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Replace a Hot Tub Pump

hot tub pumpReplacing a hot tub pump with a replacement pump requires knowing several things about the existing pump.

Write down the info from the existing pump label to be sure you get the correct replacement pump.

Voltage: 110 or 220 Volts?

Voltage Hot Tub PumpsWhat is the pump's voltage (usually 110-120v or 220-230v)?

For purposes of voltage identification, standard voltage pumps may be referred to as 110v, 115v or 120v interchangeably, or the pump may be a higher voltage 220v/230v pump.

This information is on the pump label.  It does not matter if the spa itself is hooked up to 220 volts or 110 volts because you may have a 220 volt spa with a 110 volt spa pump, so be sure to read the correct voltage of the pump you need off of the existing pump label and jot it down.

The correct replacement pump will operate at the same voltage as your existing pump.

The Amperage should be close too for single speed pumps or the high and low speed amp draw on a two speed pump. The high and low amps are also usually indicated on the existing spa pump label.  Make a note of that as well to compare with your replacement pump.

If the existing pump wire only has 3 wires (one being green/ground), then it is a 1-speed pump, but can be either 110v or 230v, so it is not automatically a 110v pump just because it only has 3 wires - check the existing pump label for correct pump voltage to match.

Note that all pumps shipped by Hot Tub Outpost are for use in North America at 60hz. If you require a European or export model 50hz spa pump, contact us.    

1-Speed or 2-Speed?

Pump speed single or dualDoes your replacement pump need to be a 1-speed or 2-speed pump? 

If you have to push the button twice to get the pump to go from low to high and then off, that is a 2-speed pump.

If it is just on and off, then it is wired for a 1-speed pump. 

Note that a 2 speed pump can be configured for 1 speed operation (by wiring only the high speed line) but a 1 speed pump cannot be wired for 2 speed operation.

Another way of checking if the pump is single speed or dual speed is if the label shows either 1 or 2 rpm ratings. For example a 3450/1725 RPM rating shows that it is a 2 speed motor/pump. A single 3450 RPM rating shows that your pump is using a 1 speed motor.  A single 1725 rpm rating means you have circ pump motor, ratings of 2850 rpm or 1425 rpm mean you have a 50 hertz overseas motor.

Hot Tub Outpost offers most major brand 1 and 2-speed pumps including Aqua-Flo, Waterway and discount custom pumps too.
Have a question about pump speeds? Contact us.

48 Frame or 56 Frame?  48FR or 56FR

Frame size pumpsThe frame size of spa pumps relates to the motor diameter and is usually given on the pump label, but can also be determined by measuring the distance between the through-bolts - those long bolts that go all the way through the motor and hold the wet end to the motor.  See the video instructions below on determining if the pump is 48 frame or the larger 56 frame,  or contact us for further information. 

With spa pumps, it is either one or the other - 48FR or 56FR - with the 56 Frame motors/pumps being larger. 

Another way to tell the difference is that 48 frame motors are about 5-1/2” in diameter and the 56 frame motors are about 6-1/2” in diameter on almost any brand spa pump. So measuring across the motor is another clue.

motor bolts distance

Measuring from adjacent carriage bolt to bolt, the 48 frame will be about 3 5/8" inches between bolts on the motor and the 56 frame will be wider - about 4 1/8" between adjacent bolts. This is another way to determine the size of the motor.

You can also measure across the diagonals of 2 of these 4 bolts that hold the pump to the wet end and go all the way through the motor housing. If you want to do a diagonal measurement between 2 of the opposite bolts, then it will be about 5 1/8" across a 48 frame motor and about 5 3/4" across a 56 frame motor.

Yet another way is to see if either a 5/16 or 1/4" socket fits on the through bolt. The 5/16" throughbolt is the 56 frame pump and if the throughbolts are 1/4" that means it is a 48 frame pump. So there are many ways to confirm what frame size your pump is.

It is easiest to just look at the old pump label and find "FR" and see if it says U48 or 56.

