Sometimes it is necessary to artificially increase the water pressure in the pipeline by using pressurizing pumps , when the pressure exerted by the water column from the tank to the appliance is insufficient, or when there is a negative slope that eliminates the effects of the gravity; This is particularly important at the entrance of water heaters or irrigation hoses.

In this note we will see ten characteristics and secrets that every plumber (and user) must know about these pumps.

Pressurizing pumps: what every plumber should know about them


1. Calculate the maximum and minimum pressure

Artifacts such as water heaters, purifiers, boilers and others require working in a range of acceptable pressures; Just as low pressure prevents proper operation and can cause failures and breakdowns, excess pressure can be equally harmful and even dangerous.

Check the minimum and maximum service pressure in the pressurized devices, and choose those pressurizing pumps that guarantee a service pressure above the minimum but at least 10% below the maximum.

2. Know the direction of water circulation

The presurizadoras pumps must be installed according to the flow arrow indicator; This should always be oriented in a completely vertical direction and pointing up.

Just as it is important to respect the direction of water circulation, it is necessary that the pump is installed in a position that does not impair the operation of the pressurizing chamber.

3. Know the correct installation procedure

  • Always work with the pump disconnected from electrical power.
  • Clean the water tank, install a filter at the outlet of the water tank and verify that there are no leaks or air inlets on the way down.
  • If possible, install a stopcock above the discharge of the pump, and immediately afterwards a check valve to prevent the backflow of water.
  • Use threaded joints for the check valve and stopcock. At other points, try using thermofusion or welding .
  • Verify that the joints between pipes of different materials do not produce galvanic corrosion (an example of this is the union of bronze or copper pipes with others of galvanized iron).
  • Perform a manual purge before operating the pressurizing pumps (see point 8).
  • 4. Place the pump before the appliances
  • Both to pressurize a heater or boiler and to feed the toilets of a bathroom or other passive devices, it is important to remember that the pump must always be before in the hydraulic circuit, since, if air enters the circuit, it is preferable that arrive first at the pump (which has the ability to self-purge whenever there is positive pressure at the inlet).

5. Always work with check valves

The check valves work analogously to the diodes in an electrical circuit, they allow the passage of water only in one direction.

When placed correctly after the discharge of the pump, these valves prevent the return of the water column, thus ensuring that the pump always works properly, even when some air is filtered into the circuit.

These valves should be replaced once every two years or so.

6. Always use the automatic mode

Pressurizing pumps are ready to shut down in case there is zero or negative pressure at the inlet; this as long as they are running automatically. In manual mode the pump will continue to work even if there is no water in the pipe, with the consequent risk of overheating.

7. Make sure the electrical installation is completely waterproof

As important as the installation of the pump itself is the installation of the electrical control panel . It must be located in a sector away from the pressurizing pumps and must have an adequate degree of sealing (at least it must comply with a degree of protection or IP 55).

Another fundamental aspect is the safety of the installation. This must have a sensitive differential switch (circuit breaker) at 30 mA, plus a bipolar thermal key. It is also necessary that the installation has its proper grounding, correctly measured and functional.

The power cable between the pump and the board must be of the workshop type , with triple insulation and grounding cable.

It is especially important that the board is located in a place where the water does not reach to wet it under any circumstance, and must also be easily accessible, even if the area of ​​the pumps is flooded.

8. Know how to properly purge


  1. To perform this operation, first interrupt the power supply of the pump (by cutting the circuit breaker and the thermal keys on the board). Make sure the pump receives no electrical voltage at all.
  2. Close the stopcock above the discharge (outlet) of the pump, so that the water column is not lost upstream.
  3. Remove the drain plug (usually located next to the pump drum) using a fixed wrench of the same size, or a properly adjusted parrot beak key if you do not have another more suitable tool .
  4. Using a thick flathead screwdriver , rotate the pump shaft until water begins to flow through the hole in the drain plug.
  5. Once all the air contained in the downstream pipe has been removed, replace the cap and securely secure it.
  6. Open the stopcock above the pump discharge.
  7. Open a spout tap up and run the pump briefly in manual mode, until the air that has been trapped upstream is removed. Turn off the pump and bring it to the automatic speed position.


9. Check the installation frequently

The review procedure should be routine, once every fifteen days for example, and should not take more than a few minutes.

Start by observing the pump inlet and outlet joints. Inspect them while the pump is running. Note that there are no losses; even a small occasional droplet could cause air to enter the system.

Normally the threaded joints are sealed with Teflon tape , although sometimes lithium paste is used. Avoid using both at the same time, as they are not redundant with each other and the litargirio paste will end up damaging Teflon. The recommended is the Teflon tape.

Then check the pipe upstream, verifying that there are no losses, and that the joints do not present the same problem as before.

Check the downstream spout to find possible leaks or cracks. If there is any stopcock, make sure it is completely open for the branch that feeds the pump.

Visually check the condition of the pump power cable. It must be dry and undamaged. The insulation should look healthy, without drying out.

10. What to do in case of leaks or constants turned off due to the presence of air

Turn off the pump immediately. If you carried out several purging processes and still keep entering the pump, it is necessary to perform maintenance on the water inlet pipe, since upstream the check valve prevents the return of water or air.