AquaKing 2 4138 12V Fresh Water Pump | 11.3LPM 55PSI

💧 SHURFLO AQUAKING 2 12V FRESH WATER PUMP – 11.3LPM / 55 PSI

Quiet 4-Chamber Automatic Pressure Pump for Caravans, RVs & Marine Fresh Water Systems

💦 The SHURFLO AquaKing 2 Series 4138 is a high-performance 12V automatic fresh water pressure pump designed for multi-fixture caravan, RV and marine water systems.

Delivering up to 11.3 litres per minute / 3GPM with a 55 PSI shut-off pressure, the AquaKing 2 is designed to comfortably supply systems with up to three outlets such as a shower, galley tap and additional faucet.

Its four-chamber co-moulded diaphragm design provides smooth, quiet water delivery, while the built-in adjustable bypass valve helps prevent rapid pump cycling when only a small amount of water is required.

The result is smoother flow, reduced noise and a system that can operate without requiring a separate accumulator tank in a typical installation.

With self-priming capability to 1.8 metres, dry-run protection, ignition protection, thermal overload protection and corrosion-resistant construction, the AquaKing 2 is built for dependable automatic water delivery in demanding mobile and marine environments.

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⚡ KEY FEATURES

💦 11.3LPM / 3GPM Water Flow
Provides strong fresh water delivery for showers, galley taps and multi-outlet caravan or marine systems.

📈 55 PSI Shut-Off Pressure
Provides strong system pressure for compatible fresh water installations.

🔄 4-Chamber Quad Diaphragm Design
Four-chamber construction helps produce smooth flow and low operating noise.

🚿 Supports Up to 3 Outlets
Designed for multi-fixture installations such as a shower, galley tap and additional faucet.

⚙️ Adjustable Built-In Bypass Valve
Helps control low-flow demand, reduce pulsation and prevent rapid pump cycling.

💨 No Accumulator Tank Normally Required
The internal bypass system is designed to provide smooth operation without requiring a separate accumulator tank in a typical installation.

💧 Self-Priming to 1.8 Metres
Can draw water from a tank positioned below the pump within its stated 1.8m / 6ft vertical priming capability.

🔇 Very Quiet Operation
The quad diaphragm design and bypass system help reduce pump noise and repetitive cycling.

🛡️ Dry-Run Capable
Can run dry for periods without damage if the fresh water supply is temporarily interrupted.

🔥 Ignition Protected
Designed with ignition protection for compatible marine and mobile installations.

🌡️ Thermal Overload Protection
Built-in motor protection helps safeguard the pump if operating temperature becomes excessive.

🔩 1/2" NPT Male Ports
Uses standard 1/2" male NPT threaded pump ports for versatile plumbing integration.

🔧 12mm Hose Fittings Included
Supplied with two straight 12mm / 1/2" barbed hose fittings.

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🚐 DESIGNED FOR COMPLETE CARAVAN & RV WATER SYSTEMS

The AquaKing 2 is designed for systems that need more than a basic single-tap water pump.

Its 11.3LPM flow rate and 55 PSI pressure capability make it suitable for applications such as:

• 🚰 Caravan kitchen / galley taps
• 🚿 Internal showers
• 🚰 Bathroom basins
• 🚿 External showers
• 🚐 RV fresh water systems
• 🏕️ Camper installations
• 🚤 Marine fresh water systems

SHURFLO specifies the pump for multi-fixture installations with up to three outlets.

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💦 11.3LPM / 3GPM FLOW

Maximum Flow: 11.3 Litres Per Minute

Maximum Flow: 3 Gallons Per Minute

This provides substantially greater capacity than small 3–4LPM sink pumps and makes the AquaKing 2 much better suited to shower and multi-outlet applications.

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📈 55 PSI SHUT-OFF PRESSURE

The AquaKing 2 has a stated shut-off pressure of 55 PSI.

This allows the pump to provide strong pressure for compatible caravan, RV and marine fresh water systems.

⚠️ IMPORTANT: Before installing a 55 PSI pump, confirm that all hoses, taps, mixers, filters, water heaters and fittings in the system are rated for the pump's pressure.

