🇺🇸 Waterway EX2 Spa Pump 3721621-1W — 3.0 HP 2-Speed 230V 56-Frame 2″ × 2″ Side Discharge

American-made high-performance jet pump — designed to replace Aqua-Flo XP2 and XP2e 56-frame pumps

♨️ Product Overview

The Waterway EX2 3721621-1W is a 3.0 HP continuous duty (marketed as 4.0 HP) dual-speed, 56-frame jet pump drawing 12.0 amps on high speed and 4.4 amps on low speed at 230V/60Hz. Designed, engineered, and manufactured in California, USA by Waterway Plastics — a company committed to innovation and excellence since 1973. The EX2 line was purpose-built to meet the demand for larger spa installations requiring more jets per pump. This pump features 2″ MBT connections on both suction (center) and discharge (side), with the wet end rotatable in 90-degree increments for flexible plumbing alignment. Equipped with the highest-quality Viton seals for exceptional chemical resistance (including saltwater/chlorine generator compatibility) and high-efficiency electrical motors custom designed for spa applications. Includes two 400-5570 pump unions that accept 2″ PVC pipe (thread diameter measures approximately 3″ OD). Cord is NOT included. The EX2 is the same physical size as the Gecko Aqua-Flo XP2 and XP2e, making it a direct substitute or retrofit replacement. This pump can also be wired for single-speed operation. UL and cUL certified. Backed by a 1-year manufacturer’s warranty. Motor brands may include US Motors, AO Smith Century, or others — Waterway reserves the right to supply different motor brands while maintaining identical specifications.

⚠️ IMPORTANT — MODEL UPDATE: Waterway has replaced part number 3721621-1W with the updated designation MX-40226-20. Customers who order 3721621-1W may receive MX-40226-20. As of October 2024, this pump is supplied with the 372-1621-H motor model rated 12A at 230V. Both part numbers identify the same pump — specifications and fitment are identical.

✨ Key Features

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

✅ 3.0 HP Continuous Duty / 4.0 HP Brake Torque — True continuous rated horsepower; 12.0A high-speed amperage defines actual performance

✅ Dual-Speed Operation — High speed (12.0A / 3450 RPM) for powerful hydrotherapy and low speed (4.4A / 1725 RPM) for quiet filtration

✅ Can Also Be Wired for Single-Speed — Connect only the high-speed terminal for 1-speed operation

✅ Direct Replacement for Aqua-Flo XP2 & XP2e — Same physical size, same volume envelope — drop-in retrofit

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

✅ Double Shielded Ball Bearings — Extended motor life and quieter operation

✅ High-Efficiency Custom Motor — Specifically designed for spa applications with automatic overload protection

✅ 56-Frame Motor — Quieter Operation — Larger motor runs cooler and quieter than 48-frame alternatives

✅ Unions Included — Two 400-5570 unions accepting 2″ PVC pipe come pre-packaged

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

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

🔧 Technical Specifications

Specification	Value
Manufacturer	Waterway Plastics (California, USA)
Model / Series	EX2 (Executive 2)
Part Number	3721621-1W
Updated Part Number	MX-40226-20 (same pump — Waterway’s new designation)
Current Motor Model	372-1621-H (as of Oct 2024)
Pump Type	Jet Pump — Side Discharge
Horsepower (Continuous Duty)	3.0 HP
Horsepower (Brake Torque / Marketing)	4.0 HP
Speed Settings	2-Speed (Dual Speed) — can also be wired as a single-speed
RPM	3450 (High) / 1725 (Low)
Voltage	220-230V
Frequency	60 Hz
Phase	Single Phase
High Speed Amperage	12.0 Amps
Low Speed Amperage	4.4 Amps
Frame Type	56 Frame (56Y) Thru-Bolt
Wet End Diameter	6.5″
Discharge Type	Side Discharge
Discharge Size	2″ MBT (Male Buttress Thread) — ~3″ / ~3.1″ OD
Suction Size	2″ MBT (Male Buttress Thread) — ~3″ / ~3.1″ OD
Suction Style	Center
Discharge Rotation	4 positions — 90° increments
Overall Length	17″
Weight	Approximately 43-52 lbs
Seal Type	Viton (PS-1000 series / 319-3100B)
Wet End Part Number	310-2380 (EX2 3HP 56FR 2″ SD) — also 310-2980 (EX2 3HP 48/56FR)
Unions	NOT INCLUDED
Cord	NOT INCLUDED
Certifications	UL, cUL (CE and TÜV on export models)
Country of Origin	Made in USA (California)
Warranty	1-Year Manufacturer’s Warranty