In the case of Waterway Executive Pumps, they already say either Executive 48 (48 frame) or Executive 56 (56 frame).

(Note if just replacing a wet end, that the wet end can have two different sizes depending on what motor it is mounting to. Some wet ends work with both 48 and 56 frame motors).

Another interesting little tidbit to help determine frame size of your pump is that 48 frame motors usually have 1/4” heads on the thru-bolts and the 56 frame motors would have thicker 5/16” bolt heads.

By now you should know if you need a 48 frame or 56 frame replacement pump, so jot that down and view the next section.

Typically, but not always, the 48 frame motors run lower horsepower applications and the 56 frame pumps run the 4HP, 5HP..spas. It is said that the 56 frame pumps, being larger, run cooler and quieter than their 48 frame cousins.  If you are mounting a pump to a spa floor and it runs loud, try damping it by mounting the pump on a pump vibration pad rather than directly to the floor of the spa.

Connections - Size of the 2 Pump Unions - Plumbing Size

pump union open spaPump Union Size ThreadBe sure to order the pump with the correct plumbing size so the replacement hot tub pump fits with your existing plumbing connections/unions without needing to change your plumbing connections.

The standard threaded connection is called 2" which actually measures a bit over 3 inches wide across both suction and discharge plumbing connections.

Typical hot tub plumbing connections to the pump are either:

  • 1 1/2" (2 7/16" actual diameter)
  • 2"       (3 1/16" actual diameter)
  • 2 1/2" (3 11/16" actual diameter)

Most spas use 2" plumbing for the main pump line.  Some circulation pumps though, may use even smaller connections, so know what your current plumbing size is on both the suction side and discharge side of the spa pump plumbing so that the new pump lines up nicely and you just need to hand tighten the two unions on the new pump.

Some of the Waterway Executive pumps use a 2 1/2" suction and a 2 inch discharge, in that case the suction male threaded fitting on the pump would measure about 3 11/16" in diameter which is called the 2 1/2" connection.  Now the actual inside diameter of both the 2 inch and 2 1/2 inch type connection openings on the pump measures about 2 1/4" - only the large nut is different on the 2 1/2" but you need to check the outer diameter of these threaded pump connections to be sure you get either a 2"x2" or 2 1/2"x 2" depending on your plumbing setup and pump union sizes.

When removing and replacing the pump unions attached to spa plumbing, be sure they each still have their o-ring inside to avoid water leakage at the union.  You can also buy new inexpensive pump o-rings to fit the same size as the pump union if needed.

Pump Wet End Orientation - Lining up the Plumbing

Hookup spa pump orientationwet end pump orientationYou will also need to note your pump's wet end orientation so that the wet end will line back up with your 2 plumbing connectors. 

If the wet end is not rotated correctly, this can still be done after you get your pump as most wet ends can be rotated in 90 degree increments to line up with existing plumbing.


       Side Discharge   Center Discharge

Some pumps have a center discharge while others have a side discharge.  Getting the same type of pump with center or side discharge helps the exsiting plumbing to line up when replacing the pump, although moving the top pipe a couple of inches is usually not a problem so that it lines up with the top opening on the pump.

What matters more is the wet end rotation as some plumbing is setup for side discharge pumps to hook up lower while others has the discharge hookup at the top of the pump.  It is good to know that in case your plumbing is different, you can rotate the wet end to line it up, or order it with the wet end rotated if the pump discharge does not come out the top as is normally the case.

On the wet end side of the pump where the impeller is turned by the pump motor to move the water, the suction connection is usually at the center of the wet end (except for some drain pumps that have them at the bottom). Most of the pumps you will find here have center wet end suction fittings/unions/threads so that is one thing you usually don't have to worry about.

Pump Cords
The cord that connects the pump to the spa pack or circuit board usually connects by either a 4 pin AMP plug, a J&J plug or mini J&J gray plug, or even bare wires to a terminal block.  Most of the time, you can use your existing pump cord on the new spa pump. Many spa pumps are sold without cords and the right type of cord is sold separately if you also need a pump cord.  If the description says the pump comes with a cord, it should say what type of connector is on the cord. 

