Automatic water pump HITACHI WM-P400XV Inverter 400 watts, 1 inch pipe

     Automatic water pump HITACHI Model WM-P400GX Inverter  (400w.)

The inverter system commands the motor to adjust its operating speed to maintain consistent water pressure at every outlet.

The inverter system, along with the DC motor and advanced technology design, ensures quiet operation throughout use.

Delivers 20% more water volume than conventional pumps thanks to the DC motor system and specially designed pump casing, boosting the water pump's efficiency.

The pressure tank is filled with nitrogen gas and reinforced with a rubber diaphragm, preventing water from coming into direct contact with the tank, thus preventing rust throughout its service life.

Saves up to 40% more energy; the inverter system adjusts the motor's rotation speed to match water usage, reducing unnecessary energy loss.

Saves installation space: the inverter system along with the pressure sensor enables more precise operation and reduces unnecessary parts, making the pump compact in size.

Constant pressure water pumps, or square-tank water pumps, are available to meet every application need from 150-400 watts. Unlike round-tank pumps, square-tank models feature a pressure tank equipped with a rubber diaphragm filled with nitrogen gas, which creates pressure inside the nitrogen tank to help push water out. This means the pump generates pressure immediately every time water is turned on without waiting for water pressure in the pipe to drop to a certain level, providing steady, consistent water pressure at every faucet. They are compact, saving installation space, and feature a square shape with a white cover, gray body, and black base. However, newer models in the XX series now feature a gray cover—developed to be superior in both performance and with significantly quieter operation, allowing them to be installed next to bedrooms without noise disturbance.

Key features of Hitachi water pumps 

- Constant pressure with a specially designed Life-Extending Pressure-stabilized Unit that regulates water flow rate.
- Equipped with a nitrogen pressure tank that ensures steady water pressure without needing gas refills throughout its lifespan.
- All Hitachi water pump models are certified with the Level 5 Energy Efficiency Label and offer maximum efficiency according to industrial standards. 
- Strong, durable motor that prevents rust corrosion, backed by a 5-year motor warranty.
- Brass check valve closes tightly, eliminating air entry into the system; rust-resistant

Motor burnout protection system with up to 3 parts

- Internal motor thermal relay safety to prevent motor burnout, which automatically cuts off motor operation if the temperature exceeds 160°C ±5°C
- External water temp relay safety to prevent motor burnout, which immediately cuts off motor operation automatically if the temperature exceeds 65°C ±5°C
- Pump cover made of special "PPV0" material prevents the spread of fire and self-extinguishes within 10 seconds

Hitachi turbine-type water pump 

In the new models of Hitachi square-tank pumps in the XX series, the Hitachi turbine-type 2-impeller system water pump is the latest innovation from Hitachi. Revolutionizing the domestic water pump industry with full power and zero noise disturbance. Revolutionizing automatic water pumps with turbine technology, Hitachi's latest home water pump innovation provides full performance for increased water volume and extremely quiet operation, creating no disturbance for residents or neighbors. Ideal for urban residences that are typically adjacent to each other. Superior to conventional water pumps in every aspect.

Advantages and differences from conventional models of the Hitachi turbine-type 2-impeller water pump 

- New casing system developed from centrifugal pumps featuring 2 sets of impellers inside, meeting demands for both high power and ultra-quiet operation at noise levels below 49 dB
- Redesigned pump cover made of special "PPV0" material helps prevent the spread of fire
- The motor features a function that spins off foreign objects before entering the motor body to extend its service life.
- Stronger and constant pressure, suitable for large houses with simultaneous water usage at more than 8-9 points

What type of house is a Hitachi constant-pressure water pump suitable for?

Suitable for general homes and commercial buildings requiring constant water pressure, especially homes equipped with water heaters and rain showers, and households with multiple members using water from multiple outlets or showering at the same time. 

What wattage water pump should be used?
1-2 story house with 1-3 residents: 150 watts is sufficient. 
2-story house with 4-5 residents: 200 watts or higher is recommended.
3-story shophouse/townhouse with multiple residents: 300 watts or higher is recommended. 
**However, if you want higher wattage for extra power upfront, that's fine, but keep in mind that higher wattage also means higher electricity consumption. Therefore, matching it appropriately to actual usage is best. 

How to maintain a Hitachi water pump 

1. Observe pump operation, such as whether water pressure flows strong and normally, whether the sound is normal, and whether the pump cuts in and out properly.
2. You should open the cover to check the interior for any leaks.
3. Prevent any leaks inside the house. If leaks are left unattended for a long time, the water pump will work harder and more frequently, overloading the motor unnecessarily and increasing electricity costs.
4. Always close the faucet completely right after use.
5. Check the cleanliness of the water in the water tank to prevent debris, dirt, and sand from entering the pump.
6. Build a sun and rain shelter to extend its service life.

