Replacing Pumps
in Hot Tubs & Spas
 SpaCyclopedia Index Plumbing Diagrams Hot Tub Wiring Shop for Hot Tub Spa Pumps

A common problem with aging spas is pump failure.  We'll guide you through the process of replacing a spa pump... thus restoring your hot tub for many more years of use & enjoyment.  If your system is more than 2 or 3 years old, we recommend replacement of the entire pump, not just the motor or wet end-- you'll have fewer headaches in the long run.

See Spa Equipment Troubleshooting for details on repairing components.

CAUTION: Electrical repairs can be dangerous, especially around water. Repairs must be made by a qualified electrician or spa technician. Regardless of who performs the work, make certain that all electrical power to the hot tub or spa is disconnected prior to making any inspections or repairs.

Shut the  power off at the service panel, and as a secondary precaution, disconnect the power to the spa as well. Do not attempt to perform electrical repairs unless you are qualified.


Anatomy of Hot Tub Pumps

Hot tub pump parts Pumps are basically comprised of two main components: the wet end containing an impeller (which moves the water) and the electric motor (the dry end) which turns the impeller.

Symptoms of Spa Pump Failure

There are several signs of hot tub pump failure:

  • Malfunctions that prevent the motor from turning,  including frozen shaft or bearings, may result in a humming noise.
  • A jammed impeller (inside the wet end) can do  the same, as can a defective starting capacitor.
  • Badly worn bearings may cause a whining noise.
  • Leaks around the pump often indicate a failure of the pump seals.  You will likely observe a puddle of water below the pump when these seals go bad.

You could replace these individual components (if you can find the proper parts).  But if your pump is more than a couple years old, it is generally better to replace the entire pump-- motor and wet end.  This is a cleaner and much easier repair, which results in a greater reliability factor in the long run.  Our quality Replacement Spa Pumps are not expensive.  In fact, we charge less for complete brand-new pumps (motor and wet end) than others charge for just the motor alone!


Removing the Old Pump

Spa Equipment Access

The best way to assure obtaining the correct replacement pump, is to remove the old unit prior to ordering the new one.  This will allow you to make inspections and measurements to assure a correct match.

Equipment bay
Photo courtesy: Belize Spas
After disconnecting the electrical power, remove the spa's access panel.

Identified here in the hot tub's equipment bay:

  1. Hot tub pump
  2. Equipment control system

Some spas will have two gate or slice valves installed at either side of the pump (1).  If so, close these valves prior to removing the pump.  If no valves are present, drain the spa.

Disconnecting the Old Spa Pump

Spa pump removal
  • Disconnect the bare copper bonding wire from the pump's ground terminal.
  • Unscrew the pump's two unions.  Some residual water will drain out.
  • Remove the mounting screws from the pump base bracket.

Although the pump's power cable is still attached to the control system, the pump can now be lifted out of the equipment bay.

Cable Detachment

The old power cable* will be used for the replacement pump, if in serviceable condition.  Loosen the cable clamp screws. The pump end will also have an a removable access cover with terminal connections inside.

  pump cable

Remove the cable, making a note of wire color codes and connections.  Make sure the wire ends are clean for a good connection to your new pump. If necessary, snip off an inch or two, and restrip the wires. Most spa pumps are two speed units, with the low speed used for filtration and heating cycles. Two speed 240V pumps have 4 wires: red, black, white, and green.  Red is normally low speed, and black high speed.  The white wire is common and the green is ground.

*Note:  If you are also purchasing a new EasyPak spa control system from us, there is no need to save the old pump cable, as a new one is provided with the new spa pack.

Determine Pump Voltage & Horsepower

While all 110-120V spas use 120V pumps,  not all spas wired for 220-240V use 240V pumps.  Some use 120V pumps.  So check your owner's manual, and look at the label on the old pump to determine the voltage.  The label should also indicate the horsepower and amperage.  See pump specifications for a cross reference.

Some people desire to increase the spa jet action by upgrading to a larger pump.  This is generally not a problem if the spa's control system and the electrical service can accommodate the added amperage. As a rule of thumb, do not increase the pump horsepower more than one level of magnitude.  For example, upgrading a 1 HP pump to 1.5 HP, or a 3 HP pump to 4 HP is reasonable.  Avoid jumping from 2 HP to 5 HP as such a radical increase may cause problems like cavitation, uncomfortable jet pressure, or excessive current draw.

Determine Form Factor: Side or Center Discharge

The two spa pump form factors refer to the outflow or discharge fitting on the Wet End, as shown here. Your old pump will be either Center Discharge or Side Discharge.

