💪 Waterway Executive 56 Spa Pump 3711621-1D — 4.0 HP 1-Speed 230V 56-Frame 2″ × 2″ Side Discharge

American-made dedicated jet pump with matched 2-inch ports — the industry standard for powerful hydrotherapy

📋 Product Overview

The Waterway Executive 3711621-1D is a 4.0 HP single-speed, 56-frame jet pump drawing 12.0 amps at 230V/60Hz. Made in the USA by Waterway Plastics — a leader in pool and spa equipment since 1973. This pump features matched 2″ MBT connections on both suction (center) and discharge (side) (~3″ / 3.1″ OD threads), making it the standard configuration for the vast majority of 56-frame spa installations. The large 6-1/2 inch diameter wet end is specifically designed for 56-frame motors to deliver higher head pressure, and the 56-frame motor provides cooler operating temperatures, added strength, and quieter operation versus 48-frame alternatives. Equipped with premium Viton seals for exceptional chemical resistance (including salt chlorine generator compatibility), two double-shielded ball bearings with moisture-resistant grease, and a split capacitor (start and run) design for reduced energy consumption with automatic thermal overload protection. The wet end can be rotated in 90-degree increments. This pump is a direct replacement for Master Spa X320500 and serves as a drop-in alternative to the Gecko Aqua-Flo XP2/XP2e and LX 56WUA400-I (verify amperage match). Motor brands may include AO Smith Century, US Motors, GE Marathon, or others. Cord and unions are NOT included. UL and cUL certified. Backed by a 1-year manufacturer’s limited warranty.

⚠️ CRITICAL — PORT SIZE: 2″ × 2″ (SAME SIZE PORTS). This pump (3711621-1D) has the same 2″ port on both suction and discharge (~3″/3.1″ OD threads). If your existing pump has a larger 2-1/2″ suction port (~3.7″ OD threads), you need the 3711621-13 instead. Measure your existing pump’s suction thread outside diameter to confirm.

⚠️ IMPORTANT — Model Number Warning: Waterway has changed the motor model designation from PF-40-1N22C to PF-30-1N22M — it is still the same pump. Do NOT use the PF- model number from your old pump to select a replacement, as Waterway has produced up to 4 known variations with the same PF- number that are NOT interchangeable. Always match the Waterway part number (3711621-1D).

✨ Key Features

✅ Made in the USA — Designed, engineered, and manufactured by Waterway Plastics since 1973

✅ 4.0 HP Single-Speed — Powerful dedicated jet pump drawing 12.0 amps at 230V/60Hz, 3450 RPM

✅ Matched 2″ × 2″ Ports — Standard configuration for most 56-frame spa installations — both suction and discharge ~3″/3.1″ OD threads

✅ Large 6-1/2″ Diameter Wet End — Executive wet end specifically designed for 56-frame motors delivers higher head pressure

✅ 56-Frame Motor — Cooler & Quieter — Larger motor runs at lower temperatures for added strength and longer life

✅ Viton Seals — Premium chemical-resistant seals compatible with salt chlorine generators and aggressive sanitizers

✅ Double-Shielded Ball Bearings — Moisture-resistant grease for quieter operation and extended bearing life

✅ Split Capacitor Design (Start & Run) — Reduced energy consumption compared to capacitor-start-only motors

✅ Thermal Overload Protection — Automatic motor protection extends life expectancy

✅ 4-Position Wet End Rotation — Rotates every 90° for flexible plumbing alignment

✅ Direct Replacement for Master Spa X320500 — Also replaces Aqua-Flo XP2/XP2e, LX 56WUA400 series, and Watkins/Hot Spring pumps