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🔄 SMOOTH 4-CHAMBER DIAPHRAGM DESIGN

The AquaKing 2 uses a four-chamber co-moulded diaphragm to produce smooth and consistent water delivery.

The quad design provides several advantages in a mobile water system:

• 💧 Smooth water delivery
• 🔇 Reduced operating noise
• ⚙️ Stable pressure performance
• 🚿 Better multi-fixture operation
• 🔄 Reduced pulsation

It is particularly useful in caravans and boats where pump vibration and cycling can easily be transmitted through cabinetry and floors.

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⚙️ ADJUSTABLE BUILT-IN BYPASS VALVE

The AquaKing 2 incorporates an adjustable internal bypass valve designed to provide smoother operation at low water demand.

When a tap is only partially open, a conventional pressure pump can repeatedly start and stop as pressure rapidly rises and falls.

The bypass helps control this behaviour and can provide:

• 🔄 Reduced rapid cycling
• 💧 Smoother low-flow water delivery
• 🔇 Less repetitive pump noise
• ⚙️ More stable system operation

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💨 NO ACCUMULATOR TANK REQUIRED

Thanks to its internal bypass design, the AquaKing 2 can provide smooth flow without requiring a separate accumulator tank in a typical installation.

This can save space and simplify plumbing inside caravans, RVs and boats.

An accumulator may still be useful in specialised system designs, but it is not stated as necessary for normal pump operation.

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🚿 SUITABLE FOR UP TO THREE OUTLETS

The AquaKing 2 is designed for multi-fixture systems containing up to three water outlets.

A typical arrangement could include:

• 🚰 1 × Galley tap
• 🚿 1 × Shower
• 🚰 1 × Bathroom or additional faucet

If several outlets are opened simultaneously, the pump's available 11.3LPM flow is shared between them.

The number of connected outlets should therefore not be confused with the number that can necessarily operate at full flow at the same time.

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💧 SELF-PRIMING TO 1.8 METRES

The AquaKing 2 can self-prime to approximately 1.8 metres / 6 feet of vertical lift.

This allows greater flexibility in pump placement because the pump does not need to be mounted below the fresh water tank.

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🛡️ DRY-RUN CAPABILITY

The pump can operate dry for periods without damage, providing useful protection if the fresh water tank becomes empty or the inlet temporarily loses water.

⚠️ Dry-run capability is best treated as a protection feature. There is generally no benefit in intentionally operating the pump without water for unnecessary periods.

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🔇 VERY QUIET OPERATION

The AquaKing 2 is designed specifically to provide low-noise operation.

Its quiet performance is supported by:

• 🔄 Four-chamber diaphragm design
• ⚙️ Internal bypass control
• 💧 Reduced rapid cycling
• 🔇 Smooth low-flow operation

Installation quality still plays an important role. Mounting the pump securely and avoiding rigid plumbing immediately against the pump can further reduce transmitted noise.

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🛡️ CORROSION-RESISTANT MOTOR CONSTRUCTION

The AquaKing 2 uses a seamless electro-coated motor casing designed to resist corrosion in demanding mobile and marine environments.

The motor casing and pressure-switch assembly are also sealed to provide additional protection for the pump components.

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🔥 IGNITION & THERMAL PROTECTION

The AquaKing 2 incorporates both ignition protection and thermal overload protection.

Ignition protection is particularly relevant to compatible marine installations, while thermal overload protection helps protect the motor if excessive temperature occurs.

These protections add durability but do not replace correct wiring, fusing, ventilation and installation practices.

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🧩 SANTOPRENE DIAPHRAGM & EPDM VALVES

The pump uses:

• 💧 Santoprene diaphragm
• 🔄 EPDM valves
• 🛡️ EPDM seals

These components form the internal pumping and sealing system of the AquaKing 2.

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🔩 1/2" NPT PORTS WITH 12MM HOSE FITTINGS

The pump uses 1/2" male NPT connection ports.

Two straight 12mm / 1/2" barbed hose fittings are supplied, allowing straightforward integration into compatible caravan, RV or marine water hose systems.

This arrangement also gives installers flexibility if an alternative compatible 1/2" NPT fitting is required for a particular plumbing layout.

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⚡ 12V DC OPERATION

The SHURFLO AquaKing 2 is designed for a 12V DC electrical system.

