MBI's BAS becomes DIY - Controls & Sensors

Engineered Systems, August, 2003 by Joanna R. Turpin

And now for something completely different: Armed with a knowledgeable staff and a distaste for retrofit price quotes, one facilities engineer at a Michigan R&D complex opted to design, assemble, and install the new BAS in-house. The air-handling, cooling tower, and graphic interface portions are up and running, but challenges remain. While you shouldn't necessarily try this at home, you can settle for reading about the ambition and achievement of this independent group.

Most facilities managers wouldn't think of designing and installing a BAS themselves. Most likely, they would contact either a consulting engineer or a BAS manufacturer's representative to figure out the type of system needed, then have the system installed by a controls contractor.

But that conventional way of thinking didn't work for Phil Hegge, director of facilities and 'services of MBI (Lansing, MI). MBI is a nonprofit research and development firm that currently occupies a 120,000-sq-ft research laboratory built in 1986. The building had a BAS in place, but it was rather primitive to begin with, and the vendor was not able to provide any reasonable upgrade paths. By 1998, parts were no longer available for the BAS hardware, and it became necessary to look at installing an entirely new system.

The existing BAS vendor, as well as other BAS manufacturers, could only suggest ripping out the entire existing system and replacing it with a new one. Hegge didn't like this idea, mainly due to the exorbitant costs the various vendors said would be required to replace the system. He and his staff decided to look at writing their own algorithms and flow charts and buying the controls directly from a manufacturer not typically involved in the HVAC industry.

The result is an ongoing, do-it-yourself BAS project that is saving MBI a lot of money, while giving the facilities staff more control over most of its HVAC system. But challenges still lie ahead, particularly in regard to equipment manufacturers who are unwilling to provide Hegge with proprietary controls information.

GETTING STARTED

Once Hegge realized a new BAS was needed for MBI, he started looking for a reasonably priced controls system that would work in a lab setting and also offer the ability to customize operation and programming to meet some of MBI's unusual requirements. He also wanted a system that was easily accessible from off site.

Quotes were obtained from several of the major BAS manufacturers, but the prices were much higher than what Hegge was expecting. "Maybe I'm getting old, but I just can't relate to the prices they charge for some of their products," said Hegge. After talking to others using various systems, he also had reservations about getting suitable performance for the money in his laboratory setting, as opposed to a more common office application.

However, instead of giving up, Hegge and his staff decided to look at the BAS from another angle. They had successfully used controls from Opto 22 (Temecula, CA) in MBI's pilot plant, so they decided to try using that manufacturer's products for the building controls retrofit.

[FIGURE 1 OMITTED]

"Opto 22 makes control hardware components and a software package called 'Factory Floor,' but they're not big in the HVAC market," said Hegge. "We used their products here starting in the late 1980s in our pilot plant for process control, and we've done some fairly big projects over the years in biochemical processing using their hardware and software."

Hegge and his staff decided to see what would happen if they came up with algorithms and flow charts for an air handler and hooked it up to the Opto 22 system. "We were surprised at how easy it was," said Hegge. "For each air handler there are four PID (proportional integral, derivative) loops. You start it and stop if, put some safeties in the control charts, and that's pretty much it."

From 2000 to 2002, Hegge and his staff retrofitted the controls on 13 air supply units (each about 25,000 cfm using 100% outside air), approximately 25 exhaust system fans, and a cooling tower, using the Opto 22 control hardware and their in-house programs written in Factory Floor. (Most of the air supply units run as VAV systems and provide cooling, heating, and humidification.)

ONTO PHASE II--AND SOME CHALLENGES

Changing over the air-handling equipment was considered to be Phase I of the project. Once that was finished, Hegge started working on Phase II of the project, which consists of retrofitting, controls in the main mechanical room. This started with work on the flow charts for the air compressor and RO/deionized water systems. He anticipates those systems will be switched over completely this summer.

Retrofitting the controls for the boilers shouldn't be too much of a problem, because the existing BAS has minimal control over them anyway. "Basically we have fail-over control, so if one of the boilers fails, the other boiler will go from 'stand-by' to 'on.' We plan to keep the same scenario with the Opto 22 controls. Due to the limited amount of things we can do with the boilers, we expect the retrofit will be very easy. We plan to finish them up this fall," said Hegge.