvanizing.

So the infrastructure will remain sturdy in any terrible climate like rain, storm, imbalance water chemistry, and everything else.

According to temperature, a smart microprocessor maintains the water flow rate inside the combustion chamber to keep the temperature of the heat exchanger above 105 degrees F.

This unit is comparatively easier to install and to beat the competition, the price tag is lower than others on the field. But the performance is relatively far more satisfying.

Cupro Nickel heat exchanger protects the unit from salt damages. The heating efficiency of Raypak is undoubtedly top-notch.

You can pick Raypak instead of Hayward to save a couple of hundred bugs, and they both are almost the same. Even, electronically Raypak is better and more intelligent.

Cheapest Heat Pump for Inground Pool- FibroPool FH055

FibroPool FH055 In Ground Swimming Pool Heater

Can you think about heating your 10,000 Gallon water holder inground pool with only ~25 cents operational cost? FibroPool FH055 has made it possible. Not only that, this heat pump does the job in the very fastest way.

FibroPool has a slim and convenient design and is highly optimized for energy efficiency.  Additionally, the enamel-coated steel chassis ensures decades of rust-free operation.

The heat exchanger unit is corrosion protected and galvanized stainless steel build body material ensures a reliable shield against imbalanced water chemistry, minerals, acid rains, and other natural destroyers.

This unit has a digital control panel with an LCD, but I’m not that much a fan of it. Controlling features seems a bit tricky, and the dashboard isn’t too fancy.

Otherways this heat pump is a great pool water heater, and you will enjoy using it insanely. But there is a bit issue. If the climate remains too cold, the heater may take a bit longer hours to warm your pool.

You must require a 240V outlet to install it.

In case you require a smaller-sized unit, you may read my brought guide to find some above ground pool heater here.

What Size of Inground Pool Heater will be suitable for me?

It’s one of the essential facts, but many people do misunderstand this. 

Heating and Cooling capacity is calculated by “British Thermal Unit” (BTU), and water flow rate through the heater is measured by “Gallon Per Minuit” or GPM.

We need to find both these units’ sweet spot to install the perfect inground swimming pool heater at our home. Otherways, either the water temperature won’t get raised at our satisfaction level, or the heater will be overpowered and start burning electric bills.

Explanation of BTU:  The amount of heat is required to raise 1 pound of water temperature by 1 degree Fahrenheit is called 1 BTU. 

So one swimming pool heater is 140,000 BTU/hr; it explains that this heater can raise 140,000 pounds of water temperature by 1 degree Fahrenheit within 1 hour.

Oh, weight, you may think 140,000 pounds!!! That’s are huge!!! Why do I need that!!! 

Oh man, wait…

Firstly, environmental air will blow a ton of BTU every second. The ground layer will absorb some. Mechanical components will destroy some BTUs at the time of generation. So you might get the rest, and the amount is not more than 80%-83%, depending on the efficiency.

Let’s calculate the required BTU of your Inground pool water.

Weight of 1 Cubic Foot water = 8.3453 pounds.  

Say your pool is 20 feet long and 15 feet wide. The average depth of the pool is 5 feet. Then the volume will be 20x15x5 = 1500 cubic feet.

Weight of 1500 Cubic foot water will be 1500×8.3433 = 12,514.95 Pounds.

That means a 12,514.95 BTU/hr capacity heater will raise the pool water temperature by 1 degree Fahrenheit within 1 hour.

If the environment temperature is 50 degrees F, the heater will raise the water temperature to 86 degrees F by 36 long hours. 

Unfortunately, you will never want to wait that long, and within that 36 hours, air will blow out at least 20 degrees of Farenheight.

So if you install a 55,000 BTU/hr producer pool water heater, that will raise the temperature 4X faster. The more the BTU, the faster you will able to enjoy a charming swimming session.

Essential Knowledge about Best Pool Heater for Inground Pool

Types of Heaters That Are Available For Inground Pools

Energy isn’t destroyable, and it can be transformed from one form to another form. Almost all of us know this eighth-grade equation.

The water heater works on the same foundation. So there are several ways to raise water temperature. Using electricity, gas, sunlight, and so on.  

Based on fuel type, there are mainly 4-categories of pool water heaters. They are

  1. Heat Pump Type Pool Heater
  2. Gas Driven Pool Heater
  3. Electric On Demand Pool Heater
  4. Solar Pool Heater 

Let me explain their whole mechanism so that you can decide which one is suitable for your inground pool.

