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24V DC Dual Pressure Pump System -Jabsco 28 Litre Dual-Max 7.5


24v DC Dual Pressure Pump system. 20 to 40PSI – Integrated Accumulator Tank – Suits 19mm Hose Fittings

SKU: J20-129-24V Category:
Additional information

28 Litre Dual-Max 7.5 Freshwater Automatic Pressure System.

The 24V DC Dual Pressure Pump System is designed for boats, RV’s, caravans, transportable off-grid homes, etc with multiple water outlets. The 24V DC dual pressure pump system operates automatically. When a tap is opened, the system instantly begins operation to provide an even constant flow from the tank to the tap. Closing the tap automatically stops the system operation.

  • Up to 28 Litres Per Minute flow – serves up to 6 outlets
  • Cut-in Pressure 20 PSI : Cut-out 40 PSI
  • 2 stage dual stage pump system lowers amp draw
  • Ignition protected and thermal overload protection
  • Heavy duty mounted plastic base housing
  • Accumulator tank to reduce pump cycling
  • Includes filters, hoses and 20mm (3/4”) connections
  • Fully electrically wired including waterproof fuse holders
  • Self primes to 1.5 metres (5 feet)

Installation diagram of the Jabsco 28 Litre Dual Max Pressure System




The accumulator tank smoothes water flow and reduces on/off cycling of the pump by lessening the variation in pressure. Even flow of water gives better control of hot water temperature especially noticeable with instantaneous gas water heaters and showers. Reduced on/off cycling reduces noise from the pump, water hammer and gives longer pump life.

Dual Pump System

Under low demand conditions only the primary pump operates delivering up to 14LPM. Amp draw is well below that of other high flow systems under the same conditions.

The accumulator tank capacity is perfectly matched to the primary pump. An additional large accumulator is not required.

Under high demand the secondary pump is activated and flow increases. Under maximum demand total current draw is only 7.5 amps (24v).

The dual pump configuration increases the reliability of the system. Should either of the pumps fail, the remaining pump will continue to function with the capability to supply several outlets.

  • Model: 31670-0094
  • LPM: 28.4
  • Nominal Cut In: 20 psi/1.4 bar
  • Nominal Cut Out: 40 psi/2.8 bar
  • Max Amp Draw: 7.5
  • Pump Fuse: 10
  • Breaker: 10


The system is self-priming and may be located above or below the fresh water tank in a dry location.

If the system has rigid piping, provide a short length of hose between pipe and the pump to avoid noise and vibration. Use stainless steel clamps at both ends of hose. NOTE: Inlet and outlet hose must be minimum 3/4(19 mm) ID reinforced hose. Branch lines to outlets should be no smaller than 3/8(10 mm).

Two inlet strainers have been installed in the Dual Max system to keep debris out of system. Fresh water tank must be vented.

If the system includes a city water inlet, an inlet pressure regulator which reduces pressure to 40 psi or less is required. The Jabsco 44410 Series is recommended.

Avoid any kinks or fittings which could cause excessive restrictions. Remember to periodically clean faucet and pump guard screen.


The Dual Max system should be wired to the power supply through a switch rated for 10 amps (24v).

Turn the system off when not in use for extended periods or when tank is out of water.

The electrical circuit should be protected with an overcurrent protection device in the positive lead. See chart for proper size breaker. Pump circuit should not include any other electrical loads. Orange wire is positive. Black wire is negative.

Select wire size from the following chart. Use total length of wire from electrical source to pump and return. Chart allows for 3% voltage drop. If in doubt, use next larger wire size.

Total Wire Length

  • 0-6m: #16AWG (1.5mm sq)
  • 6-9m: #14AWG (2.5mm sq)
  • 9-12m: #12AWG (4mm sq)
  • 12-18m: #10WG (6mm sq)

If you are not familiar with applicable electrical standards, have the unit installed by a qualified electrician.

A complete list of parts and diagram are available on request.

Dimensions of the Jabsco 28 Litre Dual Max Pressure System

  • Check level of water in tank.
  • Open all taps hot and cold.
  • Switch pump on and wait for hot water tank and water lines to fill.
  • Close each tap as flow becomes steady and free of air, close cold water tap first. Pump should shut off soon after closing last tap.
  • Pump is now ready for automatic operation. It will start when tap is opened and stop when tap is closed.
  • If pump will be inoperative for a considerable length of time, turn off circuit to pump and bleed pressure from system by opening taps.

It is recommended that a relief valve with a setting of no more than 125 psi be installed. Often a relief valve is already installed at the water heater. Check its setting. This will protect the system in case the pressure switch fails.



Accumulator tank pre-charge air pressure should be checked annually. Turn pump circuit off. Open a tap and relieve all system water pressure. Adjust precharge air pressure using an ordinary tire pressure gauge and tire pump. Air inlet valve is located on the end of the accumulator tank. Tank pre-charge pressure should be 10 psi. Close tap and turn pump power on.

After installation, check the voltage at the pump motor.

Voltage should be checked when pump is operating along with all the inside electrical fixtures. Full voltage must be available at the pump motor at all times.


  • Pump Body: Glass Filled Polypropylene
  • Pump Design: Multi-Chamber Diaphragm
  • Suction Lift:  Self-Priming to 5 ft. (1.5 m)
  • Ports: 3/4Hose
  • Motor: Permanent Magnet Type with Thermal Overload Protection
  • Accumulator: Hygienic, impact and pressure resistant Plastic Construction. 1 Litre capacity

3 Years Warranty




3 Years