Page 15 - Climate Control News Magazine August 2019

In Focus
Incorrect setup negatively impacts commissioning times, leads to higher running costs and results in ongoing building control issues which can be difficult to rectify.
Getting the most from VRF/VRV technology
COMMISSIONING AND BUSINESS devel- opment manager at Aus Chill Technical Services Pty Ltd, David Byrne, explains how VRF/VRV tech- nology, when correctly applied, can deliver big en- ergy savings and improved building maintenance.
VRF/VRV technology is constantly changing which provides exciting new opportunities for energy reduction and improved building mainte- nance. 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 applica- tion of the technology available we can start to eliminate the majority of these problems.
It is becoming increasingly common to see up- wards of 1000+ FCU’s on large VRF/VRV pro- jects. Systems that generally require individual addressing for each fan coil, condenser and re- frigerant 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 im- pacts commissioning times, leads to higher run- ning costs and results in ongoing building con- trol issues which can be difficult to rectify once the building has been handed over.
Temperature sensing is one of the most com- mon setup errors we come across. Issues as sim- ple as selecting the correct sensing point are commonly overlooked. Due to the outside air re- quirements for commercial buildings both con- ditioned air and outside air are commonly mixed together. If this happens at the point the temper- ature is measured it can result in large swings in temperature and dramatically increase the pow- er usage for the building. If you find the condi-
tioned space temperatures greatly overshooting setpoint during upper and lower extremes of am- bient temperature this could be the cause.
Utilising heat pump VRF technology in com- mercial applications is another challenge. Under- standing limitations around auto change over op- tions is important. There are options that can be applied whether it be selecting a master FCU to operate in auto, using an ambient temperature in- terlock to change mode or various other methods but this is only a band aid approach which can cre- ate more problems than it fixes. The key to select- ing the best control strategy is understanding how these systems control in the first place and select- ing 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 effec- tive than most contractors realise is even possible.
While this doesn’t replace the need for a BMS sys- tem it provides onsite technicians with 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 sup- ported 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 po- tential for improvements in reducing energy us- age, decreased installation and commissioning times and better maintenance and serviceabili- ty. Many of the issues we commonly see are as easily resolved as flicking a switch. By embracing these changes, we can make simple informed de- cisions that will improve HVAC efficiency as we move into the future. ✺
LEFT: Temperature sensing is a common setup error.
CLIMATE CONTROL NEWS
AUGUST 2019
15