This makes it suitable for compatible caravan, RV, boat and auxiliary-battery installations.

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📋 TECHNICAL SPECIFICATIONS

Brand: SHURFLO

Series: 4138 AquaKing 2

Product Type: Automatic Fresh Water Pressure Pump

Voltage: 12V DC

Pump Design: Quad / 4-Chamber Diaphragm

Maximum Flow: 11.3LPM / 3GPM

Shut-Off Pressure: 55 PSI

Suitable Outlets: Up to 3

Automatic On-Demand Operation: Yes

Built-In Bypass: Yes – Adjustable

Accumulator Tank Required: No for Typical Operation

Self-Priming: Yes

Maximum Self-Priming Height: 1.8 Metres / 6 Feet

Dry-Run Capability: Yes – For Periods

Diaphragm Material: Santoprene

Valve Material: EPDM

Seal Material: EPDM

Motor Casing: Seamless Electro-Coated Corrosion-Resistant Construction

Pressure Switch: Sealed

Motor Casing: Sealed

Ignition Protection: Yes

Thermal Overload Protection: Yes

Pump Ports: 1/2" Male NPT

Included Fittings: 2 × Straight 12mm / 1/2" Barbed Hose Fittings

Applications: Caravan, RV, Marine & Multi-Fixture Fresh Water Systems

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🔧 INSTALLATION CONSIDERATIONS

• Use with a suitable 12V DC electrical supply
• Mount the pump securely in a protected location
• Keep the inlet line airtight for reliable self-priming
• Use suitable fresh-water-rated hose and fittings
• Use the supplied 12mm hose fittings where appropriate
• Keep inlet plumbing as unrestricted as practical
• Ensure all plumbing components are rated for at least the pump's 55 PSI shut-off pressure
• Confirm hot-water system compatibility before installation
• Use correctly sized electrical cable and fuse protection
• Do not adjust the internal bypass without following the appropriate SHURFLO procedure

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❓ FREQUENTLY ASKED QUESTIONS

Is this a good pump for a caravan with a shower and kitchen sink?

Yes. The AquaKing 2 is specifically designed for multi-fixture applications and can support up to three outlets, making a shower and galley tap a strong application.

Can I run three water outlets from one pump?

Yes. The pump is specified for up to three outlets. When several outlets are open simultaneously, the available flow will be shared between them.

Will it give me good caravan shower pressure?

With up to 11.3LPM flow and a 55 PSI shut-off pressure, it has significantly greater capability than a compact single-outlet water pump. Actual shower performance will depend on the shower head, plumbing, filters and hot-water system.

Will I get the full 11.3LPM at my shower?

Not necessarily. The maximum flow rating is measured under lower system resistance. Actual flow decreases as the pump operates against pressure and plumbing restrictions.

How does the AquaKing 2 compare with the Jabsco PAR-MAX 3?

Both are designed for multi-outlet systems and offer approximately 11.3LPM maximum flow. The AquaKing 2 uses a four-chamber design and has a 55 PSI shut-off pressure, while the standard PAR-MAX 3 information provided lists a three-chamber design with a 40 PSI cut-out. The best choice depends on the pressure rating of your plumbing and the type of water delivery you want.

How does it compare with the Jabsco PAR-MAX 3 HD?

Both use four-chamber pump designs and target higher-pressure applications. The AquaKing 2 is listed at 55 PSI shut-off, while the PAR-MAX 3 HD is listed at 60 PSI. Both provide up to 11.3LPM. Check connection type, pressure requirements and installation details when choosing between them.

Is 55 PSI too much for my caravan plumbing?

It may be for some systems. Before fitting the AquaKing 2, confirm the maximum pressure rating of the hoses, taps, mixers, filters, fittings and hot-water appliances already installed.

Can I use it with a caravan hot-water service?

Potentially, but the hot-water system must be compatible with the pump's pressure. Check the manufacturer's maximum inlet pressure before installing a 55 PSI pump.

Would I need a pressure reducer?

Possibly. If any component in the system is rated below the pump's pressure, a correctly selected pressure-control solution may be required. This depends on the complete plumbing design rather than the pump alone.

Does the pump automatically start when I open a tap?

