How to Optimise Pumping Energy and Costs

How much energy do pumps really consume?

Pump energy consumption is directly proportional to the flow rate, the pump head, the efficiency of the pump and the motor. 

In cooling applications, the energy provided to the pump itself and transferred to the water has to be compensated by the chillers. Therefore, pumping energy needs to be paid twice in cooling: at the pump and at the chiller.

  • In heating systems, recent research* demonstrates that pumps represent 1.5 % of the annual energy consumption in buildings such as offices, schools, hospitals. 
  • In cooling systems, electrical pumping costs (constant flow distribution) represent 7 % to 17 % of the annual cooling energy consumption.

* Source: PhD thesis by Caroline Markusson, Chalmers University of Technology, May 2009.

 

How much pumping energy is wasted?

Unbalanced systems typically run with a higher flow than necessary to compensate local underflows. It’s quite common that the distributed flow is 50 % above the design value*, especially during partial load when some valves are open while others are closed. 

The solution is to use pressure independent control valves that limit the design flow. 

Such valves compensate excessive pressure by a built-in differential pressure controller. But, pump energy can be wasted on the pressure independent control valves if the pump head is set higher than needed. 

It is difficult to adjust the pump correctly if installed PIBCVs are not able to measure the flow or the available differential pressure.

Proper balancing and commissioning of a system optimizes the set point of the variable speed pump. Savings on the pump head depend mainly on the flow and pump head. 

(*) Source: Investigation by Costic (French Research and Training Centre in HVAC), published in CFP

Journal April-May 2002.


How to set up the pump with TA-Modulator.

The right adjustment of the pump head is possible on the index valve. Usually the index valve is located:

  • in the place with the lowest available differential pressure
  • at the farthest point from the pump
  • in front of the unit with the highest pressure drop
  • or a combination of all above mentioned criteria

 

The easiest way to find the index valve is to check the hydronic calculation.

 

In general, there are 2 options on how to do it:

  1. By measuring the flow
  2. By measuring the available differential pressure

Adjust design flow on all TA-Modulators (actuators must be fully open). In case the design flow is adjusted by TA-Slider actuator, the control signal has to be set at maximum.

A. Measuring the FLOW

  1. Connect TA-Scope to TA-Modulator identified as index valve – and measure the flow.
  2. Select the requested pressure control characteristics and decrease the pump head to get an underflow on the index valve.
  3. Increase the pump head slowly step-by-step to reach the design flow on the index valve (give a pump enough time to reach the new set point).
  4. Make notes about the set point and selected pressure control characteristic in the balancing protocol.

B. Measuring the AVAILABLE DIFFERENTIAL PRESSURE 

Before measuring, calculate the minimal differential pressure you need between the supply and the return pipe of the index valve. This is usually available in all hydronic software.

  1. Close TA-Modulator by setting to position X.
  2. Open the Red measuring point by 5 mm (Use hexagonal key).
  3. Connect TA-Scope to TA-Modulator and measure the available differential pressure.
  4. Adjust the pump head to reach the requested value.
  5. Make notes about the set point and selected pressure control characteristic in the balancing protocol.

It’s recommended to make some other checks of the flow or the available differential pressure on others valves to make sure that the main pipes are not blocked by dirt or air.

 

Conclusion

A proper pump adjustment can save up to 40 % of the electrical energy and protects the system against noisy operation.

How does TA-Modulator save pumping costs?

 - Protects installation against overflows

The built-in differential pressure controller limits the requested design flow when the actuator is fully open. TA-Modulator provides “automatic hydronic balancing" and protects installations against overflows.


 - Delivers only the amount of energy required

The uniquely shaped EQM characteristic guarantees precise flow control in the whole range of power, especially when the flow is lower than 15 %. This is due to the 6x better stroke control in comparison to linear valves.

Learn more about the new EQM characteristic (link)

 - Enables measurement of flow and available differential pressure

The traditional IMI TA Red and Blue measuring points offer a unique package of measurement and diagnostic possibilities:

  • Direct flow, pressure drop and temperature measurement.
  • The Red measuring point bypasses the built-in differential pressure controller to measure the differential pressure available from the pump. It is used to adjust the pump or diagnose the whole installation when the pipes create a higher resistance than expected.

Speak to an Expert

Fale com os nossos especialistas

Entre em contato com um membro da nossa equipe para saber mais sobre a mais nova válvula modulante à venda no mercado, TA-Modulator

Entre em contato