✅ UL and cUL Certified — Full North American electrical safety certifications

✅ 1-Year Manufacturer’s Limited Warranty — Backed by Waterway Plastics

⚙️ Technical Specifications

Specification	Value
Manufacturer	Waterway Plastics (USA)
Series	Executive 56-Frame
Part Number	3711621-1D
Motor Model	PF-40-1N22C (older) / PF-30-1N22M (current) — same pump
Pump Type	Jet Pump — Side Discharge
Horsepower	4.0 HP
Speed Settings	1-Speed (Single Speed)
RPM	3450
Voltage	230V
Frequency	60 Hz
Phase	Single Phase
Amperage	12.0 Amps
Frame Type	56 Frame (56Y) Thru-Bolt
Wet End Diameter	6-1/2″
Discharge Type	Side Discharge
Discharge Size	2″ MBT — ~3″ / ~3.1″ OD threads
Suction Size	2″ MBT — ~3″ / ~3.1″ OD threads
Suction Style	Center
Discharge Rotation	4 positions — 90° increments
Dimensions (H × W × L)	9.08″ × 8.05″ × 14.775″
Seal Type	Viton (PS-1000 / 319-3100B)
Impeller Part Number	310-4190 / 310-4190B (4.0 HP Executive 48/56 Frame)
Wet End Part Number	310-1740 (4HP, 56FR, 2″ × 2″ SD)
Bearings	Double-shielded ball bearings with moisture-resistant grease
Capacitor	Split capacitor (start and run)
Motor Protection	Thermal overload (automatic)
Cord	NOT INCLUDED
Unions	NOT INCLUDED — sold separately
Certifications	UL, cUL
Country of Origin	Made in USA
Warranty	1-Year Manufacturer’s Limited Warranty

🔌 Electrical Requirements

Electrical Spec	Requirement
Supply Voltage	220-240V (230V nominal)
Frequency	60 Hz
Phase	Single Phase
Amperage	12.0 A
Motor Speed	3450 RPM
Overload Protection	Automatic thermal overload (built-in)
Cord Type Required	3-wire (single-speed) pump cord — NOT included
Certifications	UL, cUL

⚠️ IMPORTANT ELECTRICAL SAFETY:

All electrical installations must be performed by a licensed electrician in accordance with the National Electrical Code (NEC) and local building codes. This 230V pump must be connected to a supply circuit protected by a Ground-Fault Circuit Interrupter (GFCI). A dedicated circuit is required — do not share with other appliances. Improper grounding can cause serious injury and damage the motor, voiding the warranty. Always refer to the wiring diagram on the motor.

⚠️ Wiring Warning: Always follow the wiring diagram on your specific pump. Motor model changes (PF-40-1N22C → PF-30-1N22M) may alter terminal positions. Do not assume wire positions match your old pump.

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🔄 Compatibility Guide

CRITICAL: 3711621-1D vs 3711621-13 — Different Port Configurations

Model	Suction (Intake)	Discharge (Outlet)	Thread OD (Suction)	Thread OD (Discharge)
3711621-1D (THIS PUMP)	2″ MBT (Center)	2″ MBT (Side)	~3″ / ~3.1″	~3″ / ~3.1″
3711621-13	2-1/2″ MBT (Center)	2″ MBT (Side)	~3.7″	~3″ / ~3.1″

⚠️ These are NOT interchangeable without plumbing modifications. Measure the outside diameter of the threads on your existing pump’s suction port: approximately 3″ / 3.1″ = 2″ (order 3711621-1D); approximately 3.7″ = 2-1/2″ (order 3711621-13).

Direct Replacement For

Master Spas:

• X320500 — Waterway part numbers 3711625-0D8QMR and 3711625-0D8PMR

Watkins / Hot Spring / Caldera:

• 39578-03

Gulf Coast Spas:

• 9099X 7135 (GE Marathon motor variant)

Compatible With (Verify Amperage):

• Gecko Aqua-Flo XP2 / XP2e 56-Frame 4HP 1-Speed (same physical size as EX2 variant)
• LX Lingxiao 56WUA400-I (verify 12.0A amperage match — LX rated same amperage)
• Any spa using a 56-frame, 230V, 12.0A, 1-speed pump with 2″ × 2″ plumbing

Frame Size Reference

Frame	Bolt Pattern (Adjacent)	Bolt Pattern (Diagonal)
48-Frame	3-5/8″ apart	5-3/16″ in X pattern
56-Frame (THIS PUMP)	4-1/8″ apart	5-3/4″ in X pattern