Get the Info from the Existing Pump Label

If you can't read the details from the pump label because the pump is still in the spa, and don't want to take the bad pump out yet, maybe you can get a cellphone picture or use a mirror.

spa-circ-pump-label.jpgThe pump label of your current pump will provide much of the needed information to source a suitable replacement.

If you replace the pump brand/type with the same brand/type, you should still verify the details to be sure you get the right replacement pump.

Hot Tub Outpost carries a wide variety of spa pumps.  Don't see the one you need, send us an email and we will track 'er down. 

Replacing a Hot Tub Pump - Recap - Things to Know

Check the original pump motor voltage, not the voltage supplied to the spa for the correct pump voltage.

When reusing the original pump power cord you can label the wires for "Common", "High speed", "low speed" as most spa pumps do not come with a pump cord.  Typically there is a diagram on the motor name plate of the new pump to show the terminals to hookup on the pump. 

Pump wet ends can usually be rotated  in 90 degree increments by loosening the long motor through-bolts and turning to the position desired (discharge pointing to 3,6, 9 or 12 o'clock). Pumps usually come with the discharge pointing up/12 o'clock.

Plumbing size example: 2" refers to the inner diameter/nominal size of the attached PVC hose or pipe. It has nothing to do with the size of the union nuts, the measurement of the threads, the inside diameter of the inlet or any other measurement on the actual pump. The PVC pipe fits inside the slip connection of a union and is glued in place with PVC glue.

Example of 2 inch plumbing connection to a pump.

Plumbing Sizes

2" plumbing for example is 2" I.D.; 2 3/8" OD on the line with circumference = 8"

A 2-speec pump can be operated as a single speed pump by only connecting the high speed wire.

2" outlet measures 3" outer diameter across the threads, 2.5" inlet measures 3 5/8" outer diameter across the threads



More about amps and horsepower.  It is best to match the amps on the old pump to be similar to the one on the new pump rather than relying on stated horsepower ratings.

Given horsepower can be stated in different ways such as brake horse power, SPL vs operating or continuous duty horsepower.
Brake torque horsepower, SPL ratings and continuous duty/operating horsepower are all different ways to express motor horsepower.

Some manufacturers rate their own motors. SPL rating is a special rating per the manufacturers request. This allows the manufacturer to adjust the actual horsepower of the pump.

This number can be misleading when trying to find a compatible replacement pump. Brake horsepower is the amount of horsepower used to start the motor, not the actual running horsepower of the pump. This is why it is best to first narrow down pumps by frame size,voltage, plumbing size and then get close to matching the amperage or high speed amps for 2-speed pumps. 

Get great deals on replacement hot tub pumps with free shipping right here at the Hot Tub Outpost.

See the line of LX pumps for great value replacement hot tub pumps.

We also carry circulation pumps (24/7 circ pumps) such as those by Laing, Waterway, Grundfos or even Hush Pump type circulation pumps.

Have a question about replacing your pump?  Email us at for answers.

Why email?  Because that way you have a reference trail of text you can go back and refer to, and you can send pictures if needed. We also respond to your email requests lightning-fast.

Upgrade your hot tub experience with our powerful and reliable hot tub pumps. New pumps are designed to provide maximum water flow and superior performance, ensuring that you can fully relax and unwind in your hot tub. With a durable construction and energy-efficient design, new spa pumps are built to last and won't break the bank when you get one from Hot Tub Outpost with free shipping.

See our hot tub pumps for our current selection or contact us if you don't see the pump you need. We also offer huge discounts on pumps with rebuilt motors and new, brand name wet ends that come with a 1 year warranty.  From 3/4HP to 6HP and beyond.

Horse Sense
Warning: Working on your own appliances, cars, covered wagons and hot tubs as well as anything else electrical or mechanical carries with it severe risk of injury or property damage. These tips and suggested procedures are free and for informational purposes only. Proceed at your own risk. It is best to use the services of an electrician or tech. Hot Tub Outpost is not liable for any damage or injury that may result.

