💧 Little Giant P115 Cast Iron Circulation Pump – 1/40 HP 115V

Heavy-duty cast iron construction for reliable spa, baptismal, and hot water circulation applications

♨️ Product Overview

The Little Giant P115 is a 1/40 HP cast iron circulation pump manufactured by Franklin Electric under the Little Giant brand. Built with a professional-grade cast iron housing, this pump represents traditional circulator engineering designed for long-term reliability in hot water circulation applications including spas, hot tubs, baptismal pools, and hydronic systems.

Operating at 115V / 60Hz with a draw of just 0.52A, the P115 features a wet rotor design that eliminates the need for a mechanical shaft seal — the most common failure point in conventional circulation pumps. The self-lubricating wet rotor means no seal maintenance, no seal leaks, and no seal replacement throughout the pump’s lifetime. The 3/4″ FPT (Female Pipe Thread) connections on both suction and discharge provide a standard threaded interface that integrates easily with existing plumbing configurations.

The P115 is the Little Giant replacement for the widely used Taco 006-ST4 circulator and the baptismal pump model 611365. Its cast iron construction provides superior durability and vibration dampening compared to thermoplastic housings, while the compact inline design allows installation directly in the plumbing line without requiring a separate mounting pad or base plate. Backed by Franklin Electric’s decades of expertise in water system technology.

✨ Key Features

• ✅ Cast Iron Construction — Professional-grade cast iron housing provides superior durability, vibration dampening, and long-term reliability
• ✅ 1/40 HP Motor — Purpose-built for continuous duty circulation in low-flow heating and filtration applications
• ✅ 115V / 0.52A / 60Hz — Ultra-low power consumption for continuous 24/7 operation at minimal energy cost
• ✅ Wet Rotor Design — NO mechanical shaft seal to leak, wear, or replace — self-lubricating for maintenance-free operation
• ✅ 3/4″ FPT Suction & Discharge — Standard Female Pipe Thread connections on both ports for easy plumbing integration
• ✅ Single Speed — Simple, reliable single-speed operation with no complex electronics
• ✅ Inline Installation — Compact design mounts directly in the plumbing line without separate base plate or mounting bracket
• ✅ Replaces Taco 006-ST4 — Direct replacement for the widely used Taco 006 series circulator
• ✅ Baptismal Pool Rated — Proven in baptismal pool circulation and hot water applications
• ✅ Franklin Electric Quality — Backed by a global leader in water systems with 80+ years of pump engineering

🔩 Technical specifications

🔗 Compatibility Guide

Replaces / Cross-References

The Little Giant P115 is documented as a replacement for the following pumps:

Part Number	Manufacturer / Description
006-ST4	Taco — 1/40 HP Stainless Steel Circulator, 3/4″ NPT, 115V
611365	Industry Part Number — Baptismal Pump Application
9523-01	Industry Cross-Reference

Connection Details

• 📍 Suction: 3/4″ FPT (Female Pipe Thread)
• 📍 Discharge: 3/4″ FPT (Female Pipe Thread)
• 📍 Design: Inline circulator — installs directly in plumbing line

⚠️ This pump uses 3/4″ FPT threaded connections, which is different from the barb connections found on most Laing E-10 and Grundfos circ pumps, and different from the 1-1/2″ MBT unions found on Gecko CMHP and Waterway Iron Might pumps. Verify your spa’s plumbing configuration and connection types before ordering.

