Centralized Control Improves HVAC Operational Efficiency
Challenging application required a custom solution
For the inhabitants of a five-story building in New York City, the heating and cooling system had surpassed the point of discomfort. After an extensive remodel and update of the building, the one detail that had been left untouched was the control integration of the HVAC system. The owner of the building located in the Upper East Side was faced with the prospect of a system that operated erratically and inefficiently. At times the air conditioning would come on at the same time as the subfloor heating and humidity levels would vary widely from one area to the next.
The property manager of the building struggled with the multiple systems that needed to be regulated and monitored on a daily basis. The owner soon realized that a dedicated building management system (BMS) would solve many of the issues with the varied air conditioning and heating systems. But controlling and integrating HVAC equipment with a unique proprietary communications protocol would not be possible without a conventional large-scale BMS system. The building, however, was not large enough to have an engineering office with a dedicated BMS terminal and server that most conventional BMS systems require. Conventional BMS equipment also lacks the flexibility to control small boilers and domestic hot water systems. After looking at multiple options, the property manager turned to Advanced Systems Design (ASD), a Milford, Connecticut-based systems integrator.
CUSTOM TURNKEY SOLUTION
ASD was contracted to provide a complete turnkey controls solution package for the New York City townhouse. When engineers and technicians from ASD initially evaluated the building they found new challenges that they would have to address. “Space was all but non-existent for a new control panel and all of the major equipment was already installed and in basic operation. We soon realized that we were going to have to design a compact interconnection solution that would keep the panel as small and compact as possible,” explained John Thompson, president and chief design engineer at ASD.
After reviewing a number of possible solutions for the control systems Thompson and the ASD team narrowed it down to a BACnet/IP fieldbus controller. The extensive range of I/O modules allowed for communication, control, and monitoring of equipment that has no built-in communications to interface with. Thompson said, “A lot of times for projects like the New York townhouse, the various air-handling devices and chiller plants and boiler plants have nothing more than an analog input and/or output for signaling and positioning; they do not have a communication protocol that we can write a program for to communicate with them. With a WAGO BACnet controller, we can take advantage of an extensive mixture of BACnet objects, discrete and analog I/O points to create a custom control system solution.”
CONTROLLER FACILITATES EFFICIENCY AND INTEGRATION
ASD set up a BACnet network that allowed for communications directly with the major HVAC equipment installed. The controller supports the B-BC BACnet device profile according to DIN EN ISO 16484-5. With two dual Internet ports acting as an integrated switch, the fieldbus can be wired in a line topology, eliminating additional network devices, like switches or hubs. “The controller enabled us to set up a BACnet network using gateways that allowed for communication directly with the HVAC equipment already installed,” said Thompson.
One of the other added benefits of using the fieldbus controller as the primary processor to bring in all the I/O points was that ASD was now able to offer the client not only an integrated control system, but also the capability to monitor and program alarms as needed. Thompson noted, “BACnet devices allow you to read various data points and set alarms based on various values that come in over BACnet. We can also then, on the PLC side of the controller, set up our own alarms for the discrete components. With the one controller and the mixture of I/O we are now able to develop our own alarms and monitoring schemes.”
For engineered system designers like ASD, proprietary control and monitoring systems do not always fit the bill. “Designing and custom manufacturing control systems for our clients enables us to come into virtually any project and tailor all our monitoring and data points to what the client requires. With BACnet we don’t have any limitations as far as what signals we can pick up and the type of communication protocols that need to come in to the controls we are tasked with designing,” said Thompson.
ASD’s solution resulted in the total integration of all the HVAC equipment in the New York townhouse. The integration created a control system that operated automatically making multi-stage heating and cooling calls as needed.
Another added benefit was a substantial gain in efficiency. “We changed the boilers from on/off control to full modulating staged control using the outside air temperature as a basis for anticipated heating load. This improved the efficiency and operation of the boilers by 32 percent,” said Thompson. The integration also allowed for faster response time to large temperature swings by enabling multi-stage units to function as designed, bringing in additional heating or cooling as needed, all while maintaining tighter temperature and humidity setpoints determined by the owner.
For more information, visit www.wago.us.
Publication date: 11/23/2015