⚡ Electrical Requirements

Electrical Spec	Requirement
Supply Voltage	220-230V
Frequency	60 Hz
Phase	Single Phase
High Speed Amperage	12.0 A
Low Speed Amperage	4.4 A
Motor Speed	3450 / 1725 RPM
Overload Protection	Automatic (built-in thermal overload)
Cord Type Required	4-wire (2-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. The motor must be properly grounded and bonded per NEC requirements. Always refer to the wiring diagram on the motor. This is a dual-speed pump requiring a 4-wire cord for full 2-speed operation. To wire as single-speed only, connect only the high-speed terminal.

⚠️ Wiring Warning: The wiring lug positions for low speed, high speed, and common are NOT in the same sequence as some other versions of this pump or other brands. Always read the wiring diagram on your specific pump — do not assume wire positions match your old pump.

🔗 Compatibility Guide

Direct Replacement For

The Waterway EX2 3721621-1W is specifically designed as a direct replacement for:

Gecko Aqua-Flo Pumps:

• Aqua-Flo XP2 56-Frame pumps
• Aqua-Flo XP2e 56-Frame pumps (05334012-2040 and related models)
• Aqua-Flo Flo-Master series

Waterway Pumps:

• Waterway Executive 56-Frame pumps (earlier models)

LX Lingxiao Pumps:

• 56WUA400-II and WUA400 series (verify amperage and frame size match)

Spa Brands Using This Pump (OEM or Replacement):

• Master Spas (X320524, X320525)
• Watkins / Hot Spring / Caldera (0974101, 1431601-03 rev A, PUM22000951, PUM22901106)
• Morgan Spa (3721623-1W8C variant)
• Coast Spa
• Many other brands using Aqua-Flo XP2e or Waterway Executive pumps

EX2 Design Advantages Over XP2/XP2e

The EX2 was specifically designed by Waterway to meet demand for more jets per pump in larger spa installations. Key advantages include: same physical size as Aqua-Flo XP2 and XP2e (fits within the same volume envelope), premium Viton seals for saltwater compatibility, double shielded ball bearings, and high-efficiency motors custom designed for spa use.

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

💡 Important: Always verify frame size by measuring motor through-bolt spacing. Do NOT rely on HP labels — rely on the amperage sticker on the motor for accurate pump identification.

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📐 Alternate Part Numbers

Primary / Updated Designations

Part Number	Notes	Source
3721621-1W	Original Waterway EX2 part number	Parts4Tubs, all retailers
MX-40226-20 / MX4022620	Updated Waterway replacement designation (same pump)	SpaParts.com, ReedPoolProducts
3M21621-1W	Alternate designation (sometimes with Emerson motor)	ReedPoolProducts
3721621-0W	Related variant	ReedPoolProducts
3721621-1W5A	Sub-variant	ReedPoolProducts
3721621-0WR187	Sub-variant	ReedPoolProducts
372-1621-H	Current motor model designation (as of Oct 2024)	ReedPoolProducts
3721623-1W87	Related variant	ReedPoolProducts
3721623-1W8C	Morgan Spa variant	SpaGuts, ReedPoolProducts
WWP-10-1036	Distributor SKU	EZTestPools
806105371188	UPC barcode	EZTestPools
663001448006	UPC barcode (alternate)	ElectricMotorWarehouse

Gecko Aqua-Flo Cross-References (Replaces)

