How To Choose The Correct Replacement Spa Pump

This guide discusses the procedure for selecting a replacement spa pump. Matching up the motor and wet end will make life easy when installing the new spa pump.
For manufactured spas, it is critical to find a pump that is close as possible to a drop-in replacement. The spa pumps are usually in a small place and there isn't much room to do any modifying of the plumbing.

1. FIND IDENTICAL MODEL - The easiest way to match up a pump is to get the same make and model. Look for a pump model number or part number. In our example, the Waterway pump model number is SD-10-1N11MC.

The majority of older spa pumps will either have an outdated model number that doesn't cross-reference to a current number or it won't have a legible number. If that is the case, proceed to step 2.

Note: The pump model number will be different from the motor model number that is on the motor specification label.

2. SPA PUMP COMPONENTS - There are two main components that you will need to identify. The first is the motor. The second is the "wet end". The wet end is the plastic or fiberglass part that is secured to the motor.

3. IDENTIFY MOTOR SPECIFICATIONS  - Find the following specifications on the motor label. These specifications will provide a baseline of what to look for in a replacement spa pump.

  • Horsepower (HP)
  • Voltage
  • Amps
  • RPM (3450 = Single Speed) (3450/1725 = 2-Speed)
  • Frame (FR)

Note: The HP rating listed on the label may not always be accurate. If you are unsure if the HP is accurate, look at the amp rating of the existing motor and compare that to the amp rating of a new pump with the same HP. There should not be a big discrepancy in amp rating. An am rating difference of more than 20% may be a sign that the original HP is not accurate. 

4. IDENTIFY WET END FEATURES -  In steps 5-7, the following spa pump wet end features will need to be identified.

  • Frame (Also Identified in Step 3)
  • Port Location
  • Port Size

5. FRAME - The frame of a spa pump wet end is typically 48Y or 56Y. The frame type can be found on the motor specification level. If not, measure the distance between the thru-bolts.

  • Less Than 4" = 48Y
  • 4" or More = 56Y

6. PORT LOCATION - Matching up the port arrangement can make life easier when it comes time to connect the new spa pump to the plumbing. This is especially true for manufactured spas.

The suction port is located at the front of the wet end and the discharge port is located at the top or side of the wet end.

7. PORT SIZE - Most spa pumps are sold with 1.5", 2", 2.5" ports. Those port sizes refer to the plumbing size and not the measurements of the actual wet end ports. To figure out what you need, measure the outside diameter of the suction and discharge part. Below are the common measurements as they relate to the listed port size.

  • Approximate Measurement of 2-3/8" = 1.5" Ports
  • Approximate Measurement of 3" = 2" Ports
  • Approximate Measurement of 3-5/8" = 2.5" Ports

Note : An easy formula to remember is to subtract 1" from the outside diameter measurement. That will give you the listed port size.

8. MATCH PUMP-Select a manufacturer and find a model that matches your spa pump requirements.

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If you have any other questions about pool and spa products please do let us know - we are here to help! 

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