
The Hayward HP21404T is the most popular size (140,000 BTU) heat pump from the HeatPro series so we are featuring it front and center but this article will cover all of the models in the HeatPro series so you can decide which model is the one you need.
We know it can be confusing when shopping for a pool heater so we work hard here to make the information as clear as possible so you can invest your money wisely.
Table of Contents...
β Hayward HeatPro Models

*All AHRI certified.
- Hayward HP21404T = 140,000 BTUΒ β Square
- Hayward HP21254T = 125,000 BTUΒ β Square
- Hayward HP21104T = 110,000 BTU β Round
- Hayward HP21104TC = 110,000 BTU (Low Ambient) β Round
- **Hayward HP21004T = 95,000 BTU β ?
**Note: Model HP21004T is shown as round on the Hayward site but in their brochure it is shown as a square model. So, to be honest, I have been unable to verify its shape. We will update this when we know for certain. Ultimately, you need to choose the model based on the BTU, not the shape but I just wanted to clarify this so you’re not surprised if you order this model.
But, before we focus on these models let’s discuss some important factors when deciding how to heat your swimming pool, such as the difference between pool heater vs heat pumps β there are significant advantages and disadvantages to each one.
Heating your Swimming Pool
What is the point of having a swimming pool in your garden if you only get to use it for a few months every year? It takes a lot of work to maintain your pool, so it’s vital you stretch out the length of time you’ll be able to use it on a yearly basis. Luckily for you, it’s much easier than you think.
All you need in order to extend your swimming season is warm water, which will require some sort of device to heat the pool up. This means depending on where you live you could possibly swim up to 365 days per year. Although it sounds good you might be worried about the costs involved, but there is a simple solution.
Video | Overview of Hayward HeatPro Heat Pump Series
Hayward HP21404T Features:
- 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
- 2″ x 2.5″ CPVC Union Plumbing Connections – Common union for installation or service, adapts t0 larger plumbing for greater installation flexibility.
- Lighter Weight – Less than 250 lbs.
β View or download the MANUAL and INSTALLATION GUIDE for the Hayward HP21404T, and all of the HeatPro Models.
Heat Pump vs Pool Heater
You have a couple of options when it comes to heating up your pool, but the two most popular ones today are the electric heat pump and gas pool heater. The latter has been around for a very long time and it’s the only reason why it’s still commonly seen in pools around the country. It’s quickly dying a death thanks to the heat pump for one huge reason.
Did you know heat pumps like the Hayward HP21404T cost roughly one third of the price a gas pool heater will cost you? It’s easy to argue about the higher initial cost, but at the end of the day when something will last over a decade you’ll save a bucket load of money. You’ll also become a much better swimmer because you will be able to use your pool twice as long.
β What Size Of Heat Pump Do You Need?
Think about what a heat pump actually does. Its main job is to make sure your swimming pool stays at the desired water temperature at all times. Any heating unit is constantly fighting a battle with the surface area of your pool, because it needs to top up the temperature of the water at the same time as heat is escaping into the air. I don’t want to confuse you too much with math, so let’s look at a simple equation.
Let’s say the total surface area of your swimming pool is 389 sq.ft, because you have a perfectly round pool 15 ft in diameter.
You want the water temperature to be around 77 degrees because that is the minimum it’s supposed to be in competitive races.
Finally, the ambient temperature is sitting at 50 degrees.
- Surface Area = 389 sq.ft.
- Desired Temp = 77 degrees
- Ambient Temp = 50 degrees
First of all, you would subtract the ambient temperature from the desired pool temperature and you’d be left with 27 degrees. Now you should follow this equation:
Temperature x Surface Area x 12 = 126,000 BTU
BTU stands for British Thermal Unit, and it’s the heat you need to raise one pound of water by one degree. Obviously you would be looking for a heat pump with a BTU rating higher than 126,000 if you had a swimming pool this size.
β What Makes Heat Pumps Different?
Today we’re going to be looking at one particular model in the Hayward HeatPro series, which is the HP21404T and it’s the undisputed king of the bunch. There are also more in the series, so let’s quickly look at the BTU of all the models:
- Hayward HP21404T = 140,000 BTU (AHRI) β Square
- Hayward HP21254T = 125,000 BTU (AHRI) β Square
- Hayward HP21104T = 110,000 BTU β Round
- Hayward HP21104TC = 110,000 BTU (Low Ambient) β Round
- Hayward HP21004T = 95,000 BTU β ?

Do you notice anything strange about those numbers? They’re actually a lot more identical than you think when you compare them to gas pool heaters. Can you imagine the BTU you would need if you doubled the diameter of the swimming pool we used in the equation earlier on? The BTU would be much higher than 140,000, so it’s easier to think of heat pumps like the HP21404T slightly differently.