Cast Iron vs Other Materials

Material	Pump	Advantages
Cast Iron (This Pump)	Little Giant P115	Maximum durability, vibration dampening, heat resistance, proven in HVAC/hydronic
Stainless Steel / Bronze	Little Giant S320PT-20	Corrosion resistance for saltwater/chlorinated, submersible capable
Thermoplastic	Laing E-10, Grundfos 43 Series	Lightweight, corrosion-proof, compact, barb/MBT connections
Thermoplastic	Waterway Iron Might	Higher flow (40 GPM), 48 frame, 1-1/2″ unions

🔩 Alternate Part Numbers & Cross-References

🔧 Parts and fittings for this

Primary Part Numbers

Part Number	Description
P115	Little Giant / Franklin Electric — Primary Part Number

Replaces These Part Numbers

Part Number	Description
006-ST4	Taco — Stainless Steel Circulator Pump
611365	Industry Cross-Reference
9523-01	Industry Cross-Reference

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🛠️ Installation Requirements

Mounting

Requirement	Specification
Installation Type	Inline — mounts directly in plumbing line
Position	Horizontal or vertical per manufacturer instructions
Base	No separate base required — inline design
Access	Sufficient clearance for service and plumbing connections

Plumbing

Connection	Size
Suction	3/4″ FPT
Discharge	3/4″ FPT
Thread Type	Female Pipe Thread (standard NPT)

Installation Notes

⚠️ Wet rotor pumps must have water flowing through the pump during operation. Never run dry — the water acts as the bearing lubricant.

⚠️ 3/4″ FPT connections require matching 3/4″ MPT (Male Pipe Thread) fittings or adapters. Use appropriate thread sealant (Teflon tape or pipe dope) on all threaded connections.

⚠️ Install in a location accessible for service. The wet rotor design is virtually maintenance-free, but access is needed for plumbing inspections and eventual replacement.

⚠️ GFCI protection is required by the National Electrical Code (NEC) for all hot tub, spa, and baptismal pool installations.

⚠️ Cast iron housing is heavier than thermoplastic pumps — ensure plumbing supports the additional weight of the pump.

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🔧 Maintenance Guide

Routine Maintenance

Task	Frequency	Notes
Check for leaks	Monthly	Inspect threaded connections
Verify quiet operation	Monthly	Unusual noise indicates bearing wear
Inspect plumbing connections	Quarterly	Check for corrosion at joints
Check flow rate	Quarterly	Reduced flow indicates system blockage
Verify electrical connections	Annually	Check for loose wiring

Warning Signs — Replace Pump If:

• Unusual noise (grinding, humming, or rattling)
• Reduced or no water flow
• Motor overheating
• Motor fails to start or trips breaker
• Visible corrosion or cracking of cast iron housing
• Water leaking from pump body

Wet Rotor Advantage — NO Seal Maintenance

The Little Giant P115 uses a wet rotor design where the rotor operates directly in the pumped fluid. This eliminates the mechanical shaft seal entirely — there is no seal to leak, wear out, or replace. The water itself lubricates the bearings, providing maintenance-free operation throughout the pump’s service life. This is the same sealless technology used in Taco and Grundfos circulator pumps that have proven decades of reliability in HVAC and hydronic applications.

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🎯 Ideal Applications

Application	Suitability	Notes
♨️ Spa / Hot Tub Circulation	✅ Yes	3/4″ FPT connections, verify flow rate matches system requirements
♨️ Baptismal Pool Circulation	✅ Yes — Documented Application	Sold as baptismal pump (611365)
♨️ Hot Water Recirculation	✅ Yes	Wet rotor design handles hot water
♨️ Replacement Taco 006-ST4	✅ Yes — Direct Replacement	Documented cross-reference
♨️ Hydronic Heating	✅ Yes	Common circulator pump application
🛁 1″ Barb Spa Plumbing	⚠️ Adapters Required	Uses 3/4″ FPT — not barb connections
🛁 1-1/2″ MBT Spa Plumbing	❌ No	Use Gecko CMHP for 1-1/2″ connections
🛁 High-Flow 10+ GPM	⚠️ Verify	Confirm flow rate from manufacturer documentation
🛁 Saltwater Applications	⚠️ Not Recommended	Cast iron may corrode in saltwater — use stainless steel (S320PT-20) instead

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❓ Frequently Asked Questions

Q: What horsepower is this pump? A: 1/40 HP operating at 115V / 60Hz with a draw of just 0.52A. Designed for continuous duty low-flow circulation.

