📥 Downloads & Resources

📄 56-Frame Executive Pump Installation Manual (PDF) — Official Waterway 56-frame instructions, wiring diagram with color codes, troubleshooting, and exploded view diagram

🔋 Waterway Executive 56 Spa Pump — 2.0 HP 2-Speed 230V (3720821-1D)

Powerful 56-frame motor with energy-efficient split capacitor design for premium spa performance

♨️ Product Overview

The Waterway Executive 56 (3720821-1D) is a 2.0 HP, 2-speed jet pump designed, engineered, and manufactured in the USA by Waterway Plastics of Oxnard, California. This is the standard 2 inch × 2 inch plumbing version of the Executive 56-frame series, featuring a 56-frame motor that delivers added strength, cooler operating temperatures, and longer motor life compared to 48-frame equivalents. The large 6-1/2 inch diameter Executive wet end provides higher head pressure and energy efficiency, while the split capacitor (start and run) design reduces energy consumption. Operating at 8.0 amps on high speed and 3.0 amps on low speed at 230V/60Hz, the motor features two double-shielded ball bearings with moisture-resistant grease for quieter operation and four sets of insulated windings for increased efficiency. The wet end features silicone carbide seals with Viton bellows and 316 stainless steel casing for superior corrosion resistance against chlorine, bromine, and salt systems. Thermally protected with a rotatable wet end adjustable every 90 degrees. Maximum overall length is 15-1/8 inches. This pump does not include unions or a pump cord.

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✨ Key Features

• ✅ 2.0 HP Dual-Speed Motor — High speed (8.0A / 3,450 RPM) for powerful jets, low speed (3.0A / 1,725 RPM) for quiet filtration
• ✅ 56-Frame Motor — Larger frame provides added strength, cooler operating temperature, and longer motor life
• ✅ Made in the USA — Designed, engineered, and manufactured by Waterway Plastics in Oxnard, California
• ✅ Executive Wet End — Large 6-1/2 inch diameter wet end specifically designed for 56-frame motors, delivering higher head pressure
• ✅ Double-Shielded Ball Bearings — Two moisture-resistant greased bearings for quieter operation and longer bearing life
• ✅ Split Capacitor Design — Start and run capacitor configuration for reduced energy consumption
• ✅ Silicone Carbide Seal System — Viton bellows and 316 stainless steel casing for corrosion resistance against chlorine, bromine, and salt
• ✅ Four Sets of Insulated Windings — Dual-speed motor design for increased electrical efficiency
• ✅ Thermal Overload Protection — Automatic motor protection extends life expectancy and prevents overheating
• ✅ Rotatable Wet End — Can be rotated every 90 degrees for flexible installation alignment
• ✅ Standard 2″ × 2″ Plumbing — 2 inch intake and 2 inch side discharge (thread OD approximately 3-1/16 inches)

🔩 Technical specifications

⚠️ Note: Waterway reserves the right to change motors used in their OEM pumps at any time. Capacitor location may be external or internal depending on the motor manufacturer supplied.

🔗 Alternate Part Numbers & Cross-References

This Pump Is Also Known As:

Part Number	Description
3720821-1D	Current OEM Waterway part number
37208211D	Same part number without dashes
PF-20-2N22C	Older Waterway model number (Century/A.O. Smith motor)
PF-20-2N22M	Older Waterway model number (U.S. Motors motor)
PF-10-2N22M	Updated Waterway model number (replaces PF-20-2N22C)
3720821-1DHZW	Variant with Century/A.O. Smith motor
3720821-1DHZN	Variant with U.S. Motors motor
3720821	Base model number (without suffix)

⚠️ Motor Brand Note: The last letter in PF- model numbers (C or M) and suffix codes (HZW or HZN) only reference the motor brand — C / HZW = Century/A.O. Smith, M / HZN = U.S. Motors. This does not need to be matched when selecting a replacement pump. Waterway has produced up to 4 known variations of pumps with the same PF- prefix, so the PF- number from an old pump should not be used as the sole reference for selecting a replacement.