Part Number	Model	Source
05334012-2040	Aqua-Flo XP2e 3HP 2-Speed 230V	SpaGuts, ReedPoolProducts, Pool-Spa-Supplies
05334001-2	Aqua-Flo XP2	SpaGuts
05330002-2	Aqua-Flo XP2	SpaGuts
05334000-5	Aqua-Flo XP2	SpaGuts
05334019-5	Aqua-Flo	SpaPumpsAndMore
05334026-2	Aqua-Flo	SpaGuts
05325004-5	Aqua-Flo	SpaGuts
05825015-7	Aqua-Flo (2.5HP)	SpaGuts
05825489-2	Aqua-Flo	SpaGuts, ReedPoolProducts
05825001-2	Aqua-Flo	SpaGuts
05825685-2	Aqua-Flo	SpaGuts
05830685-2	Aqua-Flo	SpaGuts
05834005-2	Aqua-Flo	SpaGuts
05834006-2	Aqua-Flo	SpaGuts
05834009-2	Aqua-Flo	SpaGuts
05834014-2	Aqua-Flo	SpaGuts
05834021-2	Aqua-Flo (5.0 SPL)	SpaGuts
05834030-5	Aqua-Flo (3HP, Single Speed)	SpaGuts
05834036-5	Aqua-Flo	ReedPoolProducts
05230366-2	Aqua-Flo	SpaGuts
06625774-2	Aqua-Flo/Gecko	HotSpaPoolTub
06625787-2	Aqua-Flo/Gecko	SpaGuts
07830-1350	Aqua-Flo	Pool-Spa-Supplies
07830001-1	Aqua-Flo	SpaGuts
07830000-2	Aqua-Flo	SpaGuts
07830306-2	Aqua-Flo	SpaGuts
07830332-2	Aqua-Flo	SpaGuts
078306-1340	Aqua-Flo	Pool-Spa-Supplies
07826787-2041	Aqua-Flo	SpaGuts
07827343-2	Aqua-Flo	SpaGuts
07827743-2	Aqua-Flo	SpaGuts
07827778-2341	Aqua-Flo	SpaGuts
07726008-5	Aqua-Flo	SpaGuts
07127783-2	Aqua-Flo	SpaGuts
07327783-2	Aqua-Flo	SpaGuts
7827774-2	Aqua-Flo	SpaGuts

OEM Spa Brand Cross-References

Part Number	Brand / Application	Source
1-00-0145	OEM cross-reference	Pool-Spa-Supplies, SpaGuts
1-00-0146	OEM cross-reference (also listed as 01-00-0146WW)	Pool-Spa-Supplies, SpaGuts
1-00-0153	OEM cross-reference	SpaGuts
X320524	Master Spas	Pool-Spa-Supplies
X320525	Master Spas	Pool-Spa-Supplies
0974101	Watkins (old)	ReedPoolProducts
1431601-03 rev A	Watkins	SpaGuts
PUM22000951	Watkins / Hot Spring	ReedPoolProducts
PUM22901106	Watkins / Hot Spring	ReedPoolProducts
PUM22000558	OEM	SpaGuts
3721623-1W8C	Waterway EX2 (Morgan Spa)	SpaGuts, ReedPoolProducts
SPR1900	OEM cross-reference	SpaGuts
317095	OEM cross-reference	Pool-Spa-Supplies
5175-224	OEM cross-reference	Pool-Spa-Supplies
369852	Replaces (wet end 310-2980)	HotTubOutpost
3168033	OEM cross-reference	ReedPoolProducts
PF-30-2N22C6	Motor cross-reference	ReedPoolProducts
PF-30-2N22M6	Motor cross-reference	SpaPumpsAndMore
PRC504 / PRC505	Motor cross-reference	SpaPumpsAndMore
E62386	Motor cross-reference	SpaPumpsAndMore
14328015X	Motor cross-reference	SpaPumpsAndMore
WO156589	Motor cross-reference	SpaPumpsAndMore
5KCP49UN9096X	Motor only (GE motor — verify wet end match)	SpaGuts
PRC9089X	Motor cross-reference	SpaGuts

Waterway Cross-References

Part Number	Notes	Source
3721120-1W	Earlier Waterway model replaced by 3721621-1W	Pool-Spa-Supplies
430-0052	Energy Saver pump (also replaced by LX 56WUA400-II)	SpaPartsExperts
3721621-1D	Related single-speed Waterway EX2 variant	Various

Sundance / Jacuzzi Cross-References

Part Number	Notes	Source
05225427-2	TheraMax II (11.3A variant — verify amperage match)	SpaGuts
6500-902	Sundance TheraMax II (11.3A — verify amperage)	SpaGuts

Replacement Pump Components (Individual Parts)