β How Does An Electric Heat Pump Actually Work?
A heat pump doesn’t even generate any heat, which is one of the reasons why it’s so cheap to run. Once a unit like the Hayward HP21404T is set up a fan will begin to suck air in from the environment. It’s the reason why heat pumps are usually only suitable when the ambient temperature is around 60-65 degrees, although they can still work well when it’s slightly colder.
It essentially takes the heat from the air and combines it with the water in your swimming pool. As the water from the pool is pulled into the heat pump the hot air will circulate over an evaporator coil and the temperature of the water will begin to rise. This process is repeated over and over again until the pool is finally at your desired temperature.
Now we’re going to look at the two main reasons why you would want a heat pump with a higher BTU rating:
β Your Pool Will Heat Up Quicker
Electric heat pumps like the Hayward HP21404T are in no way as powerful as the biggest gas pool heaters. It’s going to take your pool days to heat up once everything is switched on, but it’s hard to give you an exact number of hours because it will depend on how many gallons of water your pool contains. Still, a heat pump with a 140,000 BTU rating is going to heat up a pool quicker than one with a 110,000 BTU rating. At least once it’s heated up the temperature will remain constant.
Video | Pool Heat Pump vs Heater
β It Will Use A Lot Less Energy
Even though your pool temperature will remain constant, it’s still going to be fighting against all the heat lost from the surface area. A smaller heat pump with a low BTU rating will also be battling against the ambient temperature on occasion. It will have to work for longer to keep the pool at your desired temperature, which means higher electric costs because of the decrease in efficiency. It’s for these two reasons a high BTU is always beneficial.
Why The Hayward HeatPro Series Is So Special?
Apple rules the world when it comes to smartphones. Microsoft rules the world when it comes to operating systems. Facebook rules the world when it comes to spying on your friends. Who do you think reigns supreme when it comes to swimming pools? Hayward has been going strong for over 80 years and during that time they’ve constantly been at the forefront of the industry when it comes to innovation.
You can see it clearly today because of their in-ground HeatPro heat pumps. The Hayward HP21404T is clearly their number one product, so we’re going to focus on this model when looking at all the special features. Luckily apart from the BTU rating all the models are almost identical, so we’ll cover the HP21404T now and touch on a few minor differences between them all at the end.
Hayward HP21404T HeatPro | 140,000 BTU

- The Heat Pump Is Almost Silent
- Designed For Maximum Heat Transfer
- Exclusive ‘Ultra Gold’ Evaporator Coil
- Able To Handle The Harshest Conditions
- Great Digital LED Control Panel
- It Doesn’t Take Up A Lot Of Space
- The Unit Is AHRI Certified
β View or download the BROCHURE for all Hayward HeatPro heat pumps.
β The Heat Pump Is Almost Silent
You would expect a heat pump like the HP21404T to be loud as it’s sucking in so much air, but you can only hear the fan when you’re standing close to it. The main reasons for this are of course the profiled fan blade and acoustic compressor cover.
It’s obviously not completely silent, which nobody would expect anyway because of what it does. On the plus side, you’ll need to keep the unit well away from the pool so you won’t be able to hear anything when you’re lounging around.
β Designed For Maximum Heat Transfer
The BTU rating on a heat pump doesn’t really mean anything if the unit isn’t efficient. It’s also going to be annoying if one small design flaw lets you down, but the engineers at Hayward have ensured that won’t happen by using a titanium heat exchanger.
It’s going to make sure every last bit of heat finds its way into the water, and it will also help when the ambient temperature isn’t so high outside. The titanium heat exchanger also won’t suffer from any corrosion due to chemicals or salt water.
β Exclusive ‘Ultra Gold’ Evaporator Coil
Earlier on we spoke about the heat pumps costing more money upfront, but it’s not only the way it works that saves you lots of money going forwards. It’s also the way it is built, which includes all the special features you won’t find in other heat pumps.
The HeatPro series uses an exclusive ‘Ultra Gold’ evaporator coil, which is designed to last a very long time. It’s especially helpful when your fan is pulling in air from coastal areas, because some heat pumps just couldn’t handle the salty air for years.
β Able To Handle The Harshest Conditions
Everything we’ve talked about in regards to durability has focused on the interior of the HP21404T, but don’t be fooled into thinking the exterior of the unit won’t be able to handle the terrible weather conditions. The injection molded panels are tough.
The panels on the unit won’t be able to rust or deteriorate over the years. They are even UV-resistant to prevent them from fading in the sun. It’s also going to handle the cold well if it’s winterized, which is essential if you live in a state with freezing winters.