Basic troubleshooting guide for abnormalities in HITACHI square tank pumps

HITACHI square tank water pump making abnormal noise 
Find the source of the noise. In most cases, loud noises come from 3 main points: the water impeller, the cooling fan, or the shaft bearings. 
Water impeller: Mostly caused by foreign objects getting trapped inside the impeller, such as gravel or stones. To fix, use an 8 mm socket or T-wrench to remove all 4 bolts, then remove the cover, clean the impeller thoroughly, and reassemble.
Cooling fan: Common issues include the motor cooling fan becoming loose, degraded, broken, or having small animals or insects inside. Fix by removing and replacing with a new fan blade. 
    1. Use a Phillips screwdriver to loosen the screws securing the cover. 
    2. Use retaining ring pliers to expand and remove the impeller snap ring, then gently pull out the damaged fan blade. 
    3. Then install the new fan blade back into the original position. 
    4. Reassemble the parts.
Shaft bearings: This issue is usually caused by damaged bearings due to degraded waterproof seals, allowing water to enter the bearings and cause rust. The solution is to replace both the seal and bearings. Since this repair is difficult and involves multiple complex steps, contacting a nearby service center is recommended. 

HITACHI water pump running frequently or cycling too often
This problem is usually caused by leaks, either in the water pump itself or within the household plumbing. Here is a simple test method: close the outlet water valve and observe whether the water pump returns to normal. If it stops cycling, it means there is likely a water leak in the home's plumbing system or at water fixtures (such as faucets not closed tightly, leaking, or cracked). However, if the outlet valve is closed and the pump still continues to cycle abnormally, it indicates the issue may be with the pump itself—such as worn or damaged spare parts like a leaking front pump seal, leaking shaft seal, or cracked casing. Fix it by replacing with new spare parts.

HITACHI square tank water pump not working
     1. HITACHI water pump not working due to the thermal cut-off system: The motor overheats beyond the limit, which may be caused by heavy load from a dry water tank, leaks, or continuous running until overheating occurs. The system automatically cuts off power to prevent the motor from burning out. The fix is simply to unplug the pump, wait for the motor to cool down, and then plug it back in for use. 
     2. HITACHI water pump not working due to a stuck or deteriorated pressure switch: If the pump has been used for several years, the pressure switch can stick due to rust. To fix this, turn off the circuit breaker, use a Phillips screwdriver to unscrew the pressure switch cover, and check for any burn marks or short circuits. If none are found, use a brush or spray anti-rust fluid, scrub it with a brush, and press the copper contact points together gently several times until smooth. Wait for it to dry, then turn on the circuit breaker to check if it works. (However, if the pressure switch is still brand new, you can rule out this method as the issue may stem from other causes.)
     3. The Hitachi water pump not working due to no power supply to the pump: To check, use a Phillips screwdriver to loosen the screws and remove the machine cover and condenser cover. Then use a voltage tester screwdriver to touch the wiring terminals connected to the motor, testing multiple points alternately to see if power is supplied. If there is no power coming in, check the wall outlet or circuit breaker again.  
     4. The Hitachi water pump not working due to a degraded, defective, or shorted capacitor:  To check, use a Phillips screwdriver to loosen the screws and remove the machine cover and condenser cover. Then check the capacitor  (the black rectangular component) to see if it is swollen, burned, or abnormal. If abnormal, fix it by replacing it with a new one. 
     5. The Hitachi water pump is not working due to a shorted or burned motor. This problem rarely occurs in modern water pumps today because they have extensive motor protection systems. Motor damage or shorts usually result from heavy overloading of the pump or prolonged use over time. Solution / Inspection: It is recommended to have a technician inspect it thoroughly to be certain, and then resolve it by replacing with a new motor or rewinding the motor, which can be almost as costly as buying a new pump. 

How to install a Hitachi square tank water pump

Water pump installation equipment
- PVC pipe cutter scissors, saw
- No. 13 wrench 
- Pipe wrench
- PVC pipe glue or solvent cement
- Ball valve
- Check valve 
- Tee fitting
- Elbow fitting
- Male straight connector 
- Straight connector size 
- PVC pipe 
- Teflon thread seal tape 

The water pump should be installed with a dual system: using water boosted by the pump, and bypassing the pump directly in case of a power outage or tap water interruption.

- Prepare the area for placing the water tank and the pump; there should be a roof to protect from sun and rain for a longer service life.
- Place the water pump as close to the water tank as possible for maximum efficiency.
- Connect the pipe from the water meter by first shutting off the meter valve, then connect a tee fitting to split the flow into the water tank and directly into the house.
- Run the pipe into the water tank, installing 1 ball valve to shut off the water for maintenance, and properly install the float valve inside the water tank.
- Screw straight threaded adapters into the tank's water outlet and the pump, wrapping Teflon tape clockwise around the threads about 10–15 turns. 
- Connect the pipe to the ball valve properly, then install the pipe line from the water tank to the water pump, with the ball valve positioned between the water tank and the water pump.
- Then connect the water outlet pipe with another ball valve, followed by a tee fitting connecting to the house and the municipal water supply
- Run a pipe from the meter and tank tee to connect to the tee in front of the water pump, with 1 check valve installed in between to prevent backflow when water is drawn from the water pump. 
- Connect the electrical wiring to the water pump while keeping the circuit breaker turned off.
- Open the water valves at the meter and at the tank inlet; wait until the water tank is completely full.
- Open the valve from the water tank to the pump while keeping the outlet valve closed.
- Turn on the water pump's circuit breaker, then wait a moment for the pump to run and then stop. 
- Open the outlet valve leading into the house, then test the pump's operation by opening and closing faucets inside the house. That completes the installation.