Component	Part Number	Notes	Source
EX2 Wet End (3HP, 56FR, 2″ SD)	310-2380	56-Frame thru-bolt, includes volute, seal, impeller, wear ring, suction cover, o-ring, drain plug, screws	WaterwayParts.com, ReedPoolProducts
EX2 Wet End (3HP, 48/56FR, 2″ SD)	310-2980	Fits both 48 and 56 frame motors; replaces 369852	HotTubOutpost
Executive Wet End (3HP, 56FR)	310-1730	Executive (non-EX2) 56-frame 3HP wet end	HotTubOutpost
Seal (Waterway Standard)	PS-1000 / 319-3100B	Standard Waterway pump seal — American manufactured	HotTubPartsOfAmerica, Amazon
3HP Impeller	310-4070	Executive/EX2 3HP impeller — confirm HP by amperage chart	HotTubPartsOfAmerica
4HP Impeller	310-4190 / 310-4190B	4HP impeller (for 56-frame Executive wet end)	Amazon, HotTubPartsOfAmerica
Wear Ring (1-3HP)	319-1270	Larger size — for 1.5HP, 2HP, and 3HP pumps	HotTubOutpost
Unions	400-5570	2″ PVC pipe unions (2 included with pump)	ElectricMotorWarehouse
Union O-Rings	O-43	Replacement union gaskets	HotTubOutpost
Rubber Motor Base	319-0019	Vibration-dampening rubber motor mount	HotTubOutpost

⚠️ Impeller Selection Warning: Do NOT install a higher-HP impeller thinking it will increase performance. The 1-3HP and 4-5HP impellers use different size wear rings — mismatching will cause damage. Always select the impeller that matches your motor amperage, NOT the HP label on the pump.

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🛠️ Installation Requirements

Mounting

Requirement	Specification
Mounting Position	Horizontal — below water level (flooded suction)
Base	Solid, level surface with adequate drainage
Ventilation	Ample clearance around motor — ensure room for single OR dual capacitor configuration
Access	Sufficient clearance for maintenance and wet end rotation
Shut-Off Valves	Recommended on both inlet and outlet for future maintenance

Plumbing

Connection	Size	Notes
Suction	2″ MBT (Center)	~3″ / ~3.1″ outside thread diameter
Discharge	2″ MBT (Side)	~3″ / ~3.1″ outside thread diameter
Unions	INCLUDED — two 400-5570 (2″ PVC)	HAND TIGHTEN ONLY — do NOT use a wrench

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. Running dry causes immediate seal damage.

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

⚠️ Pressure Test Warning: New installations may require plumbing inspection. Pressure tests should not exceed 40 PSI. Ensure all air is removed from the system during testing.

⚠️ Discharge Rotation: The 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 dual-speed (4-wire) pump cord or purchase separately. The cord/plug is intended to mate with your spa pack connector.

⚠️ Capacitor Clearance: Motor may have single or dual capacitor mounted on top. Ensure adequate space in the pump bay for either configuration.

⚠️ Bonding & Grounding: Improper grounding can cause serious injury and damage the motor, voiding warranty. Follow all NEC requirements.

⚠️ GFCI Protection Required: All spa installations require GFCI protection per the National Electrical Code (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
Verify both speeds function	Monthly	Low speed should be noticeably quieter than high
Check amperage draw	Annually	High: ~12.0A, Low: ~4.4A 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 the seal area between motor and wet end
• Motor repeatedly trips the 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)
• One speed works but the other does not
• Excessive vibration even on solid mounting
• Amperage draw significantly different from rated values

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 EX2 wet end (310-2380 or 310-2980) comes pre-assembled with a new seal, impeller, wear ring, and all housing components — often more cost-effective than individual seal replacement.

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🎯 Ideal Applications

Application	Suitability	Notes
♨️ Hot tub jet pump (12.0A, 230V, 56-frame)	✅ Yes — Primary application	Designed for larger spa installations with many jets
♨️ Replacement for Aqua-Flo XP2/XP2e 56-frame	✅ Yes — Designed specifically for this	Same physical size, drop-in replacement
♨️ Replacement for Waterway Executive 56-frame	✅ Yes	Direct fit
♨️ Master Spas replacement (X320524/X320525)	✅ Yes	OEM cross-reference confirmed
♨️ Watkins/Hot Spring/Caldera replacement	✅ Yes	Multiple OEM P/Ns confirmed
♨️ Salt water / chlorine generator spas	✅ Yes	Viton seals provide chemical resistance
♨️ Spas with 2-1/2″ plumbing	❌ No	Port size mismatch
♨️ 115V spa installations	❌ No	This is a 230V pump only
🛁 Whirlpool bath	❌ No	Far too powerful for bath applications

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❓ Frequently Asked Questions

Q: Is this a 3.0 HP or 4.0 HP pump? A: Both ratings describe the same pump. 3.0 HP is the true continuous rated horsepower (Waterway’s own specification). 4.0 HP is the brake torque horsepower used in aftermarket marketing. The 12.0A high-speed amperage at 230V is the most reliable specification for replacement matching.