Things You Should Know About Heat Pump Inground Pool Water Heater  

Heat pump isn’t new to the world. It was invented in the 18th century, and still, now that is the most efficient way of heating or cooling both air and water. 

All air conditions work on this mechanism, and a giant pool water temperature can be raised using a heat pump. Even, this is the most energy-efficient way of increasing the water temperature.

A heat pump can absorb the environmental temperature and releases it into the water to warm it and vice versa.

4-Main components are the main elements of a heat pump. 

A. Compressor

B. Refrigerant

C. Evaporator Unit

D. Condenser Unit

Freon gas is being used as the refrigerant, specifically R410A, which is a particular freon format. Some different companies use different forms, like R22, R12 but R410A is the most environmentally friendly solution.

The whole amount of refrigerant remains sealed inside the compressor. Unless any leakage of the capillary tube, you have nothing to do with it.

First, the compressor compresses the refrigerant; then it gets turned into a liquid form. At the same time, the refrigerant becomes very hot and passes through the CONDENSER unit.

Inside the condenser, there are many titanium tubes, which are called a heat exchanger. The hot refrigerant passes through these heat exchanger tubes, and water flows surrounding it. As a result, the water starts getting hot.

Through this procedure, the refrigerant loses some heat and move towards the evaporator unit. 

Inside the evaporator, the refrigerant starts decompressing. As a result, it gets chilled. Again the chilled gas passes through a heat exchanger tube, and a Fan blows air surrounding it so that the gas can releases the chilled temp to the environment and absorb some heat.

Again the refrigerant return to the compressor. That’s how the heat pump absorbs environmental temperature and releases it into the pool water.

Now, you may ask why this is the most efficient way of raising water temperature? 

In a traditional water heater, an electric current passes through a high resistive nichrome wire, and the wire becomes hot. But most of the electric energy remains unused because of wire resistance, and day by day, the performance efficiency decreases.

But the heat pump can transform up to 83% energy, and in the long term, nothing happens to the machine. Even if any refrigerant leakage occurs, that is repairable, which is a very low-cost fact. As a result, heat-pump offers both low operation cost and maintenance requirements.

We have researched that if you use a heat pump at your pool at the end of the month, it will save at least your $350+ electric bills, which will be a massive amount at the end of the year. 

Who doesn’t like saving money in the long run? So if you have the ability, the heat pump should be your first preference.

Gas Driven Pool Water Heater- When are they Essential?  

This pool heater category is widely available in the United States, Canada, and the UK and popular for larger pool useability.

While an electric pool heater’s highest power ends at around 140K BTU/hr, the gas pool heater variant starts from 100K BTU/hr and reaches up to 400K BTU/hr.  So if your inground pool size is excessively large, you would have no different options except a gas pool heater. 

Several popular electric pool heater brands do manufacture gas pool heaters too. For example, Hayward and Pentair are the most popular among them.

Gas pool heaters contain 4-different main elements, and they are

  1. Blower
  2. Electric Ignitor
  3. Combustion Chamber
  4. Heat Exchanger

How does the gas pool heater works? 

Firstly the blower sucks environmental air and gas from the gas outlet. Inside blowers, gas and air are being mixed and compressed. Then the blower nozzle forcefully passes the compressed air inside the combustion chamber.

An electric ignitor set a fire inside the combustion chamber, and the flame starts discharging like an afterburner jet engine. The combustion chamber starts getting hot excessively.

The heat exchangers are nothing but high heat tolerable metallic tube wrapped by sharp metallic fins. They exist surrounding the combustion chamber and absorbs heat from it. At the same time, water flows through the tube and starts getting hot.

Thus the pool water remains circulating through the gas heater and starts raising the temperature.

Is the gas pool water heater Dangerous? Any chance of Blasting?

Gas pool heaters are 100% safe, and there is almost 0 possibility of dangerous things occurring.

Only the issue that happens with these heaters after a very long time of use is mostly water leakage. Which is very easily identifiable, and any local plumber can fix it within a while. 

Why Natural Gas Heater and Propane Heaters Are Difference?

Natural gas is mainly Methene (CH4) and a mixture of several higher alkenes, while propane is C3H6.

Propane contains three different carbon molecules, and methene contains only one. As a result, burning propane produces 3X more energy than methane. 

As a result, if you need 1 liter of propane to raise your pool temperature by 1 degree, you will require around 3 liters of natural gas to do this. 

So the propane gas heater’s internal blower will suck a low amount of gas from the outlet comparing the natural gas. That’s why propane heaters and natural gas heaters are slightly different.