Waterway Executive 56-Frame 4HP Family (All Port/Speed Variants)

Model	Speed	Ports (Suc × Dis)	Amperage	Notes
3711621-1D (THIS PUMP)	1-Speed	2″ × 2″	12.0A	Standard ports
3711621-13	1-Speed	2-1/2″ × 2″	12.0A	Oversized suction
3721621-1D	2-Speed	2″ × 2″	12.0/4.4A	Standard ports, dual-speed
3721621-13	2-Speed	2-1/2″ × 2″	12.0/4.4A	Oversized suction, dual-speed

Union Requirements (NOT Included — Sold Separately)

Port	Union Part Number	Description
Suction (2″)	400-5570	2″ FBT × 2″ slip
Discharge (2″)	400-5570	2″ FBT × 2″ slip
Union O-Ring	O-43	2″ union o-ring (need 2)

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📐 Alternate Part Numbers

Primary / Also Known As Designations

Part Number	Notes	Source
3711621-1D	Primary Waterway Executive part number (2″ × 2″)	Parts4Tubs, all retailers
3711621-1DHZN	OEM Waterway replacement designation	HotTubOutpost
3711621-1DHZW	OEM Waterway with Century motor	HotTubOutpost
37116211D	Concatenated format	SpaPumpsAndMore, Pool-Spa-Supplies
3711621	Base model number (without suffix)	HotTubOutpost, Pool-Spa-Supplies
3M11621	Alternate designation	HotTubOutpost, Pool-Spa-Supplies, EZPools
3711621-0V98	Sub-variant	Pool-Spa-Supplies
3711621-0D6Z	Sub-variant	HotTubOutpost
PF-40-1N22C / PF401N22C	Older motor model designation	Pool-Spa-Supplies, SpaPumpsAndMore, PoolAndHotTubDepot
PF-30-1N22M	Current motor model designation (same pump — Waterway changed P/N)	PoolAndHotTubDepot, SpaPumpsAndMore
PF-45-1N22C	Alternate motor model designation	SpaPumpsAndMore, Pool-Spa-Supplies
PF-40-1N22M	Alternate motor model designation	SpaPumpsAndMore

Distributor / Retailer SKU Cross-References

Part Number	Source / Notes
304855	Pool-Spa-Supplies, HotTubOutpost
5039-401	INYOPools, Pool-Spa-Supplies
673901	Pool-Spa-Supplies, HotTubOutpost
15586	Pool-Spa-Supplies
WW37116211D	Pool-Spa-Supplies, HotTubOutpost
WWP-10-1018	Pool-Spa-Supplies, HotTubOutpost

OEM Spa Brand Cross-References

Part Number	Brand / Application	Source
X320500	Master Spas	Pool-Spa-Supplies
3711625-0D8QMR	Waterway / Master Spas variant	Pool-Spa-Supplies
3711625-0D8PMR	Waterway / Master Spas variant	Pool-Spa-Supplies, SpaPumpsAndMore
39578-03	Watkins / Hot Spring / Caldera	Pool-Spa-Supplies
5KCP49UN9099X	GE Marathon motor (motor only — verify wet end match)	SpaQuip
9099X 7135	Gulf Coast Spa (GE Marathon motor variant)	SpaQuip
806105076205	UPC barcode	HotTubOutpost

Related 2-1/2″ × 2″ Version (DIFFERENT Wet End — Same Motor)

Part Number	Notes	Source
3711621-13	Executive 4HP 1-Speed 230V 2-1/2″ × 2″ (LARGER suction)	Parts4Tubs, all retailers
3711621-13HZW	Century motor variant (2-1/2″ × 2″)	HotTubOutpost
301919	Cross-reference (2-1/2″ × 2″)	EZPools
5039-402	Cross-reference (2-1/2″ × 2″)	EZPools
K63MWENE-4731	Motor cross-reference (2-1/2″ × 2″)	EZPools
WW371162113	Distributor code (2-1/2″ × 2″)	EZPools
WWP-10-1456	Distributor SKU (2-1/2″ × 2″)	EZPools

⚠️ WARNING: The 3711621-1D (2″ × 2″) and 3711621-13 (2-1/2″ × 2″) have the SAME motor but DIFFERENT wet ends. Cross-reference part numbers listed for the -13 version apply ONLY to spas with 2-1/2″ suction plumbing.