This Pump Replaces:

Part Number	Notes
301897	Cross-reference replacement
3710821-1D	1-speed version of same Executive 56 2HP pump
3720821	Earlier version without suffix
3M20821	Alternate format part number
5039-208	Cross-reference replacement
673903	Cross-reference replacement

Compatible Spa Brands (Per Authorized Distributors):

• Beachcomber (Master Massage pumps — 1.5HP and 2HP)
• Arctic Spas
• Other 56-frame spa systems with 2″ × 2″ plumbing and 230V power

Related Waterway Executive 56-Frame 2HP Models:

Part Number	Plumbing	Description
3720821-1D	2″ × 2″	This pump — standard plumbing
3720821-13	2-1/2″ × 2″	Larger intake version
3720821-1W	2″ × 2″	EX2 version (higher jet capacity)
3710821-1D	2″ × 2″	1-speed version

🔧 Parts and fittings for this

Commonly replaced parts

Parts commonly replaced on this item that we stock.

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⚡ Electrical Requirements

Wiring Color Code (Per Waterway Manual 810-0199):

Wiring Notes (Per Waterway Manual):

• For wiring instructions, refer to the wiring diagram on the motor nameplate or on the back of the terminal cover.
• Applied voltage must correspond to rated voltage as indicated on the marking plate.
• All wiring must conform to local, state, and/or national codes.
• Ground motor prior to connecting electrical power. Do NOT ground to a gas supply line.
• 2-Speed models: Do NOT wire both speeds to run simultaneously.

⚠️ IMPORTANT ELECTRICAL SAFETY:

• All electrical work must be performed by a licensed electrician in accordance with the National Electrical Code (NEC) and local building codes.
• Hot tubs require GFCI (Ground Fault Circuit Interrupter) protection.
• A dedicated circuit is required — do not share with other appliances.
• Improper grounding can cause serious injury and damage to the motor, voiding the warranty.
• If the supply cord is damaged, it must be replaced by a special cord or assembly available from the manufacturer or its service agent.
• The pump cord is NOT included. Reuse your existing pump cord or purchase a compatible replacement separately.

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🔄 Compatibility Guide

This Pump:

• 📍 Frame: 56 Frame
• 📍 Wet End Diameter: 6-1/2 inches
• 📍 Suction (Intake): 2 inch (Thread OD approximately 3-1/16 inches)
• 📍 Discharge: 2 inch (Thread OD approximately 3-1/16 inches) — Side Discharge
• 📍 Discharge Rotation: Every 90 degrees
• 📍 Unions: Waterway male union threads — unions NOT included

Union Compatibility Note:

Unions are NOT included with this pump. There is no industry standard for pump unions — various brands have their own unique style and thread size. When replacing a pump from another brand, you may need to cut off your old unions and install compatible Waterway unions (sold separately).

⚠️ Important Replacement Tip: Do not select a replacement pump based on horsepower alone. HP ratings on hot tub pumps are often listed as SPL-HP, BHP, MBHP, RHP, or S-HP, which differ from continuous operating horsepower. Instead, confirm the frame size (48 vs 56) and match the high-speed amperage rating from the old pump’s label for an accurate replacement.

Other Executive 56-Frame 2-Speed Models (Manufacturer Data):

Part Number	Plumbing	HP	Amps (High/Low)	Weight
3720821-1D	2″ × 2″	2 HP	8.0 / 3.0 A	34 lbs
3720821-13	2-1/2″ × 2″	2 HP	8.0 / 3.0 A	34 lbs
ME-30226-20	2″ × 2″	3 HP	10.0 / 3.4 A	37 lbs
ME-40226-20	2″ × 2″	4 HP	12.0 / 4.4 A	44 lbs
ME-40226-25	2-1/2″ × 2″	4 HP	12.0 / 4.4 A	44 lbs
3722021-1D	2″ × 2″	5 HP	16.4 / 4.8 A	47 lbs
3722021-13	2-1/2″ × 2″	5 HP	16.4 / 4.8 A	46 lbs

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🛠️ Installation Requirements

Mounting (Per Waterway Manual 810-0199):