β Great Digital LED Control Panel
The temperature of your pool will ultimately be decided by how hot it is outside, but when it’s not too cold you’ll be in full control. That is because you’ll be able to change the temperature using the easy-to-read digital LED control panel on the front of the Hayward HP21404T.
Your digital control panel also has an extra treat in store, because it will be able to tell you exactly what is wrong with the heat pump. Even though it’s not going to run into problems on a regular basis, its self-diagnosis capabilities will save you lots of time and money.
β It Doesn’t Take Up A Lot Of Space
Don’t be scared by the weight of the heat pump. It might be a massive 250 pounds, but you’ll never have to move it once it’s in position. You should be more concerned about the actual dimensions, which are 40 x 43 x 32 inches making it really small.
If it sounds too good to be true it’s because it probably is. The dimensions might not seem like much, but the heat pump will need clearance room due to how it works. It must have at least 24 inches of space around the unit and 72 inches of space above it.
β The Unit Is AHRI Certified
Before we ever mentioned the HP21404T we spoke about the company itself. Hayward has been around for longer than any other company in the industry and they only provide you with the best products available. They’ve still went out to get their heat pumps AHRI certified.
This simply means it’s been independently tested inside a laboratory by experts who have made sure the claims made are all true. They are certified so you know they’re telling the truth. Go out and see how many companies you can find willing to do the same thing.
β The Rest Of The Hayward HeatPro Series
Hayward HP21104T | 110,000 BTU

All of the other models in the Hayward HeatPro series are almost identical to the Hayward HP21404T model . The only real difference is the weight and dimensions, but they don’t count for anything at the end of the day. The only real thing you need to worry about is the BTU rating, so let’s take another look at the smaller models and you can remind yourself how powerful they are:
- Hayward HP21254T = 125,000 BTU (AHRI) β Square
- Hayward HP21104T = 110,000 BTU β Round
- *Hayward HP21104TC = 110,000 BTU (Low Ambient) β Round
- Hayward HP21004T = 95,000 BTU β ?
*Please Note: I’m sure you’ve noticed ‘Low Ambient‘ is written in brackets next to the Hayward HP21104TC model. This is actually a rather big difference. It means the heat pump will be able to work in colder temperatures, for example, it will work well when the ambient temperature is 50 degrees as opposed to 60 degrees.
Hayward HP21254T HeatPro | 125,000 BTU

Hayward HeatPro Heat Pump Is Easy To Install
If you don’t know anything about plumbing and electrics you’ll hire someone to install the heat pump for you. Why on earth would you try to do something yourself with such an expensive piece of equipment when you don’t have a clue what to do? Unfortunately the problem lies with those who know a little about installing appliances, because in order to save money they might be tempted to do everything themselves.
Why you should hire a professional?
- Location Of Your Heat Pump
- Amount Of Clearance You Need
- Flow Rate Of The Water
- Minimum Overload Protection
- Local Electrical Codes And Regulations
Please read the installation guide to understand the complexity of installing the HeatPro heat pump. Don’t try to install it yourself. Hire a professional β unless you are an actual pool technician. This will be repeated many times in this article because it’s important.
β Location Of Your Heat Pump
The location of your heat pump is very important, but would you have any idea where to put it? If it doesn’t get the maximum amount of sunlight possible it’s not going to work as effectively. Not only does it need to be in a place where it can take in air, but that specific place shouldn’t be where the air recirculates.
What about installing the heat pump and suddenly realizing you’ve not left enough room to get into the access panels? Also, if you install the Hayward HP21404T in an enclosed space it’s not just going to ruin the performance and destroy your property. You can also say goodbye to the warranty.
Amount Of Clearance You Need
There aren’t a lot of places you can put the heat pump while still making sure you have the clearance space you need on all sides, which we already said was 24 inches with no exceptions. The 72 inches of clearance above the unit might be hard if you have an overhanging roof.
We’ve not even touched on the fact your HP21404T must be a certain distance away from the edge of your pool. It’s 60 inches minimum in America, but if you’re installing the heat pump in Canada that distance automatically doubles.
β Flow Rate Of The Water
We haven’t even looked at anything directly related to swimming pools yet. Do you know the minimum and maximum water flow rate of your pool? You’ll need to know when installing the heat pump because it’s designed for a minimum water flow rate of 30 and a max of 75.
If you want to prevent damage to the heat exchanger you can add an external bypass assembly to regulate the flow rate. This isn’t just an option if the flow rate is 75 gallons per minute or higher. Without an external bypass assembly it will void your warranty.
