The Digi-ACC is a control kit for air-cooled chiller systems.  It reduces energy consumption (kWh) by optimizing and coordinating the system chiller and pumps.

  • Retrofit control kit for air-cooled chiller system
  • Optimizes the operation of the air-cooled chillers
  • Upgrade of the existing pump system(s) into a true variable flow system

Get in touch with us if you are ready to save on peak demand and consumption!

Click on the links below for more information about the Digi-ACC:


Digi-ACC Applications


  • 20 tons up to 500 tons each
  • Two chillers – each chiller has two or more compressors
  • One chiller – two compressors with or without a sliding valve
  • One chiller – four or more compressors

Pumping System:

  • Primary only, constant water flow with bypass
  • Primary only, variable water flow
  • Primary-secondary
  • With or without a backup pump


  • BAS or standalone control

Digi-ACC Features

  • Chilled sequencing optimization
  • Primary/secondary pump speed optimization
  • Optimal chilled water temperature reset
  • Reduced pump power at partial loads
  • Integrates with the existing chiller controller(s) and BAS
  • Remote enable and remote temperature reset are available from the existing chiller controller
  • Demand limiting function

What Benefits Can I Expect If My Building is Equipped with a DIGI-ACC?

  • Integration of the operation of the pump and chiller system thus providing a smooth and  stable chilled water supply
  • Reduces:
    • Chiller energy consumption by 10 – 40%
    • Pump electrical energy consumption by 30 – 70%
    • Compressor hunting (thus extending the lifespan of the chiller)
    • Peak demand
    • O&M costs


How does the Digi-ACC save energy?

  • Sequenced chillers maximize the utilization of the available evaporators and condensers
  • The chilled water temperature reset is based on the measured building load
  • Measuring the pump flow and speed ensures that the pumps run at the most efficient point on the pump curve
  • Compressors are at partial speed during partial load conditions and thus improve the efficiency of the compressor

Does the Digi-ACC modulate the compressor speed?

  • Yes, when there is one chiller with up to two compressors

Does the Digi-ACC control the staging of the compressors?

  • Indirectly.  The compressors are staged by dynamically resetting the chilled water temperature

Does the pumps existing VFDs need to be replaced?

  • The VFD must output the power and speed signals to the Digi-ACC as an analog signal

How does the Digi-ACC interact with existing chiller controller or BAS system?

  • The Digi-ACC controller sits between the existing BAS and Chiller controllers



Where is the Digi-ACC mounted?

  • Mechanical room, chiller controller cabinet or, outside within a NEMA3R enclosure
  • VFD for pumps can be mounted next to the pumps (either inside or outside of the building), or inside the mechanical room at close proximity of the pumps

Install time for the Digi-ACC unit?

  • 5 hours

What is the typical energy savings?

  • 1500kWh – 2200 kWh/ton

What is Digi-ACC’s warranty policy?

  • One year parts warranty on Digi-ACC

Efficiency Tree™

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