Waterway hot tub pump part number 3721221-13 is labeled with the model number PF-20-2N22M which is a 3HP rated Waterway Executive 56 spa pump featuring 2 speeds running on 220 - 240 volts. This model has the 2-1/2" intake which will measure about 3-5/8" outside to outside on the threads.
Discharge Threads
2.5" intake threads (Actual 3-5/8" OD).
2.0" discharge threads (Actual 3.0" OD).
Electrical Specs
10.0 Amps high speed (3450 RPM)
3.4 Amps low speed (1725 RPM)
220-240 Volts, 60 Hz
Discharge Position
Ships with discharge at factory default position.
Discharge can be rotated if required, Instruction Video
Compatible Replacement for:
Waterway P/N 3721221-03
Waterway PF-30-2N22C (With 2.5" intake)
Waterway PF-20-2N22M (With 2.5" intake)Whats Included:
1 x Waterway Pump P/N 3721221-13
(Electrical cord not included)
Product Note:
Optional barb P/N 672-4350 Sold Separately
For use in hot tubs only
Questions ? We can help, Contact UsIMPORTANT
The PF- model number from your old pump should not be used as a reference for selecting a new replacement pump as Waterway has produced up to 4 known variations of pumps with the same model number which are different enough that they are not interchangeable. Always select a replacement pump with the same part number as the Waterway part number on the label on your old pump.
The last digit "C" or "M" in the model number only references the brand of electric motors Waterway uses on these pumps and does need to be matched on the new replacement pumps. C references Century/A.O. Smith brand motor and M references U.S. Motors brand electric motor on the pump.
Horsepower ratings
Choosing a pump based on Horsepower (HP) can be incorrect. The horsepower listed in your spa manual or on the old pump's label may be overinflated, inaccurate, or even left blank. Horsepower ratings on hot tub pumps are often listed as SPL-HP, BHP, MBHP, RHP or S-HP, which is not the same as continuous operating horsepower. Installing an oversized pump in your hot tub can cause significant damage.
To avoid choosing the incorrect pump, confirm if it’s a 48 frame or 56 frame, then use the high-speed Amperage rating listed on the old pump's label to find the correct replacement instead of the horsepower. The amperage rating is listed with both high/low speed for a 2-speed pump.
Determining hot tub pump thread size
Hot tub pump plumbing sizes are nominal and not the actual outside diameter (O.D.) of the threaded intake or discharge. To confirm your old pump thread sizes, use a tape measure and check the diameter of your old pump thread size.
- 1.5” Pump thread measures approx. 2-3/8” Outside Diameter
- 2.0” Pump thread measures approx. 3” Outside Diameter
- 2.5” Pump thread measures approx. 3-5/8” Outside Diameter
Amperage ratings
New hot tub pump amperage ratings may vary slightly for pumps with the same performance rating. The RPMs remain the same 3450 for high-speed and single-speed pumps and 1725 for low-speed for two-speed pumps.
