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Variable Frequency Drives (VFDs) and Commercial HVAC Cooling Trends

Variable Frequency DrivesEnergy efficiency is the goal of most commercial building owners and facility managers. Not only is an efficient building more comfortable, but efficient buildings also help reduce energy use and thus reduce energy costs. And it all starts with the HVAC system, which accounts for more than 40% of total energy use. For this reason, many facility managers put a lot of time and effort into energy management.

Better Energy Management for Commercial Facilities

HVAC systems must be varied in order to maintain desired temperatures and humidity levels in a building, as the need for cold and hot air varies based on internal loads and outside weather temperatures. In the past, this was accomplished by cycling compressor motors on and off and opening and closing dampers based on thermostat settings. However, this approach was incredibly inefficient and even led to shorter equipment life. With Variable Frequency Drives (VFDs), compressor and fan motor speeds can be varied to better meet desired heating, cooling, and humidity levels.

Variable Frequency Drives and Commercial HVAC Cooling Trends

Over the past decade, the implementation of VFDs has led to substantial energy savings, but commercial HVAC contractors can do more.

VFDs Applied to Condenser Fans

More recently, variable frequency drives have been applied to condenser fans to reduce short cycling of compressors during lower outside air temperature conditions. The use of VFDs, in this instance, allows users to isolate a single circuit or stage of the compressor and better maintain the fixed head pressure to avoid short cycling.

By controlling all of the condenser fans of the refrigerant circuits and incorporating floating head pressure control, this takes the VFD application to the next level – allowing the high side refrigerant pressure to vary up and down along with outdoor air temperature in air-cooled or water-cooled chiller systems. Adding floating high pressure control helps save as much as 30% of the total energy consumption of the chiller.

VFDs Applied to Condenser Water Pumps

Similar to the application of variable frequency drives to chilled water pumps, VFDs can be added to condenser water pumps as well. The same controller can be used to control the speed of the cooling tower fan(s) and reset the condenser water temperature. By lowering the condenser water temperature, the lift of the compressor is reduced, lowering energy usage.

These approaches can be added as retrofits to existing chiller plants without replacing HVAC equipment.

Meeting all your HVAC Preventive Maintenance Needs for your Commercial Facilities

With regular HVAC maintenance, your facility’s energy usage can decrease and equipment lifespan is extended. Call on Crockett Facilities Services to protect your bottom line with our range of commercial mechanical services:

  • VFD and VAV replacements
  • RTU and AHU repairs and replacements, including leak repairs and heat exchanger replacements
  • Chiller preventive maintenance
  • Cooling tower replacement
  • Cooling coil replacements

With the Crockett Promise, we’ll take care of all your building operations, giving you peace of mind, so you can focus on running your business.

Contact CFSI to learn more about our HVAC Preventive Maintenance Programs and costs. We can be reached via phone at 202.600.2787, or online via email sales@crockett-facilities.com or online contact form. We’re In This Building Together!

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Sources:

HVAC Trends: Cooling Controls

This entry was posted on Thursday, March 12th, 2015 at . Both comments and pings are currently closed.

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