Condensate Pumps Information

Condensate pump from Armstrong International, Inc.

Condensate pumps are pumps used specifically to collect and transport condensate back into a steam system for reheating and reuse, or to remove unwanted condensate from an HVAC or appliance collection pan. The recovery of condensate from these pumps helps to reduce costs associated with the production of steam. In operation, these pumps tend to run intermittently, switching on once a connected basin or tank has filled with condensate to a certain point.

Types

Types of condensate pumps can be classified by design or by application.

Design

The two fundamental pump designs are dynamic (centrifugal) and positive displacement.

  • Dynamic pumps, and their subtype centrifugal pumps, utilize fluid momentum and velocity to generate pump pressure. Centrifugal pumps which run on electric power are the most commonly used condensate pumps. They enable large amounts of condensate to be recovered for reuse, some even in areas of high pressure.
  • Positive displacement pumps operate using expanding and contracting cavities through which the fluid travels. They provide steady, low capacity flow and high pressure.

Both of these pump types are subject to cavitation which occurs if pressure inside the pump is too low, causing evaporation which affects discharge performance. However, specialized versions of these pumps utilize steam or compressed air as the medium to move condensate, meaning there is no danger of cavitation.

More information on different types of pumps can be found on Engineering360's Pump Types page.

Application

Condensate pump from Liberty Pumps

There are two basic types of condensate pumps based on application: circulation pumps and sump pumps.

  • Circulation pumps close a heating or cooling system loop by returning the condensate from a storage or collection basin back into the system for reuse.

This video provides a 3d simulation of a circulation pump:

Video Credit: GALCO

  • Sump pumps are installed in compartments or areas to remove the unwanted build-up of water.

For more information on pump types classified by application, visit Engineering360's Pump Applications page.

Specifications

The primary specifications to consider when selecting condensate pumps are flowrate, pump head, pressure, horsepower, power rating, outlet diameter, and operating temperature.

  • Flowrate, also called capacity, describes the rate of volume discharge through the pump, typically expressed in gallons per minute (gpm).
  • Head defines the energy supplied to liquid (per unit weight) by the pump. It is expressed as a column height of liquid (either vertical lift or suction), given in feet of head (ft).
  • Pressure describes the operational pressure of the pump. It is usually given in pounds per square inch (psi) or bar.
  • Horsepower indicates the output power of the pump, measured in units of horsepower (hp).
  • Efficiency defines as a percentage the amount of supplied power that does useful work in a pump.

For a more in depth understanding of pump specifications, performance curves, and operation, visit the Pump Flow information page on Engineering360.

Materials

Condensate pump from KSB AG

The base material of a condensate pump is important to consider, since condensate is not pure water. The media may contain dust, microbes, water treatment chemicals, sulfuric acid, or nitric acid based on the application and system. Base materials such as cast iron, plastic, and stainless steel possess different advantages for handling various types of condensate.

  • Plastic may be the least expensive base material, and provides excellent corrosion resistance from acids and various chemicals.
  • Stainless steel alloys provide protection against chemical and rust corrosion, and have higher pressure ratings than most plastics.
  • Cast iron provides excellent strength and abrasion resistance, with high pressure ratings.

For more information on materials and many other pump features, visit Engineering360's Pump Features page.

References

Grainger - Condensate Pumps

TLV - Types of Condensate Recovery Systems

Image Credit:

Armstrong International, Inc. | KSB AG | Liberty Pumps