HITACHI DT-P300GX Automatic Deep well water pump

        Automatic Water Pump HITACHI Model DT-P300GX (Deep Well)

Automatic water pump for deep well/groundwater Twin Jet automatic water pump for deep wells 

300 W, automatic switch operates according to the opening and closing of water taps. The tank is made of thick steel

extra thick with anti-rust coating. Can be selected for use with well diameters of 2 inches and

4 inches, with built-in Thermal Relay in the motor to prevent motor burnout. Impeller and valve set

made of high quality resin, durable, non-rusting. Suction pipe set of single jet system made of

special brass

Automatic switch operates in synchronization with the opening and closing of water taps

Equipped with a built-in Thermal Relay in the motor to prevent motor burnout

Impeller and valve assembly made of high-quality resin, sturdy and rust-free

Tank made of extra-thick steel with a 3-layer anti-rust coating

Can be selected for use with well diameters of 2 inches and 4 inches

Suction pipe set for single-jet system is made of special brass, rust-free, sturdy, and durable

Tank exterior coated with metallic paint, attractive, durable, and resistant to rapid fading from sunlight

Automatic pressure water pumps, commonly known as round tank water pumps, are among the earliest models that have been with Thai people for a very long time. They operate on the principle of water displacing air to generate pressure inside the pressure tank. Water is drawn into the steel tank to displace the air inside. When water and air are compressed together, the air at the top pushes down, creating a stronger water flow. The advantage is that it can deliver water to high vertical elevations and over long distances. However, the downside is that the water pressure is not constant. A wide range of models is available to meet all application needs, starting from 100 watts up to 500 watts. The unit features a vertical cylindrical design with a white cover and a green tank, along with a pressure tank base that helps reduce moisture issues at installation sites where water may flow past the tank, such as when placed directly on the ground or near laundry areas; the base helps prevent rust on the tank body.

   Let's take a look at the internal materials of the Hitachi water pump

- Pump Head made of POM plastic, featuring excellent pressure resistance
- Casing made of PPE Glass Fiber, highly flexible and with good pressure resistance
- Casing Cover made of brass for durability, strength, and rust-free performance
- Water impeller made of special copper-brass alloy, reducing wear, extending service life, and remaining rust-free, designed with serrated vanes to minimize water turbulence
- Brass check valve: strong, durable, rust-free, and seals tightly when the pump stops operating. No air flows through, helping reduce low water pressure/loss of pressure issues without needing to install an additional check valve. 
- Pressure Switch relocated to the top to avoid drilling into the tank, eliminating air or water leak issues along pinholes that often occur along weld seams.
- Air charger responsible for feeding air according to the round-tank water pump structure ratio: 3 Water : 1 Air.
- Pressure tank formed with Vilin Potash abortion technology, with thick, non-fish-scale weld seams, making leakage much harder to occur, along with an internal rust-proof coating.
- 1 inlet at the top and 3 outlets to make installation easier in cases where the standard outlet is blocked by a wall or faces installation issues. 
- 3-pin plug, convenient to use and safe.

Motor safety features provided in 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 burnouts, automatically cutting off motor operation immediately 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

What type of house is the Hitachi round-tank pump suitable for?

Suitable for general houses, commercial buildings, or pumping water from the ground floor up to a roof storage tank. However, it is not suitable for houses with rain showers and water heaters because uneven water delivery will cause issues: with fluctuating water flow (sometimes high, sometimes low), the water heater delivers consistent heat, so when the flow is low, the water gets too hot, but when the flow is high, the water doesn't heat up in time and stays cold. If you adjust the heater higher, it becomes scalding when the water slows down again. That is the issue that occurs with water heaters if the pump has inconsistent pressure. 

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 occupants should select 200 watts or more.
3-story shophouse/townhouse with multiple residents: 300 watts or higher is recommended. 
**However, if you want higher wattage for extra power, that is fine, but remember that higher wattage consumes more electricity. Therefore, matching it appropriately to your usage is best. 