Requirement	Specification
Mounting Position	Horizontal, on level surface
Location	Must be installed below water surface (flooded suction)
Base Surface	Level surface, clear of direct water with adequate floor drainage
Moisture Protection	Pump should be protected from excessive moisture
Ventilation	Motor louvered openings must be free from debris and obstructions
Shut-Off Valves	Should be installed on both inlet and outlet for future maintenance

Plumbing:

Connection	Size
Suction (Inlet)	2 inch (Waterway male union threads, Thread OD ~3-1/16″)
Discharge (Outlet)	2 inch (Waterway male union threads, side, Thread OD ~3-1/16″)
Unions Included	No — sold separately

Plumbing Notes (Per Waterway Manual):

• Use Waterway tailpiece assemblies for best connection. Unions allow pump removal for service without disturbing the plumbing.
• HAND TIGHTEN UNIONS ONLY — Do NOT use a wrench or any adhesives or solvents.
• Do NOT use pipe dope. Use only Teflon tape or other sealing compounds approved for use with plastic. Some pipe dopes will cause stress cracking of plastic parts.
• Pressure tests should not exceed 40 PSI. Ensure all air is removed during pressure testing.

Installation Notes:

• ⚠️ Pump must be installed below water level (flooded suction)
• ⚠️ Do NOT run the pump without water — if pump fails to prime within 30 seconds, turn it off and check for air lock, clogged plumbing, or closed valves
• ⚠️ Ensure proper grounding and bonding per NEC requirements
• ⚠️ GFCI protection is required by code for all hot tub and spa installations
• ⚠️ Wet end ships at factory default discharge position — loosen the 4 motor thru-bolts on the back of the motor to rotate if needed

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🔧 Maintenance Guide

Routine Maintenance:

Task	Frequency	Notes
Check for leaks	Monthly	Inspect around seal plate and union connections
Inspect unions	Monthly	Hand tighten only if needed
Keep motor clean	Ongoing	Ensure louvered openings are free from debris and obstructions
Check amperage draw	Annually	Should match rated values (8.0A high / 3.0A low) within 10%
Inspect mounting	Quarterly	Ensure pump is secure and level
Check shaft seal	Periodically	Over time, seals may become damaged or worn and must be replaced

Warning Signs — Replace Pump If:

• Unusual noise (grinding, screeching, bearing noise, or rotor rub)
• Water leaking from the seal area
• Motor repeatedly trips the circuit breaker
• Noticeably reduced water flow through jets
• Motor overheating or shutting down during operation
• Motor hums but won’t start (capacitor or winding switch failure)

Seal Replacement:

• 📍 Seal Material: Silicone Carbide face / Viton Bellows / 316 Stainless Steel Casing
• 📍 Compatibility: Waterway Executive 56 frame pumps
• ⚠️ Replace seal at first sign of leakage to prevent motor damage

Winterization (Per Waterway Manual):

To prevent damage during freezing conditions, disconnect all electrical power, drain the pump thoroughly, and clean out any debris. Protect pump and motor from elements by covering, or if possible, store in a dry, well-ventilated room.

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🎯 Ideal Applications

Application	Suitability	Notes
♨️ Hot tub jet pump	Yes	Primary application — high speed for jets, low speed for filtration
♨️ Spa circulation	Yes	Low speed provides quiet, energy-efficient circulation
🛁 Whirlpool bath	Yes	Compatible with permanently installed whirlpool bath systems using 230V power

⚠️ Per Waterway: This pump is for use with permanently installed pools and may also be used with hot tubs and spas if so marked. Do not use with storable pools.

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❓ Frequently Asked Questions

Q: What horsepower is this pump? A: The Waterway Executive 3720821-1D is rated at 2.0 HP per the manufacturer’s official specification table at waterwayplastics.com.

Q: Will this fit my hot tub? A: This pump has a 56 frame with 2 inch intake and 2 inch side discharge (thread OD approximately 3-1/16 inches on both). To confirm compatibility, check your existing pump for: (1) frame size — 48 or 56, (2) port sizes, and (3) high-speed amperage rating on the pump label. Matching amperage is more reliable than matching horsepower alone.

