Commissioning and business development manager at Aus Chill Technical Services Pty Ltd, David Byrne, explains how VRF/VRV technology, when correctly applied, can deliver big energy savings and improved building maintenance.
VRF/VRV technology is constantly changing which provides exciting new opportunities for energy reduction and improved building maintenance.
As the market continues to grow we also see many of the same issues effecting different buildings. By understanding the reason behind these issues and the benefits of correct application of the technology available we can start to eliminate the majority of these problems.
It is becoming increasingly common to see upwards of 1000+ FCU’s on large VRF/VRV projects. Systems that generally require individual addressing for each fan coil, condenser and refrigerant port.
There are multiple set up options to configure and propriety control systems that communicate through TCP/IP networks and various protocols. Incorrect setup negatively impacts commissioning times, leads to higher running costs and results in ongoing building control issues which can be difficult to rectify once the building has been handed over.
Temperature sensing is one of the most common setup errors we come across. Issues as simple as selecting the correct sensing point are commonly overlooked. Due to the outside air requirements for commercial buildings both conditioned air and outside air are commonly mixed together.
If this happens at the point the temperature is measured it can result in large swings in temperature and dramatically increase the power usage for the building. If you find the conditioned space temperatures greatly overshooting setpoint during upper and lower extremes of ambient temperature this could be the cause.
Utilising heat pump VRF technology in commercial applications is another challenge. Understanding limitations around auto change over options is important. There are options that can be applied whether it be selecting a master FCU to operate in auto, using an ambient temperature interlock to change mode or various other methods but this is only a band aid approach which can create more problems than it fixes.
The key to selecting the best control strategy is understanding how these systems control in the first place and selecting the correct application. This will help reduce issues with FCU’s going into standby.
By understanding how to integrate transmission line, addressing and TCP/IP networks used for VRF/VRV and proprietary DDC controls into one overall network for use within the building there is the potential to create service tools far more effective than most contractors realise is even possible.
While this doesn’t replace the need for a BMS system it provides onsite technicians the ability to trend far more detailed operation data than a BMS can provide.
On a building with 250 FCU’s we were able to create a service tool which allows 67,964,400 points of operation data to be trended for all units in the building going back 31 days in under 2 hours.
This means instant answers supported with trend graphs for the future servicing of the building. This requires an understanding of IT networking as much as it does refrigeration and air conditioning knowledge.
As commercial HVAC becomes more reliant on digital technology, it also allows greater potential for improvements in reducing energy usage, decreased installation and commissioning times and better maintenance and serviceability.
Many of the issues we commonly see are as easily resolved as flicking a switch. By embracing these changes, we can make simple informed decisions that will improve HVAC efficiency as we move into the future.