Q: What is the difference between 3721621-1W and MX-40226-20? A: They are the same pump. Waterway updated the part number designation. Customers ordering 3721621-1W may receive MX-40226-20. Specifications and fitment are identical.

Q: Will this replace my Aqua-Flo XP2e? A: Yes. The EX2 was specifically designed by Waterway to replace Aqua-Flo XP2 and XP2e 56-frame pumps. It fits within the same volume envelope — it is a direct drop-in replacement.

Q: Can I use this as a single-speed pump? A: Yes. Connect only the high-speed terminal and leave the low-speed terminal unconnected, using a 3-wire (1-speed) cord.

Q: Are pump unions included? A: Yes. Two 400-5570 unions accepting 2″ PVC pipe are included. HAND TIGHTEN ONLY — do not use a wrench.

Q: Is a cord included? A: No. This pump ships without a power cord. Reuse your existing cord or purchase separately. Always follow the wiring diagram on the motor — wire positions may differ from your old pump.

Q: What motor brand will I receive? A: Waterway reserves the right to supply different motor brands (US Motors, AO Smith Century, GE, Emerson, etc.) without notice. As of October 2024, the current motor model is 372-1621-H. Performance specifications remain the same regardless of motor brand.

Q: Is this pump compatible with salt water systems? A: Yes. The EX2 is equipped with premium Viton seals that provide exceptional chemical resistance, making it compatible with salt chlorine generators.

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

Q: What wet end does this pump use? A: The EX2-specific wet end 310-2380 (56-frame) or 310-2980 (fits 48 and 56 frame). The wet end comes complete with volute, seal, impeller, wear ring, suction cover, o-ring, drain plug, and screws.

Q: What are the port sizes? A: Both suction and discharge are 2″ MBT (Male Buttress Thread), measuring approximately 3″ to 3.1″ across the outside of the threads.

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. 3-5/8″ apart = 48-frame. Or measure diagonally: 5-3/4″ in X pattern = 56-frame, 5-3/16″ = 48-frame.

Q: Can I put a larger impeller in this pump for more power? A: No. Do NOT install a higher-HP impeller — it will strain the motor and cause overheating. The 1-3HP and 4-5HP impellers also use different size wear rings, so mismatching causes additional problems.

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 warranty (part only). Warranty begins on date of manufacture. Contact point of purchase for warranty claims.

📥 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

🏆 Why Choose the Waterway EX2 3721621-1W

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

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

✅ Double Shielded Ball Bearings — Extended motor life and quieter operation

✅ Direct Drop-In for Aqua-Flo XP2/XP2e — Same physical size, no plumbing modifications needed

✅ More Jets Per Pump — EX2 designed for larger spa installations with high jet counts

✅ High-Efficiency Custom Motor — Specifically engineered for spa applications

✅ UL and cUL Certified — Full North American safety certifications

✅ Proven Track Record — Waterway Plastics: innovation and excellence since 1973

✅ Extensive Cross-Reference Compatibility — Replaces dozens of Aqua-Flo, Watkins, Master Spas, and other OEM pump numbers

✅ 1-Year Manufacturer’s Warranty — Backed by an American manufacturer

🤝 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, seals, wet ends, impellers, and replacement parts available

✅ Dedicated customer service team

✨ Summary

The Waterway EX2 3721621-1W (updated designation MX-40226-20) is a 3.0 HP continuous duty (marketed as 4.0 HP) dual-speed, 230V/60Hz jet pump drawing 12.0 amps on high speed and 4.4 amps on low speed with a 56-frame (56Y) thru-bolt motor at 3450/1725 RPM. Made in California, USA by Waterway Plastics. This pump features 2″ MBT suction (center) and 2″ MBT side discharge (~3″/3.1″ OD each), with 4-position discharge rotation. Wet end diameter 6.5″, overall length 17″. Same physical size as Aqua-Flo XP2 and XP2e — designed as a direct drop-in replacement. Equipped with premium Viton seals for salt water compatibility and double shielded ball bearings. Replaces Aqua-Flo 05334012-2040, Master Spas X320524/X320525, Watkins 0974101/PUM22000951, Waterway 3721120-1W, Energy Saver 430-0052, and dozens of other OEM part numbers. Unions INCLUDED (two 400-5570). Cord NOT included. Can be wired for single-speed operation. UL and cUL certified. Current motor model 372-1621-H (as of Oct 2024). 1-year manufacturer’s 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: 271 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: 952 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: 117 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: 492 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.