Q: What is the difference between this pump (3720821-1D) and the 3720821-13? A: The 3720821-1D has standard 2 inch intake and 2 inch discharge (both ~3-1/16″ thread OD), while the 3720821-13 has a larger 2-1/2 inch intake (~3-5/8″ thread OD) and 2 inch discharge. All other specifications (HP, amps, frame, motor, weight) are identical. Choose based on your existing plumbing size.

Q: What about the HZW and HZN variants? A: The 3720821-1DHZW has a Century/A.O. Smith motor, while the 3720821-1DHZN has a U.S. Motors motor. The OEM 3720821-1D may ship with either motor brand — Waterway reserves the right to change motor suppliers. All variants have identical performance specifications.

Q: What voltage does this pump require? A: 230V / 60Hz. All electrical installation must be performed by a licensed electrician with GFCI protection. Verify your existing voltage before ordering.

Q: Is this a single or dual speed pump? A: This is a 2-speed pump. High speed (8.0A) delivers powerful jet massage at 3,450 RPM, while low speed (3.0A) provides quiet filtration and circulation at 1,725 RPM.

Q: What size are the ports? A: Both suction (inlet) and discharge (outlet) are 2 inch Waterway male union threads. The outside diameter across the pump threads measures approximately 3-1/16 inches on both connections.

Q: Are unions or a pump cord included? A: No, unions and pump cord are NOT included with this pump. You can reuse your existing pump cord or purchase a compatible replacement. When removing the power cord from an existing pump, mark your wires for “common,” “high speed,” and “low speed.”

Q: Can I rotate the discharge direction? A: Yes. The wet end ships at the factory default discharge position. To rotate, loosen the 4 motor thru-bolts on the back of the motor and turn the pump head. The discharge can be rotated every 90 degrees.

Q: What seal does this pump use? A: Silicone carbide face with Viton bellows and 316 stainless steel casing. This premium seal system provides superior corrosion resistance against chlorine, bromine, and salt systems.

Q: Is this pump made in the USA? A: Yes. Waterway Plastics designs, engineers, and manufactures their Executive pumps in Oxnard, California, USA.

Q: What does the PF- model number mean? A: The PF- model number is Waterway’s internal designation. The updated model number PF-10-2N22M replaces the older PF-20-2N22C. The last letter (C or M) references only the motor brand and does not need to be matched. Waterway has produced up to 4 known variations with the same PF- prefix, so this number alone should not be used for selecting a replacement.

Q: What warranty is included? A: 3-year manufacturer warranty on motor and wet end per Waterway’s published catalog specifications. Contact Parts4Tubs for full warranty terms and claims.

Q: How much does this pump weigh? A: 34 lbs per the manufacturer’s official specification.

Q: Do I need a GFCI breaker? A: Yes, GFCI (Ground Fault Circuit Interrupter) protection is required by the National Electrical Code (NEC) for all hot tub and spa installations.

🏆 Why Choose the Waterway Executive 3720821-1D

• ✅ Made in the USA — Designed, engineered, and manufactured by Waterway Plastics in Oxnard, California for over 50 years
• ✅ 56-Frame Advantage — Larger motor runs cooler, stronger, and lasts longer than 48-frame equivalents
• ✅ Lower Amperage, Same Power — 8.0A high speed vs. 10.5A on the 48-frame 2HP, delivering the same 2.0 HP more efficiently
• ✅ Double-Shielded Bearings — Moisture-resistant grease-packed bearings for quieter, longer-lasting operation
• ✅ Premium Seal Technology — Silicone carbide with Viton bellows and 316SS casing resists chlorine, bromine, and salt corrosion
• ✅ Energy Efficient — Split capacitor design and four insulated windings reduce energy consumption
• ✅ Thermal Overload Protection — Automatic motor protection prevents overheating and extends pump life
• ✅ Wide Replacement Compatibility — Replaces multiple part numbers including 301897, 3M20821, 5039-208, 673903, and PF-20-2N22C
• ✅ 3-Year Warranty — Manufacturer warranty on both motor and wet end