Q: What are the connection sizes? A: Both suction and discharge are 3/4″ FPT (Female Pipe Thread). This is a standard threaded connection — you’ll need 3/4″ MPT fittings or adapters to connect to your plumbing.

Q: Does this pump have a shaft seal? A: No. The P115 uses a wet rotor design that completely eliminates the mechanical shaft seal. The rotor operates directly in the water, which acts as the bearing lubricant. There is no seal to leak, wear out, or replace.

Q: What does this pump replace? A: The P115 is documented as a replacement for the Taco 006-ST4 stainless steel circulator and the baptismal pump model 611365.

Q: Is this pump different from the Laing E-10 or Grundfos circ pumps? A: Yes, significantly. The P115 is a cast iron inline circulator with 3/4″ FPT threaded connections, while the Laing E-10 and Grundfos 43 Series are thermoplastic pumps with barb connections. The P115 is heavier, more traditionally constructed, and uses different connection types. Verify your spa’s plumbing before ordering.

Q: Can I use this in a saltwater spa? A: Cast iron can corrode in saltwater environments. For saltwater applications, the Little Giant S320PT-20 (stainless steel and bronze, part 517100001) is a better choice.

Q: What is the flow rate? A: The flow rate is not independently confirmed for the P115 in available documentation. The Taco 006-ST4 it replaces is rated at 0-10 GPM with 0-9 ft head, but these values should be verified from the manufacturer documentation included with the pump. Contact Parts4Tubs for specific flow rate information.

Q: Why cast iron instead of plastic? A: Cast iron provides superior durability, vibration dampening, and heat resistance compared to thermoplastic housings. It’s the traditional material for hydronic circulators and is proven in decades of HVAC and hot water applications. The trade-off is heavier weight and potential corrosion in aggressive water chemistries (saltwater, highly acidic).

Q: Can I use this for a baptismal pool? A: Yes. The P115 is sold specifically for baptismal pool applications. The hot water capability and continuous duty design make it well-suited for baptismal pool circulation and heating systems.

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

🏆 Why Choose the Little Giant P115

• ✅ Cast Iron Construction — Professional-grade durability that outlasts thermoplastic housings in hot water applications
• ✅ Wet Rotor Design — NO shaft seal to leak, wear, or replace — truly maintenance-free motor operation
• ✅ Ultra-Low Energy — Just 0.52A at 115V for continuous 24/7 operation at minimal cost
• ✅ Standard 3/4″ FPT Connections — Compatible with standard plumbing fittings and adapters
• ✅ Inline Compact Design — Mounts directly in plumbing line with no separate base plate required
• ✅ Proven Circulator Technology — Same wet rotor engineering trusted in millions of HVAC and hydronic installations
• ✅ Direct Taco 006-ST4 Replacement — Drop-in substitute for the widely installed Taco 006 series
• ✅ Baptismal Pool Proven — Documented application in baptismal pool circulation systems
• ✅ Franklin Electric Quality — Backed by a global leader with 80+ years of water system expertise
• ✅ Simple & Reliable — Single-speed, no complex electronics, proven traditional engineering

🤝 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
• ✅ Complete Little Giant pump range in stock
• ✅ Dedicated customer service team

⭐ Summary

The Little Giant P115 is a 1/40 HP cast iron circulation pump featuring wet rotor design with no mechanical shaft seal, operating at just 0.52A on 115V/60Hz. With 3/4″ FPT suction and discharge connections, this inline circulator provides heavy-duty reliability for spa, hot tub, and baptismal pool applications. A direct replacement for the Taco 006-ST4 circulator, the P115 combines proven HVAC-grade circulator technology with the Little Giant / Franklin Electric reputation for quality and dependability. Order from Parts4Tubs today for expert support and fast shipping.

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.

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.