Related Viking Spa Variant

Part Number	Notes	Source
81560	Viking Spa 4HP Executive 1-Speed — includes equipment cord	HotTubOutpost
3711621-0D7Z	Replaced by Viking 81560	HotTubOutpost

Replacement Pump Components (Individual Parts)

Component	Part Number	Notes	Source
Wet End (4HP, 56FR, 2″ × 2″)	310-1740	Complete: volute, seal, impeller, wear ring, suction cover, o-ring, drain plug, screws. Motor & unions sold separately.	HotTubOutpost, Pool-Spa-Supplies
Wet End (4HP, 56FR, 2-1/2″ × 2″)	310-1440	For -13 version — DIFFERENT suction size	HotTubOutpost, Pool-Spa-Supplies
4HP Impeller	310-4190 / 310-4190B	Executive 48/56 Frame 4.0 HP impeller	SpaCare, Amazon, HotTubPartsOfAmerica
Seal (Viton)	PS-1000 / 319-3100B	Standard Waterway Executive seal — American manufactured	SpaCare, HotTubPartsOfAmerica
Faceplate (2″ suction)	311-1220	Executive 48/56 Frame — 2″ suction cover	SpaCare
Faceplate (2-1/2″ suction)	311-1210	For -13 version — DIFFERENT suction size	SpaCare
Faceplate O-Ring	805-0261	Executive 48/56 Frame suction cover o-ring	SpaCare
Drain Plug O-Ring	805-0111	Executive 48/56 Frame	SpaCare
Wear Ring (4-5HP)	319-1370	DIFFERENT from 1-3HP wear ring (319-1380)	SpaCare
Wear Ring (1-3HP)	319-1380	NOT for this pump — different size	SpaCare
56-Frame Volute	315-1220 / 315-1220B	Executive 56-frame housing	SpaCare, HotTubOutpost
Union (2″ FBT × 2″ Slip)	400-5570	Both suction and discharge use same union	HotTubOutpost
Union O-Ring 2″	O-43	Union gasket (need 2 — one per port)	HotTubOutpost
Rubber Motor Base	319-0019	Vibration-dampening rubber motor mount	HotTubOutpost
Drain Plugs	715-1201	For faceplate 311-1220	HotTubOutpost

⚠️ Impeller Warning: The 4-5HP impellers use a different size wear ring (319-1370) than 1-3HP impellers (319-1380). Do NOT install a higher-HP impeller — it will overstrain the motor and cause overheating. Always match impeller to your motor’s amperage rating, NOT the HP label.

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🛠️ Installation Requirements

Mounting

Requirement	Specification
Mounting Position	Horizontal — below water level (flooded suction)
Base	Level surface with adequate drainage
Ventilation	Ample clearance around motor for air cooling
Access	Sufficient clearance for maintenance and wet end rotation
Shut-Off Valves	Recommended on both inlet and outlet for future maintenance

Plumbing

Connection	Size	Thread OD	Notes
Suction (Center)	2″ MBT	~3″ / ~3.1″	Connects to 2″ ID plumbing
Discharge (Side)	2″ MBT	~3″ / ~3.1″	Connects to 2″ ID plumbing

Installation Notes

⚠️ Flooded Suction Required: Pump must be installed below water surface for proper operation.

⚠️ Never Run Pump Dry: Ensure the pump is primed and filled with water before starting.

⚠️ HAND TIGHTEN UNIONS ONLY: Do NOT use a wrench or any adhesives or solvents. Do NOT use pipe sealant/pipe dope. Use only Teflon tape or sealing compounds approved for use with plastic. Some pipe sealants cause stress cracking in plastic parts.

⚠️ Pressure Test Warning: Plumbing pressure tests should not exceed 40 PSI. Ensure all air is removed from the system during testing.

