Home Owner

- What is/causes water hammer?

Water hammer is a pressure surge caused by a rapid change of water velocity in a piping system. Water hammer is often accompanied by a sound comparable to a hammer hitting a pipe, hence the name. In water well systems, water hammer is typically caused when

a) the check valve installed in the drop pipe nearest the pump is more than 9 m above the standing water level, or
b) the check valve installed in the drop pipe leaks while the next check valve above holds.

In both situations a partial vacuum is created in the drop pipe. On the next pump start, water moving at very high velocity fills the vacuum and strikes the closed check valve and the stationary water in the pipe above it, causing a pressure surge and hydraulic shock. This shock can split pipes, break joints and damage the pump and/or motor. When discovered, the system should be shut down and the pump installer contacted to correct the problem.


- How can small UP, UPS pumps be serviced?

No service is required. Should the pump fail while under warranty, it will be replaced.


- My circulator is noisy (humming or chattering). Is it normal? What can I do?

  • 1. Air in the system is causing noise. Air must be purged from entire system.
  • 2. Pump may be oversized for system. Remedy is to throttle back valves until noise quiets down, or replace the pump to a proper size.
  • 3. System may be boiling due to an undersized pump. Remedy is to re-size pump for the system
  • 4. Excessive bearing wear (chattering). Pump must be replaced.
  • 5. System may be clogged (old system). A remedy is to clean the system.


- What does it mean when my circulator feels hot to touch?

  • 1. Circulators are typically used to pump hot water, so a warm or even a hot circulator is normal.
  • 2. Pump may be dry running. Check flow.
  • 3. Pump may have locked rotor due to worn bearings or dirty system. Clean or replace pump and clean system.


- Grundfos MAGNA: Is it possible to adjust the set point when the pump runs in automatic?

No, the setpoint is pre adjusted.


- Why is my motor running hot?

Because of modern design and manufacturing techniques, it is typical for many of today's motors to run hotter than those in the past. In fact, it is not uncommon for the surface temperatures of some newer motors to reach as high as 90°C (194°F) while maintaining and even exceeding the life of motors made in the past.

This means that a "hot" motor is not necessarily an indication that something is wrong. However, if the motor in your pump application seems to be running uncharacteristically hot, there are several situations that may be causing this condition:

  • Electrical: Under or over voltage, unbalanced three-phase power, and a loss of insulation resistance;
  • Environmental: High ambient temperatures, lack of ventilation, and high altitudes (thin air);
  • Mechanical: Excessive cycling, too low or too high a flow rate, high rotating resistance by a damaged pump, high viscosity or specific gravity liquid, or obstruction in the pump.


- Where can I find instructions of installation and operation for a pump/device?

The Installation & Operating instructions (I&O) is enclosed in the pump/device box. They can also be located on the Grundfos Product Center.


- Where can I find troubleshooting information for my Grundfos Product?

The Installation and Operating instructions (I&O) that was supplied with your Grundfos product is an excellent resource for troubleshooting information.

The I&O explains proper installation, operation and maintenance procedures and also contains a troubleshooting section that covers common application problems.

If after you have reviewed the I&O and still need help, please go back to your original point of sale.