Sundance Spas Waterway Executive Spa Pump: 3721621-13, 4 HP 2 Speed 2 1/2" Intake 2" Discharge 56 Frame 230 Volt Pump

Waterway Executive Pump 3721621-13
Description:
4 Horsepower
2 Speed
56 Frame
230 Volt
2 1/2" Intake and 2" Discharge
Do not mistake this pump for 3721621-1D which has a 2 inch intake and discharge

Features:

• Executive wet end designed specifically for 56 frame motors.
• Two double shielded ball bearings with moisture resistant grease for quieter operation and longer life.
• 56 Frame motor for added strength, cooler operating temperature and longer motor life.
• Large 6 1/2" diameter wet end for higher head pressure.
• Large 2 1/2" intake for improved flow performance and reduced noise.
• Split capacitor, (start and run) for less energy consumption.
• Thermally protected to extend life expectancy of motor.
• Highly versatile wet end can be rotated every 90 degrees.
• Viton Seals.

This has a 2.5 inch Suction and a 2 inch Return. See info below:

What the frame size on a spa pump mean?

The frame size on a spa pump is the physical size of the spa pump motor. The frame is the piece that mounts the wet end to the motor. The frame size is located on the motor's ID plate, usually marked with an F for frame size. The thru-bolt spacing is also an indicator of frame size. A 48 frame motor has bolts spaced less than 4 inches apart, and the 56 frame motor has bolts with spacing more than 4 inches apart.

How do I measure and know what size are the fittings on my pump?

Most spas use a 2 inch Union on the Suction and Return of the Pump. This size usually refers to the size of PVC that is used on the Union of the Pump, there are some, specifically Waterway that also uses a 2.5 inch Suction Fitting with a 2 inch Return fitting, so when you measure, these are the measurements that you will help determine the size of the Suction and Return Fittings: 2 inch threads measure 3 1/16 inch OD and 2 1/2 inch threads measure 3 5/8 inch OD.