To many contractors, direct digital control (ddc) systems are still confusing. It doesn’t matter that they’ve become well established in the last two decades and that manufacturers are making them easier to use than ever before. Many contractors still have lingering doubts — or fears — about getting involved with such complex systems.

But now there’s an easy-to-use controls system from Carrier, which has some contractors waxing enthusiastic. These people are calling the “ComfortID” system a “pleasure to install,” “a true delight,” and “a walk in the park.” When you hear contractors talk like that about a controls system, it’s definitely worth investigating.

Real-Time Control

The new system uses ddc technology, allowing equipment and components to communicate with each other. Sensors placed around the building gather data such as temperature and CO2 levels and send it to microprocessors, which interpret the information and provide a response, such as changing fan speed, outdoor air intake, or damper position.

Due to the constant flow of information from the sensors, the system can immediately respond to changes in temperature and ventilation levels, which helps provide constant indoor comfort, according to the manufacturer. Carrier also says that providing the right amount of air instantly will allow multizone buildings such as schools, health care facilities, office buildings, and the like, to minimize energy and maintenance costs, while providing a healthy environment for tenants.

Mike Haase, owner of West Coast Air Conditioning, Oxnard, CA, put in his first system last December in a 42-zone office building with vav and hot water reheat. The year-and-a-half-old building was experiencing a large amount of failures due to its existing controls system.

The main problem was that the existing controls system wouldn’t “talk” to the Carrier chiller or air handler and didn’t offer the benefit of tighter temperature control, so Haase recommended the ComfortID.

“Everything is now integrated — the chiller, the air handler, and the zones — for maximum comfort level and energy savings,” says Haase.

The building owners have been thrilled with the tighter comfort control of the space. They also appreciate that the system is actually talking to the components, and thus far there hasn’t been any overcooling or underheating. That helps keep the energy consumption down.

Haase notes that the system is also user friendly, allowing the owner to move or add zones. In addition, if the building experiences a failure in one zone, the remaining zones are not affected.

Balancing Made Easier

For Pearse Kelly, project manager with Southern California Air Conditioning Distributors, City of Industry, CA, the main selling point of the control system is its ease of installation and set-up. The problem in many systems is getting the vav systems up, balanced, and operational.

Kelly notes that Carrier has made this easier by isolating a segment of their control software, so it is possible to hand a floppy disk to an air balance specialist who, with his laptop, can communicate with the individual zone controllers and enter parameters such as minimum and maximum cfm, box size, etc.

“In a matter of minutes with this software package, the air balance specialist can give the box a full blessing. Previously, it was a very tedious task of my taking a reading and his measuring the cfm with his hood, then arguing about who’s right. It was messy. Now you can give the whole thing to the air balance guy, and he’s quite happy not to have to drag you around with him. I’m delighted with that feature, from the installer’s point of view,” says Kelly.

As for the actual nuts and bolts of the installation, that too is fairly simple. The system uses a slip-on, direct-coupled type of actuator that you slide over the shaft and zip down with a few screws, says Kelly. That makes it easier to use in retrofit situations. In fact, Kelly is currently working on a standalone application where a customer has several electric vav boxes that are about 20 years old.

“What I’m going to do is remove the old control, toss it out, and slide the ComfortID controller over the damper shaft; then using the existing wiring, the existing transformer, and the existing control valve on the reheat, I’ll hook up the new one. I expect it shouldn’t take more than 30 to 40 minutes, tops, to do each zone individually like that.”

Can it Talk to Other Manufacturers’ Products?

While it is a given that ComfortID will work well with Carrier products, there’s always the question of how it will function with other manufacturers’ components. Kelly notes that the technology is adaptable, and it can be used to control just about anyone else’s equipment. However, he prefers to stay with a single source, if at all possible.

“There are various means for procuring data from chillers on entering and leaving chilled water, condenser water temperatures, and so forth, so the intertie is not so much a technical challenge, maybe, as it used to be.

“However, the advantage of going with a single source is that each piece of equipment is designed specifically to work with the next. The flow of demand information from the zone to the plant that’s producing the heating or cooling is most effective when you use a single vendor that has a whole communicating line of controls,” says Kelly.

Jeff Tomes, installation foreman, West Coast Air Condition-ing, notes that the system can adapt to any current equipment out there. “You can change it and have it operate any type of application. You’re not set with one type of damper you have to use. You can use any of the ones out there.”

So far, nobody interviewed for this story has had any problems with installation, start-up, operation, or maintenance of the new controller. As Haase stresses, “If it wasn’t a good product, we’d tell you.”

After all, these are hvacr contractors.

Publication date: 09/25/2000