Water Pump Maintenance Guide 

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.

Basic troubleshooting guide for abnormal symptoms in Hitachi round-tank pumps

  Hitachi round-tank water pump makes abnormal noise: Find the source of the noise. Most noise issues come from 3 main points: water impeller, cooling fan, or 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 round-tank pump pulsating/stuttering
The issue of the pump or water flow pulsating occurs after being used for a period when the pressure inside the tank drops because water replaces too much air, leaving very little space for air. As a result, there isn't enough pressure to push the water out, causing the motor to cycle more frequently. The solution to this problem is to drain the water from inside the tank.

How to fix a pulsating water pump
1. Turn off the power supply completely; unplug it or switch off the water pump breaker.
2. Close both inlet and outlet water valves.
3. Open the drain plug using a slender, flat, or round tool matching the drain plug slot (such as a screwdriver, scissors, or wrench) by turning counterclockwise to loosen it. Water will then begin to flow out gently.
4. Open the priming plug on the pump head by turning it counterclockwise so that water drains out quickly. 
5. Wait until the water flow slows down or drains completely, then tighten both caps securely.
6. Open the water inlet valve, then turn on the power supply (plug in the pump or turn on the breaker).
7. Wait for the water pump to run for a moment until it stops by itself, then open the water outlet valve.
8. Check the operation of the water pump by turning on the water tap to see if the water flows normally. Then close the water tap to check whether the water pump stops running. If everything works normally, troubleshooting is complete. However, if the symptom persists, some spare parts might be damaged or there may be a water leak; contact a technician to inspect it again.

Hitachi round tank pump not working
The problem of a water pump not working mostly has many causes, such as an overheated motor, no power supply, a damaged capacitor, or a shorted motor. Let's introduce basic inspection and troubleshooting methods.
Methods to check why the Hitachi round tank pump is not working are as follows:
1. Hitachi round tank pump not working due to the system cutting off operation
The motor overheats beyond the limit due to heavy operation from an empty water tank, a water leak, or the pump running constantly until the temperature exceeds the limit. The system then cuts off operation to prevent the motor from burning out. The solution is simply to unplug it, wait for the motor to cool down, and then plug it back in to operate. If it still doesn't work,
2. Hitachi round tank pump not working due to a degraded, damaged, or stuck pressure switch
If the pump has been used for several years, the pressure switch can get stuck due to rust as well. To fix this, turn off the breaker, use a Phillips screwdriver to unscrew the pump cover and pressure switch cover. Then check for any burnt or shorted marks. If none, find a brush or spray anti-rust fluid, then brush it clean, press the copper contacts together, tap gently so it moves smoothly. After that, wait for it to dry and turn on the breaker to check if it works (but if the pressure switch is still brand new, you can rule out this method; it may be from other causes).
3. Hitachi water pump not working due to no power supplied to the water pump
To check, use a Phillips screwdriver to unscrew and open the pump cover and capacitor cover. Then use a test pen to touch the wire terminals connected to the motor, checking back and forth at several points to see if power is supplied. If there is no power coming in, check the wall outlet or circuit breaker again.  
4. Hitachi water pump not working due to a degraded, damaged, or shorted capacitor
To check, use a Phillips screwdriver to unscrew the pump cover and capacitor cover, then check the capacitor—the black rectangular piece—to see if it is swollen, burned, or abnormal. If abnormal, fix it by replacing it with a new one. 
5. Hitachi water pump not working due to a shorted or burnt motor
This problem rarely happens in newer water pump models nowadays as they have quite a few motor protection systems. Motor damage or shorts usually occur when the water pump runs excessively hard or from a long service life. For troubleshooting and inspection, it is recommended to have a technician verify it for sure; fix it by replacing the motor with a new one or rewinding the motor, which costs almost as much as buying a new pump.

Water Pump Maintenance Guide 

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.

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 as a dual system (2-way system).

- Prepare the area for placing the water tank and the pump; there should be a roof to protect against 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.