Controlling Multiple Modulating Boilers: Control strategies can improve high- and low-mass boiler efficiency

摘要

Most engineers are aware of the increased availability of smaller-sized boilers with modulating burners - often referred to simply as modulating boilers - which open the door to a new level of efficiency for customers with small to mid-size applications. Consequendy, more projects are being specified with multiple modulating boilers, whether to achieve redundancy or increase system efficiency. Problems occur when engineers fail to recognize that, regardless of boiler size, systems with multiple modulating boilers require a different control strategy than single-boiler systems. Sequencing and modulation control are critical, and strategy varies significantly, depending on boiler type. This article will discuss the basic principles that apply to the control of multiple modulating boilers for the purpose of improving system efficiency.