Recent Control Developments

Three developments have occurred in on-board control strategies of condensing modulating boilers, including control of a boiler's internal operations and control of and communication with its external systems.

The way in which electronics control a boiler's internal operations is considerably more complex than simply turning on a boiler to meet heating demand. Condensing-boiler controls strive for low inlet-water temperatures, which effect the best burn and highest efficiencies. Specially commissioned electronics monitor inlet-water, outlet-water, flue, system, and, in most cases, outdoor-air temperature. After operational parameters (most of which are field-adjustable) are set, control boards can begin balancing boiler functions. Boiler controls also can read burn cycles; recognize bad firing patterns, such as short cycling; and adjust heating requirements.

Multiple-Boiler Controls

Condensing-boiler electronics have switched from somewhat blind and mechanical control systems to systems that read more, understand consequences, and operate with sensitivity. Controls now look outward to provide better internal management by controlling a boiler's external systems.

Intermittent pump operation, an early example of external boiler control, prompted pumps to shut off during boiler shutdown. This saved energy by reducing electricity consumption and heat loss caused by water flowing through the boiler. As boilers were connected directly to remote controls, the need to control system pumps became apparent.

The most important boiler-control advancement has been the development of built-in multiple-boiler control. Previously, unified multiple-boiler control required a remote-control board or building-management system. With onboard programming, multiple boilers now can be wired together to cascade.

Onboard programming was developed for two reasons: cost and control. A boiler system's overall cost is reduced by eliminating the expense of a separate multiple-boiler control. Three boilers with built-in cascade are cheaper than three boilers and a separate control system. Onboard programming also improves multiple-boiler control. Three similar boilers with built-in cascade provide better control than a remote control that may not be perfectly tuned to the firing characteristics of the boilers, especially modulating boilers.

Future Upgrades

The next electronic update will improve a boiler's ability to communicate with building-management systems, which now are common in commercial installations. Recent technologies include the direct connection of a boiler to a computer. Some of the best control programs have onboard three- or four-character liquid-crystal displays that relay information in display codes. With a boiler's direct connection to a laptop computer, readout information appears in full, clearly understandable words. Instead of scrolling through a boiler's simple display to read several data points, the laptop shows all of the main data points on one page.

Built-in dial-up or Internet capabilities are not far behind. These capabilities assist boiler-supplied computer programming, which shows boiler operation in real time. Although a cable can be run directly from a computer to a boiler if both are in the same room or building, more computer-savvy engineers, designers, and building managers want to look at their boilers from somewhere off site. Further, more installers and plumbing contractors offer maintenance services that would be improved vastly if a boiler could be seen all day, every day.

Conclusion

The boiler industry has made some real advances in design and electronics. New boilers have a great deal of new technology. Make sure to use it. Go shopping to see what control features can be used. Find out about your boiler's control features. It is easy to find features that can be beneficial on your next job.

The next time you design a system, look past what input and output the system needs. A controls professional should be involved early in the project. Questions, such as whether a third-party control is needed or onboard cascade is available, should be answered. If a third-party control system is planned, boiler inputs and outputs should be considered.

A product manager for Lochinvar Corp., David A. George is a 20-year veteran of the boiler industry. He can be reached via e-mail at dgeorge@lochinvar.com.