⚠️ Discharge Rotation: Wet end can be rotated in 90-degree increments to align with existing plumbing.

⚠️ Cord NOT Included: This pump ships without a power cord. Reuse your existing single-speed (3-wire) pump cord or purchase separately. Always follow the wiring diagram on the motor.

⚠️ Unions NOT Included: Both suction and discharge use 400-5570 (2″ FBT × 2″ slip) unions with O-43 o-rings. Sold separately.

⚠️ Bonding & Grounding: Improper grounding voids warranty and creates electrical hazards. Follow all NEC requirements.

⚠️ GFCI Protection Required: All spa installations require GFCI protection per the NEC.

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🔧 Maintenance Guide

Routine Maintenance

Task	Frequency	Notes
Check for leaks	Monthly	Inspect around seal area, unions, and volute housing
Inspect plumbing connections	Monthly	Unions should be hand-tight only
Check amperage draw	Annually	Should be approximately 12.0A at 230V
Keep motor clean	Quarterly	Ensure all air openings are free from debris
Verify GFCI operation	Monthly	Press test button to confirm proper function
Check mounting and vibration	Quarterly	Motor base should be secure and level

Warning Signs — Replace Pump If:

• Unusual noise (grinding, screeching, or humming without rotation)
• Water leaking from seal area between motor and wet end
• Motor repeatedly trips circuit breaker or GFCI
• Noticeably reduced water flow or weak jets
• Motor overheating or burning smell
• Motor hums but won’t start (possible capacitor failure)
• Excessive vibration even on solid mounting
• Amperage draw significantly different from 12.0A

Seal Information

Detail	Specification
Seal Type	Viton
Seal Part Number	PS-1000 / 319-3100B
Material	High chemical resistance — compatible with salt chlorine generators

⚠️ Replace seal at first sign of leakage. The complete wet end (310-1740) comes pre-assembled with a new seal, impeller, wear ring, and all housing components — often more cost-effective than individual seal replacement.

⚠️ Seal Warning: The Waterway PS-1000 is NOT interchangeable with the Gecko Aqua-Flo PS-200 or LX SEAL-56WUA. Always match the seal to the wet end brand.

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🎯 Ideal Applications

Application	Suitability	Notes
♨️ Hot tub dedicated jet pump (12.0A, 230V, 56-frame, 2″ × 2″)	✅ Yes — Primary application	Most common 56-frame spa pump configuration
♨️ Master Spas replacement (X320500)	✅ Yes — Direct OEM replacement	Confirmed by Pool-Spa-Supplies
♨️ Watkins / Hot Spring replacement (39578-03)	✅ Yes	OEM cross-reference confirmed
♨️ Multi-pump spa systems (multiple jet pumps)	✅ Yes	Common in larger spas with dedicated jet zones
♨️ Salt water / chlorine generator spas	✅ Yes	Viton seals provide chemical resistance
♨️ Replacement for Waterway Executive/EX2 56F 4HP 1-speed (2″ × 2″)	✅ Yes	Direct fit
♨️ Spas with 2-1/2″ suction plumbing	❌ No — Wrong suction size	Use 3711621-13 instead
♨️ 115V spa installations	❌ No	This is a 230V pump only
♨️ Filtration/circulation duty	❌ No — Single-speed only	Use a 2-speed or dedicated circulation pump
🛁 Whirlpool bath	❌ No	Far too powerful for bath applications

❓ Frequently Asked Questions

Q: What is the difference between 3711621-1D and 3711621-13? A: Port sizes. The 3711621-1D (this pump) has 2″ suction and 2″ discharge — both ports the same size (~3″/3.1″ OD threads). The 3711621-13 has a larger 2-1/2″ suction (~3.7″ OD) and standard 2″ discharge. Both use the same motor but have DIFFERENT wet ends. Measure your existing pump’s suction thread outside diameter to confirm which you need.

Q: Is this a 4.0 HP pump? A: This pump is rated at 4.0 HP by Waterway. However, HP ratings on spa pumps can vary by rating method (SPL-HP, BHP, continuous, etc.) and may be overinflated. The 12.0A amperage at 230V is the most reliable specification for replacement matching.

