Domestic water works are drawing air

The new domestic waterworks is connected or the filter of the existing system is cleaned. But now the house water works suddenly draws air. This error must be rectified immediately, since not only the delivery rate is impaired, but also cause damage to the pump. Here are the most common causes when a domestic water works.

Uses of domestic waterworks

Good and quality domestic waterworks have become cheaper and cheaper. In addition there are the many possible uses for a domestic waterworks:

  • Domestic waterworks for service or drinking water
  • the house waterwork in the garden
  • the house waterworks for cistern or well
  • the house waterworks for the pool

An important prerequisite is that the house water system is cool and frost-proof. From this, the installation options for the domestic waterworks are usually very limited. This often results in the cause of the domestic waterworks drawing air.

The most common reason for drawn air: exceeded maximum lengths

Because an important point, which must be taken into account, lies in the maximum delivery heights of the domestic waterworks. It must be distinguished after the promotion of the depth of the pump and the delivery height after the pump. The "suction" of the water is bound to the physical laws of negative pressure.

Suction pumps work with negative pressure

Negative pressure is the range between our ambient pressure (atmospheric overpressure) and zero. Under it begins vacuum. This area of ​​negative pressure can also be transferred to the water pressure. This pressure range corresponds approximately to a 10 m high water column. But now no pump can promote this full 10 m water column (exception submersible pumps).

The efficiency of the pump is also crucial

Because every pump has an efficiency. Even from physical laws, this efficiency must always be less than 100. The efficiency of really good pumps is sufficient to suck in a water column of about 8 m. In addition, cavitation occurs on the impeller. So it collects air around the impeller, the pump draws air.

The construction of the domestic waterworks to identify all weak points

But even if all the conditions are met, it always comes back to air is drawn. But first, the typical structure of a domestic waterworks conveyor system:

  • Delivery line with foot valve
  • Filter (eg sand filter or cartridge filter)
  • Water works
  • Connection of the distribution line

Foot filter and filter

The foot valve ensures that the water stays in the riser. Otherwise you may have to vent the house water system. Likewise, there may be a leak on a pipe connection. In addition, the foot valve is often a sieve that should keep rough dirt from the power system.

If this is partially blocked, the delivery rate can not be fully utilized. All these points can also cause the house water system to draw air. The same applies to an upstream filter. This must also be vented. How to vent a sand filter, we show you here.

Cavitation in the pump of the domestic waterworks

All these possibilities can lead to cavitation on the impeller. In other words: the pump runs dry. But water pumps from many domestic waterworks are not designed for that. The water is needed for lubrication as well as for cooling the pump. But because it can always come back to such an incident that the house water works draws air, we recommend in principle the use of a water pump with dry run protection.

Tips & Tricks

What has to be considered when connecting a house water system, we have described in the linked article in detail for you. Even so, you can avoid mistakes and thus the drawing of air through the house waterworks.

Video Board: Air and Pressure Problem Solve // Domestic Water Pump or Monoblock Pump