ASHRAE San Diego September Meeting - Past Presidents' Meeting!
Gas Powered Variable Refrigerant Flow Systems
Due to their high efficiency, Variable Refrigerant Flow (VRF) systems are becoming more and more popular in the US. The 2012 ASHRAE Handbook—HVAC Systems and Equipment includes a new Chapter 18 on VariableRefrigerantFlow Systems. The Federal General Services Administration (GSA) assessed VRF with their Green Proving Ground (GPG) program, and found that VRF systems can achieve 34% and higher HVAC energy cost savings when compared to conventional AC systems. VRF uses refrigerant as the cooling/heating medium, and allows one outdoor condensing unit to be connected to multiple indoor evaporators, each individually controllable by its user, while modulating the amount of refrigerant being sent to each evaporator. By operating at varying speeds, VRF units work only at the needed rate. By being on all the time (even at a reduced rate), humidity is controlled and a higher level of comfort is achieved (in addition to the energy savings).
By using a naturalgas engine to drive the compressors, several additional benefits are achieved:
• High electric bills (including timeofuse charges, demand charges, and critical peak pricing) are reduced, since a gaspowered heat pump only uses 20% of the electricity of an electric unit.
• The “heat” part of the heat pump is greatly enhanced by exchanging the heat from engine exhaust into the refrigerant. Unlike traditional electric heat pumps, gas heat pumps are great heaters.
• Overall environmental impact is reduced.
In addition to talking about the unique features of a gaspowered heat pump, our talk will discuss many of the design considerations when implementing a gaspowered VRF system:
• The need for a Dedicated Outdoor Air System (DOAS) to maintain Indoor Air Quality (and code compliance) on ductless VRF systems
• Proper condensate removal at each terminal
• Proper sizing of line lengths
Presented By
Richard Yardley, PE began work in 1980 and learned industrial controls the old fashioned way: from his father. He learned the importance of exceptional quality, rightsizing solutions, empirical solutions (often things work differently in “the real world” than they do in a textbook), and the value of studying customer’s needs before offering a solution. Rich founded Newmatic Engineering in 2000 to provide energyefficient precision airflow control systems to the state of California (mainly). His emphasis has always been to put the customer’s needs first, in order to provide “best value” solutions to his customers. His focus is on designing and implementing energyefficient solutions that deliver savings far in excess of alternative solutions. He saves millions of kWh of energy annually, and his firmlyheld conviction is that he can make the world a better place on a daily basis by providing continuouslyimproving energyefficiency solutions to His customers.