β Minimum Overload Protection
It’s easy to replace a fuse in a plug when it’s broken. All you have to do is open it up and put it back together again, but that doesn’t mean you know anything about electrics. At this moment in time you probably won’t have a 50 amp circuit breaker.
If you tried to hook your Hayward HP21404T heat pump up without first installing a 50 amp circuit breaker you’d be in all sorts of trouble. It’s the minimum overload protection required on this specific heat pump and missing those kind of little things could mean big trouble.
β Local Electrical Codes And Regulations
You could argue the plumbing connections are easy to deal with yourself, but it’s impossible to argue with the fact you’re not a qualified electrician. You do actually have to follow codes and regulations, which involves knowing what they are in the first place.
Following the instructions in the Hayward HP21404T Manual andΒ Installation Guide is going to help, but only an electrician will already know the basics. Don’t forget electricity can kill you. Hopefully those points have convinced you to go down the professional route.
Please Note: A qualified electrician must deal with the wiring even if you’re insistent on doing the plumbing yourself.
Hayward HP21104TC HeatPro | Low Ambient

The Hayward HP21104TCΒ is ideal ideal if you live in an area where it gets cold, like Buffalo, USA.
Warranty | Hayward HP21404T
….and other models in the Hayward HeatPro series.
When you receive your warranty you’ll notice it talks about a couple of things, so it’s not as straightforward as one you might usually get. Here are the main things you’ll receive:
- 2 year warranty for parts
- 1 year warranty for labor
- 5 year limited warranty for compressor component
- 10 year warranty for titanium tube component
You’ll need to remember things like these too:
- Improper pool chemistry won’t void your warranty
- Installing the heat pump without following Hayward specifications will void your warranty
Please Note: Most of the parts inside the Hayward HP21404T are built to last a very long time. There will still come a day when you’ll need to repair something and spare parts are easy to pick up. If anyone other than a person authorized by Hayward touches your heat pump it will automatically void your warranty.
Tricks And Tips | Hayward HP21404T HeatPro
Once you’ve bought your heat pump you can read through the instruction manual yourself, but I thought it would be a good idea to share a few things you might like to know now. It will help you when deciding if you want to purchase the product, because you’ll know the extra jobs you’ll need to take care of once it’s up and running:
- You’ll Need To Use A Pool Cover
- The Chemistry Of Your Pool Is Important
- Check The Heat Pump On A Regular Basis
- Putting It Into Hibernation Over Winter
You’ll Need To Use A Pool Cover
This is perhaps the most annoying because it involves the most work. Are you used to covering your pool at night right now? Don’t forget losing heat from the surface area of your pool is what will cost you the most money. Thankfully you don’t have to do it every night in the middle of summer, but if the nighttime temperature is going to be 15 degrees lower than you want your pool to be the cover will need to go on.
The Chemistry Of Your Pool Is Important
You know the chemistry of your pool won’t void your warranty because we’ve just mentioned it, but it doesn’t mean it’s not still very important. The life of your heat pump depends on it, and because it’s not cheap you want it to last as long as possible. Unless you know how to do it yourself it’s good practice to have your pool chemistry checked often by someone who knows what they’re doing.
Check The Heat Pump On A Regular Basis
If your pool is at the ideal temperature you might not check the control panel on a regular basis. This is even more likely to happen because the Hayward HP21404T won’t be near the pool. Failure to check it means you might not see any warning codes until it’s too late. It’s always better to fix something before the problem gets even worse, so checking the unit is one extra job you’ll need to do.
Putting It Into Hibernation Over Winter
When you live somewhere chilly you’ll need to cover up your heat pump. It might be strong enough to withstand the elements, but ice can kill it from the inside. Every year you’ll need to take the time to trip the breaker. The In and Out water connections then need to be disconnected so you can blow all the water out with air. Once you’ve connected them back up again the unit should be covered to protect it from snow.
The Ultimate Way To Enjoy Your Swimming Pool
Do you remember how many months you were able to use your swimming pool last year before it was too cold to step inside? If you’re a big fan of relaxing in the pool it won’t have been long enough no matter how many months you used it for. The Hayward HP21404T will be able to change your life forever. Maybe you won’t be able to use the pool all year long, but you’ll still appreciate an extra few months.
Realistically, unless you live somewhere chilly it’s going to be a lot longer. Once you’re ready to come to a final decision there is always one smart thing you can do. Visit Amazon and read all the unbiased reviews previous customers have left for you. It’s especially helpful when you have your eye on this particular heat pump because everyone seems to love it.
Visit the Hayward site to learn more about HeatPro heat pumps and their extensive pool product line.