Pump - Constant Speed

Pump:ConstantSpeed

Used in:   Plant and Condenser loops

General

Name

The auto-generated name for the pump.

Type

The type of the variable speed pump is fixed as:

• 2-Constant speed

To change from constant speed to variable speed you most open the parent Plant or Condenser loop dialog and change the Plant loop flow type to 1-Variable flow.

Pump Settings

Rated flow rate

This numeric field contains the pump’s rated volumetric flow rate (in m3/s or gal/min).

Rated pump head

This numeric field contains the pump’s rated head pressure (in Pascals or ftH2O).

Important Note: The default pump head provided by the Plant and Condenser Loop templates is 20,000 Pa. This may be suitable for a small building, but it is important that you enter the correctly sized pump head if you wish to simulate pump energy consumption accurately in your model.

Rated power consumption

This numeric field contains the pump’s rated power consumption (in W). If the user is performing a pressure simulation on the loop in which this pump is found, this value would only be used to estimate pump efficiency. During reported calculations, the pump would use the loop pressure drop and current flow conditions along with efficiency to calculate pump power dynamically.

Motor efficiency

This numeric field contains the pump’s efficiency in decimal form (0 = 0%, 1 = 100%).

Fraction of motor inefficiencies to fluid stream

This is the pump’s fraction of power loss to the fluid.

Pump control type

This is a choice field of

• 1-Continuous or
• 2-Intermittent.

The operation of a constant speed pump is fairly straightforward. If the user designates a constant speed pump that is operating continuously, the pump will run regardless of whether or not there is a load. This may have the net effect of adding heat to the loop if no equipment is turned on. If the pump is constant speed and operates intermittently, the pump will run at its capacity if a load is sensed and will shut off if there is no load on the loop.

Pump - Constant Speed Outputs

HVAC,Average,Pump Electric Power [W]

HVAC,Sum,Pump Electric Consumption [J]

HVAC,Average,Pump Shaft Power [W]

HVAC,Average,Pump Heat To Fluid [W]

HVAC,Sum,Pump Heat To Fluid Energy [J]

HVAC,Average,Pump Outlet Temp [C]

HVAC,Average,Pump Mass Flow Rate [kg/s]

Pump Electric Power [W]

Pump Electric Consumption [J]

These outputs are the electric power input to the pump motor. Consumption is metered on Pumps:Electricity, Electricity:Plant, and Electricity:Facility.

Pump Shaft Power [W]

This is the shaft power delivered from the motor to the pump.

Pump Heat To Fluid [W]

Pump Heat To Fluid Energy [J]

These outputs are the energy added to the fluid as heat. For the current algorithm, this is equal to Pump Shaft Power, because the loops are closed and all energy added to the fluid will ultimately become heat due to friction.

Pump Outlet Temp [C]

Pump Mass Flow Rate [kg/s]

These outputs are the water outlet temperature and mass flow rate.