Q: Why does my Waterway label show PF-40-1N22C? A: This is the motor model number, which Waterway has changed from PF-40-1N22C to PF-30-1N22M (same pump). Other variations include PF-45-1N22C and PF-40-1N22M. Do NOT use PF- model numbers to select replacements — Waterway has produced up to 4 different pump variations with the same PF- number.

Q: Will this replace my Master Spa pump X320500? A: Yes. The 3711621-1D is the direct replacement for Master Spa X320500. Waterway-specific part numbers for this application include 3711625-0D8QMR and 3711625-0D8PMR.

Q: Are unions included? A: No. Unions are sold separately. Both ports use 400-5570 (2″ FBT × 2″ slip) with O-43 o-rings. You need two unions (one per port).

Q: Is a cord included? A: No. This pump ships without a power cord. Reuse your existing single-speed (3-wire) cord or purchase separately.

Q: What wet end does this pump use? A: 310-1740 — the Executive 4HP, 56-frame wet end with 2″ MBT suction × 2″ MBT discharge (same port sizes). This is DIFFERENT from the 310-1440 (2-1/2″ × 2″) used on the 3711621-13. The wet end comes complete with volute, seal, impeller, wear ring, suction cover, o-ring, drain plug, and screws.

Q: What seal does this pump use? A: The Waterway PS-1000 (also known as 319-3100B) — a Viton seal. This is NOT the same as Gecko Aqua-Flo PS-200 or LX SEAL-56WUA.

Q: What impeller does this pump use? A: 310-4190 / 310-4190B — the Executive 48/56 Frame 4.0 HP impeller. Note: 4-5HP impellers use a different wear ring (319-1370) than 1-3HP impellers (319-1380).

Q: Can I upgrade to a 2-speed version? A: Yes. The 2-speed equivalent is 3721621-1D (12.0A/4.4A, 2″ × 2″). This requires a 4-wire cord and a spa pack that supports 2-speed pump operation. A 2-speed pump can be wired as single-speed, but a single-speed pump cannot be wired as 2-speed.

Q: What motor brand will I receive? A: Waterway reserves the right to supply different motor brands (AO Smith Century, US Motors, GE Marathon, etc.) without notice. Performance specifications (12.0A, 230V) remain the same.

Q: How does this compare to the LX 56WUA400-I? A: Both draw 12.0 amps at 230V and have the same 56-frame, 2″ × 2″ configuration. The Waterway Executive is Made in USA with Viton seals and double-shielded ball bearings. The LX is manufactured in China and is typically less expensive. Both are reliable pumps — the Waterway Executive commands a premium for its US manufacturing, premium materials, and brand heritage.

Q: How do I know what frame size my pump is? A: Measure the distance between consecutive motor through bolts. 4-1/8″ apart = 56-frame (this pump). 3-5/8″ apart = 48-frame.

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

Q: What warranty is included? A: 1-year manufacturer’s limited warranty from date of purchase (if installed by a qualified installer). Parts failing during the warranty period are repaired or replaced within 90 days. Warranty does not cover freezing, negligence, improper installation, or labor/shipping costs. Proof of purchase required. Register your product at waterway.com.

📥 Downloads & Resources

📄 Waterway 48/56 Frame Executive, EX2, & Viper Pump Installation Manual (PDF) — Official Waterway Plastics installation instructions for Executive, EX2, and Viper pump series

📄 Waterway Product Support — All Instruction Manuals — Waterway Plastics official download center for all product instruction manuals

📄 Waterway Executive 56-Frame Wet End Replacement Parts Catalog (PDF) — Official Waterway parts diagram for Executive 56-frame wet end components

📄 How to Rotate a Pump Wet End (PDF) — Step-by-step guide for rotating the discharge orientation

📄 How to Wire a Spa Pump (Guide) — Wiring reference for single-speed and 2-speed spa pumps