Yes. It is an automatic pressure pump designed to operate according to water demand and stop once system pressure reaches its shut-off point.

Do I need an accumulator tank?

No accumulator is required for normal operation according to the supplied information. The adjustable internal bypass is designed to reduce pulsation and rapid cycling.

What does the adjustable bypass do?

It allows the pump to handle lower water-flow demand more smoothly rather than repeatedly switching on and off. This can improve low-flow performance and reduce pump noise.

Should I adjust the bypass myself?

Only if adjustment is required and you have the correct SHURFLO setup procedure. Altering the bypass setting without understanding the system can affect pump cycling and pressure behaviour.

Can I mount the pump above the fresh water tank?

Yes, within its stated self-priming capability. It can self-prime up to approximately 1.8 metres / 6 feet vertically.

Does the 1.8 metre rating mean I can only use 1.8 metres of hose?

No. It refers to vertical self-priming lift rather than total hose length. Longer runs may be possible, but additional hose and fittings create restriction and can affect performance.

Can it run dry if my tank runs empty?

Yes. The pump is stated as being capable of running dry for periods without damage, providing useful protection if the water supply is lost.

Can I leave it running dry continuously?

Although it has dry-run capability, unnecessary operation without water should still be avoided. Dry-run ability is best treated as protection against temporary loss of supply.

Is this pump noisy?

The AquaKing 2 is specifically designed for very quiet operation. Its four-chamber diaphragm and adjustable bypass help reduce pulsation and rapid cycling, although the mounting surface and plumbing layout can still affect real-world noise.

What hose size does it suit?

The pump has 1/2" male NPT ports and includes two straight 12mm / 1/2" barbed fittings for compatible hose.

Can I change the supplied hose fittings?

The 1/2" NPT pump ports provide flexibility for using alternative compatible fittings if your plumbing layout requires them. Any replacement fittings must be suitable for the thread, pressure and water application.

Can I run this from a lithium battery?

Yes. The pump is designed for 12V DC operation and can be used with a suitable 12V lithium auxiliary electrical system when correctly wired and fused.

Can I run it from an AGM battery?

Yes. A suitable 12V AGM battery can also power the pump.

How many amps does it use?

A current rating has not been provided here, so it should not be guessed for electrical system design. Confirm the current specification for the exact SHURFLO 4138 model before selecting fuse, cable and switch ratings.

Is it suitable for marine use?

Yes. The AquaKing 2 is designed for marine fresh water applications and includes ignition protection and corrosion-resistant motor construction.

Is the pump waterproof?

The motor and pressure-switch assemblies are described as sealed, but no specific IP rating has been provided. Install the pump in an appropriately protected location rather than assuming it is suitable for unrestricted exposure to water.

Would this be a good replacement for an older caravan water pump?

Potentially. Compare the old pump's voltage, flow, pressure, port arrangement, mounting space and electrical requirements. The most important check when upgrading is whether the existing plumbing and appliances can safely handle the AquaKing 2's 55 PSI shut-off pressure.

When should I choose this instead of a smaller 3.8LPM pump?

Choose the AquaKing 2 if you have a shower, several outlets or want substantially greater water flow. A 3.8LPM pump is more appropriate for a simple single-tap setup where high flow is unnecessary.

What should I check before buying?

Confirm that your system is 12V, make sure 11.3LPM is appropriate for your water usage, check that all plumbing components can handle the 55 PSI shut-off pressure, confirm that the supplied 12mm hose fittings suit your plumbing and verify the current draw, cable size and fuse requirement for the exact pump before installation.

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💧 SMOOTH, QUIET & POWERFUL WATER DELIVERY FOR YOUR 12V SYSTEM

The SHURFLO AquaKing 2 combines strong 11.3LPM flow and 55 PSI pressure capability with a quiet four-chamber diaphragm design and adjustable internal bypass.

With support for up to three outlets, 1.8 metre self-priming capability, dry-run protection, thermal overload protection, ignition protection and included 12mm hose fittings, it is well equipped for complete caravan, RV and marine fresh water systems.

For customers wanting strong shower performance, smooth low-flow operation and reduced pump cycling without adding an accumulator tank, the AquaKing 2 is a highly capable 12V pressure-pump option.