🤝 Why Buy From Parts4Tubs

• ✅ US-based support for American customers
• ✅ Fast shipping across the United States
• ✅ Expert advice from spa and hot tub specialists
• ✅ Competitive pricing in USD
• ✅ Full warranty support
• ✅ Hassle-free returns
• ✅ Replacement seals, wet ends, and pump parts available
• ✅ Dedicated customer service team

🌟 Summary

The Waterway Executive 3720821-1D is a 2.0 HP, 2-speed, 230V American-made jet pump featuring a 56 frame, standard 2 inch × 2 inch plumbing, large 6-1/2 inch Executive wet end with premium silicone carbide/Viton/316SS seal system, and rotatable discharge for flexible installation. With double-shielded ball bearings, split capacitor design, and four sets of insulated windings, this 34 lb pump operates efficiently at 8.0/3.0A (3,450/1,725 RPM) and replaces multiple legacy part numbers. Backed by a 3-year manufacturer warranty on motor and wet end. Order today from Parts4Tubs for fast US shipping and expert support.

Find the right pump or motor

Enter what is printed on the label of the one you are replacing. Anything that differs is shown with the difference spelled out, so you can judge it for yourself.

EitherComplete pumpMotor only

Make or modelHorsepowerVoltageAny115V230VSpeedAny1-speed2-speedVariable speedAmpsPort size (pumps)Any3/4 in1 in1-1/2 in2 in2-1/2 inFrame (motors)Any48Y48 frame56Y56J56C56 frame

Clear

Port size is the plumbing thread, not the pipe — a 2 inch union measures about 3 inches across the male thread. Amps are compared to within half an amp, since published figures round differently between motor brands. Voltage is never treated as a near miss: a 115V motor is not one step from a 230V supply. Anything whose page does not publish a figure you entered is left out rather than offered with a caveat — search it by name to see it anyway.

Unions and pump cords: pick the union size that matches your pump's ports (see the size chart below), and a 4-wire cord for a 2-speed pump.

Hot Tub Pump Collar & Union Size Chart

Imperial & Metric Specifications

Union Size	Collar Size	Thread OD	Union OD	O-Ring Size
1.5" Female Buttress Thread (FBT)	2.5" / 64mm (Tip to Tip) Measurement	2-1/2" 64mm	2-13/16" 71mm	2-5/16" OD 59mm
2" Female Buttress Thread (FBT)	3.1" / 78mm (Tip to Tip) Measurement	3-1/16" 78mm	3-3/8" 81mm	2-15/16" OD 75mm
2.5" Female Buttress Thread (FBT)	3.6" / 91mm (Tip to Tip) Measurement	3-5/8" 91mm	4-1/4" 108mm	3-7/16" OD 87mm

Important Notes

The union "size" (1.5", 2", 2.5") is nominal and doesn't correspond to any actual measurement.

Collar size is measured from thread tip to thread tip on the pump outlet.

Most hot tub pumps use Female Buttress Thread (FBT) - 98% of applications.

O-ring gaskets may vary between manufacturers - measure your existing gasket for accuracy.

How do I Replace a Hot Tub Pump?

Here's a general step-by-step guide on how to replace a hot tub pump. Keep in mind that the specific steps may vary depending on your hot tub's make and model, so it's essential to consult your hot tub's manual for model-specific instructions. If you're not comfortable with this procedure, it's a good idea to seek professional assistance.

Materials You'll Need:

• Replacement pump
• Screwdriver
• New union O-rings
• A strap wrench, only if a union nut is stuck
• PVC primer and cement, only if you are gluing in new tailpieces

Procedure:

1. Turn Off the Power: Before you begin, ensure the hot tub's power supply is turned off at the circuit breaker or disconnect switch. Safety should always be a priority when working with electrical components.

2. Drain the Hot Tub: If your hot tub is not already empty, you'll need to drain it. Follow your hot tub's manual or manufacturer's instructions for proper draining. (You might not need to do this if you can lock the pump off with the gate valves)

3. Locate the Pump: Identify the location of the existing pump in your hot tub. It's usually located near the equipment area or in a designated pump compartment.