"Let's get the spa working again by replacing the motor".  Some people refer to the spa pump as the spa motor, while others want just the motor that attaches to the wet end of the pump.  Typically spa owners will either have the wet end replaced if it is leaking or if the impeller is jamming up, or they will replace the entire pump.  If you need just the motor, contact us as we sell those too.


Hot Tub Pump Troubleshooting

There are many reasons why a pump can go bad.  One common occurence is if the seal leaks between the wet end and the pump.  If water gets into the pump motor, then a short circuit can occur or the pump can lock up.

When needing to replace a pump, it is best to replace the entire pump instead of just the pump motor or wet end if the pump is over a few years old. It is also easier and you know the entire unit is brand new and functioning so you don't have to revisit the problem a few weeks down the road.


This video explains how to wire up a replacement spa pump.  Basically, you can still use the existing wire that is on your broken pump if it is serviceable. That way you already have the correct connector type that fits into your spa pack or onto your spa circuit board.  Connector types include J&J type 4 pin connectors, J&J mini connectors and white 4 pin AMP plugs.

When replacing a spa pump, line the new pump up to the fittings as close as possible. As long as you use new pump o-rings, you don't really need the silicone lubricant, but it doesn't hurt if you have some. The o-rings will do a perfect job of keeping water from dripping at the pump unions.

Note that you can rotate most wet ends in 90 degree increments to line up with your particular plumbing layout.  Be sure to order the correct pump type so the unions will fit the plumbing on the pump. Typically pump threaded male connectors are 2 inch connectors that fit onto 2 inch plumbing, but there are also 1 1/2 inch plumbing connections and even 2 1/2 inch connections on several spa types and brands, so be sure you order the correct replacement pump.

Circulation Pumps

circulation pumpsCirc pumps keep the water flowing through the filter 24-7 at a slower rate than dual purpose jet pumps that filter on low speed.  Circ pumps are either small frame (Grundfos, Laing, Tiny Might..) or 48 frame in size.  There are no 56 frame circ pumps. They can be 120v or 230v. and run on low amperage (usually under an amp).

See our collection of hot tub circ pumps.

24 hour circulation pumps are usually 1-speed pumps designed for continuous low flow.  So the ratings on a circ pump will show very low amperage compared to jet pumps.  The label will say for example FloMaster, Tiny Might, Iron Might, Laing and the frame size may be a 48 frame size or smaller.

For the 48 frame circ pumps, if it is a center discharge pump (meaning the discharge coming out the top is in the middle instead of off to the side), the that male threaded connection will be a 1 1/2" connection most of the time. The actual measurement is about 2 3/8" across the threaded dimension.  Some companies will use a 2 inch union adapter to the 1 1/2" connection.  Some smaller circ pumps like Laing have 3/4" barb connections (real diameter about 7/8").  Note the Waterway Tiny Might and Grundfos pumps use 1 inch connections (actual diameter measurement across threaded connector about 2 inches).

It is best to check the existing label to see the frame size and voltage.  Popular brands are Waterway, Aquaflo, Gecko and others.

Note that circ pump model numbers can be updated, so if you can't find the pump you need by model number, you can narrow it down by frame size (48 or small), voltage, the size of the 2 plumbing connections (suction and discharge), is it center or side discharge? 

Contact us with any questions if you need assistance in determining the right pump for your spa. You can send us a picture of the pump/pump label and any other details such as connection size and we will send you back the correct link for a replacement pump.

Warning: Working on your own appliances, cars, covered wagons and hot tubs as well as anything else electrical or mechanical carries with it severe risk of injury or property damage. These tips and suggested procedures are free and for informational purposes only. Proceed at your own risk. It is best to use the services of an electrician or tech. Hot Tub Outpost is not liable for any damage or injury that may result.

Does your pump leak?  See our page on repairing leaking spa pumps.

See our replacement spa pumps from 1HP to 5HP.

Or complete the form below and we will email you a link to the best available replacement pump based on your pump details: