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Comprehensive Guide to Hot Tub Pumps

Here’s Everything You Need To Know

When your hot tub pump functions properly, it is easy to take it for granted. No component is more important for your hot tub than the pump. If you don’t have a functional pump, then you just have gallons of water sitting in between your hot tub walls. A functional pump uses pressure to circulate the water in the hot tub and keep it moving for the sake of heating and filtering it.

If you suddenly notice screeching noises or weird sounds when you turn on your hot tub one day, then some problems might exist with it. Perhaps your jets are not shooting out any water, and your water remains stagnant. This is the worst possible situation your spa could be in.

As a hot tub owner, you must learn how to recognize these troublesome signs and overcome any problems which might exist. If you can learn how to operate and care for your hot tub pump properly, then you’ll never be in a situation where your tub has a lot of swampy green water in it.

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About Hot Tub Pumps

When your hot tub pump malfunctions, you shouldn’t try to repair or replace it immediately. Learn about the specifications of your spa first. The side of the pump should have a label on it with technical information regarding speeds, horsepower, size, and discharge type.

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Single Speed vs. Variable Speed

The pump provides the necessary power needed for hot tub water to circulate and for the jets to operate. Low speeds and high speeds are needed for the pump. Revolutions per minute, or RPM, is the unit of measurement for these speeds. If you have one pump that can alternate from low speed to high speed and vice versa, then you have a variable-speed pump. It is also called a two-speed pump in some cases.

Whenever your spa uses a single-speed pump, there are actually two of them present. The first single-speed pump is the circulation pump. It requires less energy than most pumps, but it operates much slower too. This pump can move anywhere from 25 to 35 GPM (gallons per minute).

You could take the smallest variable-speed pump, and it will still have a speed of at least 100 GPM. The largest and strongest variable-speed pump may have up to 260 GPM in speed.

When you have a second pump present in the hot tub, it is always faster than the first pump because it is responsible for giving power to the jets. The second pump can be a variable-speed pump or single-speed pump. Whenever you already have a circulation pump in your spa, you can take certain two-speed pump models and reconfigure them to run at a single speed.

Wet End and Dry End

All pumps have wet ends and dry ends. The purpose of these ends is to prevent water from getting into the motor area of the pump. Water would destroy the components of a motor if it made contact with them.

An impeller is positioned at the wet end of the pump. This is what moves the water and allows it to circulate through the system. As for the dry end, the motor is housed there in a sealed area where moisture and water cannot get through. Of course, the dry end has components which can stop working just like the wet end does.

To give you an example, let’s say residue builds up in your impeller and causes it to get stuck. This can greatly impact the water flow of your hot tub. In another example, the electrical wiring of your motor may have a short in it. This will randomly trip the breaker.

If there is a problem with a single component, each end can be repaired separately in some cases. However, the cheapest option is usually for the damaged pump to be replaced completely.

Voltage

Electricity is needed to power the motor of a hot tub pump. You must find out if your pump needs between 220 and 240 volts or between 110 and 120 volts. When there are two wires supplying electricity to the pump, then it needs between 110 and 120 volts. The colors of these wires are usually white and green.

If four wires are connected to the pump, then it requires between 220 and 240 volts. The colors of these wires will be red, black, white, and green. Look at the side label of the pump, and you should find the voltage listed in that location.

As the hot tub pump is replaced, make sure you keep the previous power cord that was used on the older pump. You can use this power cord on the new pump just the same. Another power cord will probably come with your next pump, but you can always have a spare power cord in case something happens to the one you’re using.

Horsepower

The amount of power that your pump provides is referred to as horsepower (HP). Your spa pump can have anywhere between 0.75 HP to 5 HP.

But even if your pump has 5 HP, you can’t take advantage of that power unless you have the right plumbing. For instance, if you have a lot of small pipes, then they won’t be able to handle a lot of power going through them. This will cause your power to be limited, which will result in leaks.

Pumps usually have a bloated HP rating anyway. You’ll see this often with pumps which have “SPL” on the label. This signifies a special rating exists that is inflated. When the horsepower of the pump is different in the factory than in the spa, this process is known as an uprating.

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Discharge

Water comes out of a certain area of the pump that is called the discharge orientation. You’ll find this location on the side of the pump or on top of it. This comes in handy if you need to adjust the water level of your spa.

There are certain brands of pumps which don’t discharge with universal fittings. If you purchase a new pump with no universal fittings, then the unions must be replaced after the pump is installed.

Size of the Frame

Your pump is surrounded by housing that has holes already drilled into it. You can use these holes to bolt the housing to the interior of the hot tub. The frame size determines how far apart the holes are from each other. If you don’t have the right frame size, then it will be impossible to bolt it in there.

Your spa pump will either have a 56 frame or 48 frame. There should be a sticker on your pump which has either a 56 or 48 printed on it to indicate the type of frame it is. If you don’t see a sticker like this, just conduct your own measurement of the space between the bolts. These will either be the bolts on the motor or the frame. Bolts that are under 4 inches apart from each other signify a 48 frame. If they are over 4 inches apart, then you have a 56 frame.

Prime the Hot Tub Pump

If there is an empty hot tub and water is added to it, the circulation system will get air stuck in it. But the air can get pushed out of the system if you prime the pump. This will ensure that your water circulation is corrected in the spa. Make sure you prime the pump prior to your first use of the spa and right after you refill the spa with new water. It’ll also need priming in some cases in between.

You may have a self-priming pump, but that doesn’t mean it will work completely on its own. Every pump model requires a unique priming method, so check for the details about that in your manual. 

Here are the two main methods of priming:

1) Control Panel
If the control panel of your pump has a priming mode option, then priming the pump will be as easy as pushing a few buttons. 

Just activate your jets at low speed for up to 20 seconds. Then switch their speed to high for up to 20 seconds. Keep repeating this cycle until you see normal water pressure. You shouldn’t see any air bubbles or hear any gurgling while the jets are on. 

2) Manual
If you were unsuccessful in using the control panel method, try utilizing the bleeder valve of the pump to discharge the air.

Turn off the circuit breaker so that your pump won’t shock you with any electricity in it. Go to your pump and look on the discharge side of it. The gate valve should be closed here. 

Now the bleeder valve should be turned slowly until the sound of air can be heard hissing out of it. Wait for the sound to go away, then turn the bleeder valve in the opposite direction to tighten it up again. Make sure it is tight or else a water leak may occur there. 

Turn on the circuit breaker and hot tub. See if the jets are working. 

Additional Priming Recommendations

If you tried priming your pump, but you still face problems, then here are some other things you can try:

  • Clean your filter thoroughly. See if there are additional water flow problems like leaks or clogging.
  • Make sure the water level of the hot tub is where it should be. A low water level indicates a water flow problem.
  • One priming failure shouldn’t make you give up. Keep trying both priming methods until the pump is primed properly.
  • If you don’t know whether the pump has water in it, then don’t prime the pump for over 2 minutes. Otherwise, the pump might get damaged.

Pump Troubleshooting

If you have bad things happening to your pump, then here are a couple of things that you can try to fix the problems. 

1) Your Pump Does Not Prime
The sounds of bubbling and gurgling mean that air is trapped in your jets. You’ll usually hear these sounds after your spa is filled with water. If these sounds are not heard, then your filtration system probably has debris clogging it up. Air cannot escape the filter if it is clogged. 

Clean out your filter and leaf trap to fix that issue. Prime the pump now and see if it works. If it does not work, then keep activating and deactivating your jets to squeeze out the rest of the air in them. 

Make sure the heat is turned down first. Then you can completely open the jets and let them run on high for up to 15 seconds. Do this for 3 more times but increase the time of each one by 15 seconds as you go through them. Air bubbles will come from the jets. Once you stop seeing the bubbling, you can turn off the jets. 

2) Little to No Water Pressure
If you notice the water circulation of your hot tub is poor or stagnant, then it could be due to three possible reasons. You might have low water pressure, air that cannot escape, or the inability to prime your pump. Fortunately, you can solve these problems by checking your circulation system for any physical debris or complications. 

The first step is to clear out the debris from your leaf traps and filter. If the water pressure is poor, then you should drain all the water from the hot tub. Remove the debris from your circulation system with a line flush product. Then clean everywhere in the hot tub. Keep the jets completely opened prior to the cleaning process. 

If you perform a deep clean, use a hot tub cover, replace the used water with fresh water, and perform regular maintenance on your hot tub, then you can prevent most water pressure problems from occurring. However, if there are no physical elements diminishing your water pressure, then you must inspect your pump to find the reason.

3) Motor Randomly Shuts Off
If your motor randomly loses power, then it means it’s almost dead. Try resetting the circuit breaker to fix the issue. If that doesn’t work, then either the motor is bad, or the wiring is bad. 

You can check the wiring and its ability to deliver a regular flow of motor power by using a multimeter. Only do this if you know what you’re doing. If the test determines that the wires are not delivering electricity properly to the motor, then either replace the wiring or clean the wiring if there is corrosion present. Corroded wires often mean there are leaks, so look for them too. 

If the issue is coming from inside the motor, then your motor must be replaced completely. 

4) Motor Turns On, But Water Does Not Circulate
If you have no water circulation even when the motor is running, then your circulation system may be clogged, or your impeller is stuck. If you hear grinding sounds, then it means your impeller is not moving the way it should. There are probably electrical issues or some kind of residue impeding the rotation of the impeller. 

Clear out the debris from your leaf traps and filter. The GFCI should be flipped to stop electricity from going to the pump. Inspect the impeller now. If there is debris causing problems in it, then remove the debris and test the pump.

Sometimes your impeller might be damaged too. In that case, it must be replaced. If that doesn’t solve the problem, then replace the motor entirely because it is irreparable. 

5) Pump Does Not Turn On
If the pump doesn’t activate, then your spa is not useable. Check to see if your control panel works. If it doesn’t, then your spa has no power going to it. 

Resetting the breaker may help. Here is how to do that:

  • Find where your breaker box is located. It should be near your spa somewhere. Look for a metal box on your home or on a post.
  • Once you find it, open the box and see if the breaker to the tub has already tripped or not. If it has, then other problems might exist in your hot tub.
  • Flip the breaker off for a few seconds and then flip it back on.
  • Activate the pump and see if this flips the breaker. If it does flip, then your pump must be disconnected, and the breaker must be reset. If the breaker doesn’t trip unless you connect the pump, then your pump is the problem. If the breaker does trip, then the problem is not your pump. 

At this point, call a professional to have them inspect the electrical components of the hot tub.

6) Water Leaking
You’ll never want water close to your GFCI or within the spa cabinet. If water gets into these places, then you must have a leak. If you don’t do something about this leak, your pump will stop working properly. It could also cause your motor to get fried, corrosion or rust on your electrical components and your breaker to get tripped.

You probably won’t notice the slow leak inside your cabinet until it gets more serious. You should occasionally watch out for moisture near the pump seal areas. This is a sign of a leak in the cabinet. Use a flashlight to see better in the cracks and darker areas of the spa, such as the impeller housing. If freezing temperatures existed outside, then cracks will most likely form.

After you repair the leak, make sure your electrical components were not damaged by the leaky water. Clean the corrosion from the wiring or replace it entirely if it’s in bad shape. 

In some cases, your pump won’t be repairable. You’ll need to replace the entire thing if that happens. Just make sure you choose the proper pump replacement so that it is compatible with your hot tub.

How Do I Choose the Right Size Pump?

You can find the size and other specifications on the sticker of your current pump. If they’re not there, then you can figure them out yourself.

  • The distance between the bolts is the frame size. Take this measurement. Anything under 4 inches means it is a 48 frame. Anything over 4 inches means it is a 56 frame.
  • The required GPM for your jets can be determined by counting the number of jets in your hot tub and multiplying it by the flow rating. The manufacturer of your spa can also share those details with you. 

 With a variable-speed pump, the circulation and jet intensity can be adjusted. Two varying amperages will appear on its sticker. 

In cases where there are two pumps, then you probably have a single-speed pump. 

  •  Voltage: A power supply with two wires means the pump is between 110 and 120 volts. Four wires mean it is between 220 and 240 volts.
  • Horsepower – Keep the horsepower near the same horsepower as the original pump. It should not be over 1 horsepower more than the original.
  • Size of the Plumbing – The diameter of your pump’s PVC pipes should be measured as they relate to the intake and discharge of the pump. Then you’ll know the proper size unions to use. 

New Spa Pump Installation

If you must replace your pump with a new one, then the installation process is simple enough. Just make sure you purchase the proper replacement pump.

Remember to flip the breaker prior to starting or else you could get shocked.

  1. Drain the water from the hot tub or close the valves. You don’t want the water to come out when you uninstall the pump.
  2. Have a Shop-Vac or a couple of towels handy. Water will flow from the pipes.
  3. Remove the copper grounding wire.
  4. The discharge fittings and intake fittings must be loosened.
  5. Take the bolts out of the frame.
  6. Move the pump very slowly to access the wires. Detach the wires.
  7. Connect the wires to the new pump correctly.
  8. Replace the O-rings or unions if you need too. Now tighten the fittings.
  9. Securely bolt the frame in its position.
  10. Add water to the spa. Try out the pump.

Conclusion

Every hot tub needs a functional pump. If you properly care for the pump, then it should last for a long time.

Continue removing debris from the leaf basket and hot tub. Keep the water chemistry balanced frequently. Don’t let the water or tub freeze. Any apparent problems with the tub must be repaired immediately or else the problems will get worse.

If you perform these kinds of tasks regularly, then you’ll enjoy a functional pump and spa for many years.