When Good Systems Have Obsolete Controls

Today’s building engineer has plenty of retrofit control options, even in cases in which the budget is tight. Maybe a building has a sound HVAC system but an existing pneumatic control system (these controllers still comprise a huge segment of the building marketplace). To the facility engineer in this building, it must seem as if everyone else is monitoring his or her building with smart devices, while he still is staring at 0-30 psi gauges to see if dampers and valves are opening. What can be done to help this poor soul?

If we focus solely on buildings with pneumatic controls and assume air-handling-unit integrity is secure, the retrofit question comes down to, “How in love are you with the air compressor?”

If the system’s air compressor provides a clean, dry source of air, a hybrid conversion might be the best option. Replace the existing pneumatic receiver controller hardware with a programmable direct-digital-control (DDC) device and convert the existing sensors to a nickel- or platinum-electronic type. This option allows re-use of the legacy valve and damper actuators by introducing an electro-pneumatic transducer. The transducer converts the DDC input signals into pneumatic output for the continued operation of the pneumatic actuators.

On the other hand, if the budget goes beyond first-cost and allows for removal of the air compressor, consider the (preferred) option of wholesale secondary control system replacement. This will introduce new DDC valves, actuators, and sensors that communicate seamlessly on a communication bus. It also positions the facility for smart device and/or computer terminal access.

I don’t know about you, but my experience shows that very few of the “Nintendo generation” understand pneumatic controls. Therefore, a hybrid conversion (option number 1) might create a maintenance headache, and perhaps cause “turf wars” between pneumatic and DDC staff. Proper training and commissioning, however, will overcome this hassle.

There is one environment where pneumatic controls might still be considered a preference: buildings where chemical vapors are present become a logical application for pneumatic controls because of their inherently explosion-proof characteristic. The DDC world manufactures plenty of explosion proof enclosures, but at what cost and at what angst to the safety department?

Thousands of companies have participated in this new world of building control. “Coopetition” is part of the mainstream and hardware/software/driver technology is being shared among former competitors. When products are compatible they integrate more easily. And the vast number of “Nintendo kids” in our profession more easily relate to computerized technology. Keep this in mind as you purge the air from those pneumatic controls.

Richard A. “Dick” Starr, LEED AP, is CEO and president of the Enterprise Corporation (also known as Enterprise HVAC Service & Control). The company is a design/build/maintain contractor located in the Cleveland, OH area. Enterprise is a Linc Service Contractor, Tridium Systems Integrator, and NEBB certified air/water balance agency. Starr also sits on the national boards of both the Mechanical Contractors Association of America (MCAA) and the Mechanical Service Contractors of America (MSCA). Enterprise HVAC Service & Control was selected as Contracting Business magazine’s 2011 Commercial Contractor of the Year. For more information, visit www.enterprisehvac.com.

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