Note: Propane is expensive than natural gas, but natural gas can produce a low amount of heat comparing propane. So operation cost of the propane heater and the natural heater is balanced. You should choose them according to the availability in your area.

Does gas heaters environmentally friendly? 

It’s a difficult question, and I should answer diplomatically. Burning fossil fuels means doing a little harm to the environment. The electricity we are using is also a result of burning fuels. We haven’t any different choice. So we should repair the environment in different ways.

On-Demand Electric Inground Pool Heater 

This shorts of pool heater is very similar to your household tankless electric water heater. 

The advantage of this kind of inground pool heater is the low price tag, easy installation. With a similar capacity of heat pump’s price, you can buy at least 5 On-Demand Electric pool heaters.

 Again the disadvantage is, the operation cost is at least 3X more than a heat pump. So, in the long run, the heat pump users will win the deal.

Inside the On-demand pool water heater, you will find a heating element, which is a high resistive nichrome wire. Some brands protect the nichrome wire with an additional rustproof metallic tube.

Whole heating elements remain wrapped by sharp fins, and water flows through them. As a result, the water absorbs temperature from the heating coil and starts getting hot.

When should I Choose On Demand Electric Inground pool Heaters?

If you require an instant heating solution but don’t want to spend too much on a heat pump, then you may go for it.

Or if you’re living in warmer places like coastal areas, you might also prefer this for short time uses during the day. Cause you won’t require to count huge electric bills through the whole year.

Caution of On-Demand Electric pool heater: Never forget this thing, if your pool water is salty like the sea, don’t use this type of heater even in an unconscious mind. Cause saltwater is an electricity conductor. 

If your pool water is a bit salty that you can’t taste with your tung, then it’s okay to use.

Solar Inground Pool Heater: If your place remains sunny enough the season wide you may prefer installing a solar pool heater.

As it is very cheap in price, you may install it additionally with a heat pump or gas-driven pool heater. 

Cause in windy and cloudy weather, it won’t work. Even this device is a useless installation for the winter season.

The solar pool heater has an extension to install on the rooftop or open space where sunlight has effortless access. This extension has several black rubber tubes to flow water through it. Black objects are excellent heat absorber, quickly sucks heat from the sunlight and transmits to the flowing water.

Generally, it can raise the pool water temperature to 5-10 degrees in very sunny weather. 

Does the solar pool water heater really useful?

You may think that we walk under sunlight, it hasn’t that sufficient temperature to make the whole pool water hot. Man, don’t underestimate this!!!

If you place a metallic object and a wooden object under the sunlight, after a while, you even can’t touch the metallic parts. Cause it can transmit heat, and the wooden thing is heat resistant. 

Similar way, the air is heat resistant, so it doesn’t transmit the heat. So we don’t feel it in the environment. But the solar tubes can absorb the entire heat from sunlight and make the water hot.

But the weather never remains clean every day. So if you install a solar pool heater, additionally, that would be a great solution cause it’s entirely free for your entire life.

At the end of the season, it will save you thousands of bugs for sure.

On-Demand Electric vs. Heat Pump, which one is the best?

Of course, the heat pump. An on-demand electric heater shouldn’t even compare with a heat pump at all. But the on-demand pool heater is excessively cheap comparing to the heat pump.

The heat pump is far more energy-efficient. Again the heat pump can raise the water far faster than an on-demand pool heater.

On the other hand, an on-demand electric heater consumes electricity at an extreme level. So at the end of the month, your electric bill will be skyrocketing.

So unless your budget is too low, you should only go for a heat pump.

Multiple pool heat pump or single Gas heater- Which setup is preferred? 

This question is very interesting. A gas heater is more powerful and less expensive than a heat pump. But the heat pump has an extreme level of electricity efficiency.

We did some research and asked a ton of pool users. Both the gas heater and heat pump are too reliable and long-lasting. Again a 400K BTU/hr gas heater’s price is less than a 140 BTU/hr heat pump.

But the operation cost of a heat pump is very much low. So if you want to use the pool commercially and require a very long operation, it’s better to install multiple heat-pump.

Investing in multiple heat pumps will save a lot of money and hassle for you. 

But for household uses, if your pool is excessively large, you may prefer the gas-driven inground pool water heater. 


Nobody buys an inground pool water heater too frequently. If you invest in a great unit that will serve you for decades.  So the quality and capacity are uncompromisable cause it’s going to be a long time bound with this pool heater.