Pump discharge forms Center Discharge
Side Discharge

Wet ends can be rotated

  Orientation of Wet End

Pump wet ends can be oriented in 90° increments.  Loosen the pump's four through bolts from the back of the motor and pull them back enough to disengage.  Then rotate the wet end to the desired position, realign and re-tighten the bolts.

In most cases you need to match the existing form factor to get the components to match up. If you can use either form, select Side Discharge which is more efficient than a Center Discharge pump of the same horsepower. See Pump Selection Chart

Circulation pumps
Continuous Circulating Pumps
In addition to the main pump, some spas also utilize a small continuous circulation pump.  Most spa circ pumps have 3/4" barbed fittings for flex hose, which makes replacement very easy.  See Circulating Pumps

Motor Frame Size

The physical size of the spa pump motor is referred to as frame. Spa main pumps will have a size of either 48 frame, which are approx. 5.5" diameter, or 56 frame, which are approx. 6.5" diameter. Check the old motor's ID plate for frame size.

48 Frame Motor

If in doubt, you can easily determine a motor's frame size by measuring the spacing between the through-bolts.

Bolt spacing on a 48 frame motor will be less than 4 inches. A 56 frame motor's bolts will be spaced more than 4 inches apart.

Note: Because of their lower cost and compact size, most spa pumps in service are 48 frame. Larger 56 frame motors are a little more expensive and somewhat stronger. They tend to operate a bit cooler than 48 frame units, which can mean longer service life.

56 Frame Motor

Determine Pump Plumbing Size
by Measuring O.D. of Male Wet End Threads

Plumbing size is very important, but a lot of people get it wrong and end up ordering the wrong pump. Most spa pumps use either 1.5" or 2" plumbing fittings, and a few have 2.5" intake suction. These are pipe call-out sizes, not fitting measurements.

Pump Plumbing With the pump unions removed, measurement is simple. The easy way to get it right for most* brands of hot tub pumps is by measuring the overall outside diameter (O.D.) of the pump's threads:
1.5" Pump

1.5" Pump thread measures approx. 2-3/8" O.D.

2" Pump
2.0" Pump thread measures approx. 3" O.D.
2.5" Intake

2.5" Pump (intake) thread measures approx. 3-5/8" O.D.

Note: These pumps normally have a 2.0" discharge thread fitting, which measures approx. 3" O.D.

*Note: Some brands of pumps (such as Hayward, Jacuzzi, and Sta-Rite) use non-standard fittings with different dimensions.  Please contact our Parts Technical Help for assistance with these if in doubt.

Installing the New Pump

The installation of your replacement pump is essentially the reverse of the removal process described above.  Once again, verify that the power is disconnected from the spa before proceeding.

Connecting Pump Power Cable

Most spa pumps are two speed units, with the low speed used for filtration and heating cycles.  As explained below, two speed pumps can easily be configured for single speed use.

Wiring new pump
  • Remove a wiring plug from the new pump motor end and install a cable connector clamp.
  • Remove the wiring access cover from the end of the new pump motor.
  • Attach the pump power cable wires and ground per pump's wiring diagram.
  • Replace access cover.
  • Tighten cable clamp.

Make sure the wire ends are clean for a good connection to your new pump. Our replacement pumps have a label diagram showing the wiring scheme.

Pump Speed Configuration

Pump Speed

A two-speed pump requires 3 line connections, plus a ground wire. The typical color coding is as follows:

  • White: common
  • Black: high speed
  • Red: low speed (left blank for 1-speed use)
  • Green (or bare): ground

Refer to the wiring diagram on your pump, as some equipment systems use different color coding. Wire orientation may vary on different pump brands.

One Speed Pump Configuration: A two speed spa pump can serve single-speed duty (common in dual pump hot tubs) by using only the common and high speed terminal connections, while leaving the low speed terminal blank.

Note: After pump replacement, If your spa filtration or heating cycle comes on with high speed instead of low speed, this normally indicates that the high and low speed wires simply need to be switched.

Setting Up the New Pump

  • Reattach the bare copper bonding wire to the pump grounding terminal.
  • Set the pump in place, carefully aligning it to the union connections.
  • Start the base mount screws, but do not tighten them yet.
  • Hand tighten the unions.  Do not use a wrench.
  • Tighten the pump base screws.

You may be able to reuse your old unions, or you can order new ones to match your plumbing size.  We also have a special reducer union (#BX9924) which will convert a 2" pump to match 1.5" spa plumbing.

Most spa pumps are designed for below water level (flooded suction) installation, to make certain that they fill with water. Their unions are compression fittings which should be correctly aligned with the male wet-end threads to allow the integral O-ring to seat properly.

Flooding the Pump

After installation and wiring hookup, but prior to powering-on the spa, make certain to open the valves (if so equipped) to flood the pump and prevent an air lock.  If you have drained the spa, refill it with fresh water.

IMPORTANT:  Now purge the pump of any remaining air pockets by loosening the pump unions until all air has escaped (you'll hear it)-- then hand retighten.  Running a pump dry will cause damage and void the warranty.

Testing and Inspection

  • Inspect the installation to verify that everything is properly connected.
  • Mop up any spilled water.
  • Reconnect power source.
  • Operate spa for a few minutes and observe for leaks or air locks.
  • Replace equipment bay access door.
About Voltage Numbers
In the U.S., standard household voltage (the voltage at regular wall outlets) varies from about 110 to 120 volts.  TVs, computers, lights, etc. are designed to run at this range.  Major appliances such as water heaters and clothes dryers, are usually wired at double that amount, which will typically be in the range of 220 to 240 volts.  Spa motors will be designed for one of these two ranges, but keep in mind that a voltage specification of 115 volts actually means that it is designed to function correctly in the range of 110 to 120 volts; a device which specifies 230 volts actually means it will function correctly in the range of 220 to 240 volts.

Watts = Amps x Volts.  Amperage determines the size of wiring and circuit breaker/GFCI required, and is also a factor in what your equipment controls will accommodate.  Wattage is the total amount of power consumed.  Note that a 120 volt pump drawing 16 amps uses virtually the same amount of power (wattage) as a 240 volt pump drawing 8 amps.

Replacement Pump Specifications

Our replacement pumps are designed to equal or surpass OEM specifications.  We use only premium-quality Waterway® pump wet ends and brand new (not remanufactured) motors-- the best money can buy. These 2-speed pumps are easily configured for 1-speed use if needed.

Pump Speeds:
Low 1725 RPM
High 3450 RPM

Pump HP Volts Hi/Lo Amps In/Out Discharge Frame
BX4100-C1 .75 120 8.8/2.6 1.5" Center 48
BX4101-C1 1.0 120 11/2.9 1.5" Center 48
BX4101-S2 1.0 120 11/2.9 2.0" Side 48
BX4102-C1 1.5 120 13.8/3.8 1.5" Center 48
BX4102-S1 1.5 120 13.8/3.8 1.5 " Side 48
BX4102-S2 1.5 120 13.8/3.8 2.0" Side 48
BX4103-C1 1.5 240 6.5/2.5 1.5" Center 48
BX4103-S2 1.5 240 8/2.6 2.0" Side 48
BX4113-S1 2.0 240 8.4/3 1.5" Side 48
BX4104-C1 2.0 240 10.5/2.6 1.5" Center 48
BX4104-S2 2.0 240 10.5/2.6 2.0" Side 48
BX4110-S2 3.0 240 8.5/2.8 2.0" Side 48
BX4105-S2 3.0 240 10/3.4 2.0" Side 56
BX4108-S25 3.0 240 10/3.4 2.5"/2.0" Side 56
BX4106-S2 4.0 240 12/4.4 2.0" Side 56
BX4109-S25 4.0 240 12/4.4 2.5"/2.0" Side 56
BX4107-S2 5.0 240 16.4/4.8 2.0" Side 56
BX4111-S25 5.0 240 16.4/4.8 2.5"/2.0" Side 56

*Specifications subject to change without notice.


spa customers write  Consumer Reviews
Replacement Spa Pumps
"The new pump really made a difference in the hot tub's water flow and I will tell you we've noticed it also runs a lot quieter. My old spa is now purring like a kitten and getting good use once again. Thanks for all your help and for saving me $300+."

Terry Bacon
Toledo, OH

Replacement Spa Pumps
"I just wanted to post a little feed back, I am the type of person that let's busineses know when they do something right, or get it all wrong. I called one of the local franchise pool supply companies for a spa pump, the price they quoted me was over $100 more then the one I bought from you. Your free delivery was on time, and your website had exactly what I needed for wiring tips. I will definately go to your site when I need a new spa power pack, and will tell my friends that own spas about you.

You got it ALL right."

Bob Link
Merritt Island Florida



Waterway® is a trademark of Waterway Plastics - Manufacturer of Spa Pumps