4. Disconnect the Electrical Wiring: Carefully disconnect the electrical wiring from the old pump. This typically involves removing the electrical conduit cover, unscrewing wire nuts, and disconnecting the wires from the terminals. Be sure to note the wire connections or take a picture for reference when connecting the new pump.

5. Disconnect the Plumbing: Depending on your hot tub's plumbing setup, you'll need to disconnect the plumbing connections to the pump. Unscrew the union nuts by hand. If one is stuck, use a strap wrench rather than a pipe wrench, which can crack the nut. Be prepared for some water spillage when disconnecting the plumbing.

6. Remove the Old Pump: Once the electrical and plumbing connections are detached, carefully remove the old pump from its mounting position. Some pumps may be secured with mounting brackets or bolts.

7. Prepare the New Pump: If the new pump is not pre-assembled, you may need to attach fittings, unions, or adapters to match your hot tub's plumbing. Pump unions use buttress threads that seal on an O-ring, so fit new O-rings and hand-tighten the nuts. Do not use thread tape, pipe dope or sealant on them.

8. Mount the New Pump: Position the new pump in the same location as the old one and secure it in place using the mounting brackets or bolts.

9. Reconnect Plumbing: Reconnect the plumbing to the new pump, hand-tightening the union nuts. If you are gluing in new PVC tailpieces, use PVC primer and cement on those joints.

10. Reconnect Electrical Wiring: Reconnect the electrical wiring to the new pump, following the notes or pictures you took earlier. Make sure all wires are properly connected and secure.

11. Turn On the Power: Restore power to the hot tub by switching on the circuit breaker or reconnecting the disconnect switch.

12. Test the Pump: Turn on the hot tub's pump to ensure that it's working correctly. Check for any signs of leaks or irregularities in the plumbing connections.

13. Refill the Hot Tub: Once you've confirmed that the new pump is functioning properly, refill the hot tub with water.

14. Check for Leaks: Inspect the plumbing connections for any leaks. If you find any, turn off the pump, drain the tub again, and reseal the connections as needed.

15. Monitor: Keep an eye on the pump and plumbing for the next few days to ensure everything is functioning correctly and that there are no further issues.

Remember that this is a general guideline, and the specific steps may vary based on your hot tub's design. If you're unsure or uncomfortable with any aspect of this process, please do get in touch, happy to help.

How do I know what size hot tub pump I have?

Determining the size of your hot tub pump is an important step when it comes to maintenance or replacement. To find out the size of your hot tub pump, follow these steps:

1. Check the Manual: The easiest way to determine the size of your hot tub pump is to consult the owner's manual or user documentation that came with your hot tub. The manual typically contains detailed information about the specifications and components of your hot tub, including the pump.

2. Look at the Pump Housing: If you don't have access to the manual or it doesn't provide the information you need, inspect the pump itself. Most hot tub pumps have a label or plate on the pump housing that displays essential details, including the pump's model number, manufacturer, and specifications. You can then send that to me or Google it.

3. Measure the Pump: If the label is missing or damaged, you can measure the pump's dimensions. Measure the diameter of the pump's wet end (the part where the water flows) and the length of the wet end. These measurements can help identify the size and capacity of the pump.

4. Consult the Manufacturer: If you can't find the information on the pump or in the manual, contact the hot tub manufacturer or a reputable dealer. Provide them with your hot tub's model and serial number, and they should be able to identify the correct pump size for your specific hot tub.

5. Online Research: You can also search online using the pump's model number or hot tub's make and model. Many manufacturers provide detailed information about their products on their websites, and you may find specifications for your pump model.

Once you have determined the size and specifications of your hot tub pump, you can proceed with maintenance, repairs, or replacement if necessary. Keep in mind that replacing a hot tub pump with the same size and capacity as the original is crucial to ensure proper water circulation and filtration in your hot tub. If you're unsure about any aspect of this process, get in touch, always happy to help.