Figure 1. The original control panel is shown here before the retrofit.
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.

"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 it, 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.

The chillers are going to be a problem, and as a result, they will probably be the last part of the HVAC system to receive new controls. The main obstacle is that the chiller manufacturer doesn't want to reveal its proprietary controls information to Hegge. Instead, the manufacturer would like MBI to purchase control upgrades for the chillers and then use its terminal to control them.

Given that this would be an expensive endeavor, Hegge would rather explore other options. "We're going to try to negotiate with them maybe one more time, but pretty much I've gotten a flat-out, 'We just don't provide that information.' It's the same old story - manufacturers are 'open,' but the door is only so far open. They'll go as far as to let us get some of the points off the chiller, but they won't let us get all the points, and they won't let us send commands to it," he said.

So what's a dedicated DIYer to do? Hegge said they still have several options. First, they could just live with a minimal amount of chiller control (e.g., start and stop) and forego obtaining a lot of the information they receive now. Another option is to try and hack into the manufacturer's protocol and figure out how it works. A third alternative is to possibly pay the manufacturer to upgrade the controls and use that interface and just have a separate system for the chillers. But that would be a pain, Hegge said.

"We do have another alternative. We've talked to one of the other chiller manufacturers about retrofitting controls onto our existing chillers, and that would let us talk to their controls. The best is if our chiller manufacturer would finally condescend and let us talk to our chillers," he said.

The final ending to the chiller controls saga probably won't be known for another six to 12 months.

Figures 2. Phil Hegge said they "pulled the guts out of all the existing control panels and made up our own new panels with the Opto controllers and the input hardware on it."

Reusing What's There

One of the nicest parts of the retrofit is that almost all of the wiring, sensors, and transducers from the existing BAS were reused. Only the temperature sensors needed to be changed. That's because the typical BAS uses 1,000-ohm RTD temperature sensors, and Hegge wanted to switch over to 100-ohm RTD sensors, which are more of a process industry standard. A wire had to be run out to each air handler to change those sensors, but otherwise, everything from the old system was reused.

"We actually didn't have to run that much wire, but we did run a new BUS data link throughout the building. Then we pulled the guts out of all the existing control panels and made up our own new panels with the Opto controllers and the input hardware on it," said Hegge. "Then we just tied in the existing wire that went out to the field hardware."

Believe it or not, the whole retrofit was done in-house with no outside help from consulting engineers, systems integrators, or manufacturers' representatives. Hegge said that he and his staff have worked on the BAS in piecemeal fashion over the last three years, whenever they didn't have more important work to do in the pilot plant.

"It's been a lot of work," noted Hegge. "I think the biggest challenge is that no one has done any extensive HVAC control with Opto 22, so we've had to sit down and work through all of it. Taking into account all the possible operating conditions and problems requires a lot of thought."

In addition, Hegge and his staff had to create their own graphics and display screens with the Opto 22 software package. The package comes in two pieces, the control flow charting module and the display module. The graphics can be static or animated, or anywhere in between.

"We've made our own displays. Clearly, they're not as fancy or as finished looking as what you'd see on some of the major manufacturers' packages, but they show the vital information, and my guys seem to be happy with it," said Hegge.

Indeed, several MBI staff members are becoming very familiar with the software, and Hegge anticipates maintaining the new system without outside help. He says the Opto 22 hardware also comes with excellent warranties. "The warranty on the Opto 22 components is fantastic compared to BAS manufacturers. The input hardware is guaranteed for life, and unless you abuse it, Opto will give you new hardware or fix them for you."

Opto 22 is a distributed controls system, so there is a main controller and smaller field controllers. Under the warranty, the main head controllers can all be replaced at half the cost of a new controller. Hegge estimates it works out to either $300 or $800 to replace the controllers, which is a fraction of what other manufacturers were telling him they would cost.

Best of all, said Hegge, they've saved "a ton" of money by doing the retrofit themselves. "I've spent less every year so far on the retrofit than what one manufacturer was quoting us as a cost for maintenance on their new system. That would've been a $30,000 to $40,000 maintenance agreement."

Doing a BAS retrofit internally is a difficult job, and the challenges for Hegge and his staff aren't over yet. "In addition to coming up with the algorithms that met all the criteria we had set for operation, installation was also a challenge. As with most buildings, our maintenance staff is behind in maintenance and calibration. This meant that as each air supply unit was brought on line all of the hardware needed to be calibrated and checked for proper operation," noted Hegge.

Regardless of the challenges of designing and installing his own BAS, Hegge wouldn't have done it any other way. Once he figures out how he's going to control his chillers, Hegge plans to experiment in one of the labs, retrofitting all the fume hood controls and lab pressurization using the Opto 22 system.

Looks like this DIY pioneer will be keeping himself busy for sometime to come. ES