🌟 Why Choose the Waterway Executive 3711621-1D

✅ Made in the USA — Designed, engineered, and manufactured by Waterway Plastics

✅ Industry Standard 2″ × 2″ Configuration — The most common 56-frame spa pump port size — compatible with the widest range of installations

✅ Large 6-1/2″ Wet End — Higher head pressure for powerful jet performance

✅ Premium Viton Seals — Superior chemical resistance for salt water and aggressive sanitizer compatibility

✅ Double-Shielded Ball Bearings — Quieter operation and extended motor life

✅ Split Capacitor Design — Reduced energy consumption

✅ 56-Frame Motor — Cooler operation, added strength, and longer life than 48-frame alternatives

✅ Thermal Overload Protection — Built-in motor protection

✅ Direct Master Spas / Watkins Replacement — Confirmed OEM cross-references

✅ UL and cUL Certified — Full North American safety certifications

🤝 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

✅ Full warranty support

✅ Hassle-free returns

✅ Compatible pump cords, unions, seals, wet ends, impellers, and replacement parts available

✨ Summary

The Waterway Executive 3711621-1D is a 4.0 HP single-speed, 230V/60Hz jet pump drawing 12.0 amps with a 56-frame (56Y) thru-bolt motor at 3450 RPM. Made in the USA by Waterway Plastics. This pump features matched 2″ MBT center suction and 2″ MBT side discharge (~3″/3.1″ OD each) — the standard 56-frame spa pump configuration. Large 6-1/2″ diameter wet end designed specifically for 56-frame motors delivers higher head pressure. Dimensions: 9.08″ H × 8.05″ W × 14.775″ L. Premium Viton seals for salt water compatibility, double-shielded ball bearings, split capacitor design, and automatic thermal overload protection. Wet end rotates in 90° increments. Motor model changed from PF-40-1N22C to PF-30-1N22M — same pump. Direct replacement for Master Spa X320500 (3711625-0D8QMR/3711625-0D8PMR), Watkins 39578-03, and many other OEM applications. Also known as 304855, 3M11621, 5039-401, 673901, WWP-10-1018. Wet end 310-1740, impeller 310-4190, seal PS-1000/319-3100B, faceplate 311-1220, wear ring 319-1370, volute 315-1220. Unions NOT included (both sides use 400-5570 with O-43). Cord NOT included. UL and cUL certified. 1-year manufacturer’s limited warranty. Available now at Parts4Tubs with fast US shipping and expert compatibility support.

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	Magic Plastics Union 0602-15 (1.5″ Pump Union) | 1-1/2″S x 1-1/2″FBT Union, Pump, Magic, 1-1/2"S x 1-1/2"FBT (Industry Standard) w/ O-Ring	$6.36 Max: 586 Min: 1 Step: 1 Add to cart
	Magic Plastics Union 0602-20 (2″ Pump Union) | 2″S x 2″FBT w/ O-Ring Union, Pump, Magic, 2"S x 2"FBT (Industry Standard) w/ O-Ring	$8.00 Max: 535 Min: 1 Step: 1 Add to cart
	Waterway Union 400-6010 | 2-1/2″ Union Nut with 2-1/2″ Slip tailpiece and o-ring (2.5″ union) Union, Pump, Waterway, 2-1/2"FBT x 2-1/2"S	$14.77 Max: 150 Min: 1 Step: 1 Add to cart
	1 Speed Pump / Blower / AMP Cord | 21086 Amp Plug, Pump, 1-Speed, 14/3, 4-Pin, 5' Cord, White	$24.71 Max: 341 Min: 1 Step: 1 Add to cart
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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
• Pipe wrench
• Adjustable wrench
• Screwdriver
• Pipe sealant (thread tape or plumber's putty)
• PVC primer and cement (if you have PVC plumbing)
• Teflon tape (for threaded connections)

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. Use a pipe wrench or adjustable wrench to loosen and remove the fittings. 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. Ensure that you use the appropriate sealant or Teflon tape on threaded connections to prevent leaks.

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, ensuring that all connections are tight and secure. If your hot tub uses PVC plumbing, use PVC primer and cement to bond the connections properly.

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.