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HVAC Product/Literature/Software

Boiler control: AERCO

May 7, 2012
KEYWORDS boilers / modbus
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AERCO-050612-body.jpgThe AERCO Control System (ACS) is designed for use with the AERCO gas-fired boiler products — KC 1000, all Benchmark, and Modulex boilers. 

The AERCO Control System (ACS) is a flexible controller designed to maximize energy savings in modular boiler plants. The ACS can stage and coordinate the operations of up to 32 boilers and is uniquely designed to maximize the operating efficiency of condensing equipment capable of unmatched modulation. Eight of these 32 boilers can be designated for domestic heating priority. Another eight boilers may be designated as swing boilers serving domestic hot water and building space heating as demand required. With individual unit turndown as high as 20:1, a five-boiler plant delivers 100:1 system turndown when staged to operate sequentially.

Able to regulate overall plant output with precise accuracy, a boiler plant with ±2°F header temperature variation is assured under normal load conditions. It offers sequential or parallel operation flexibility, 100% control of auxiliary equipment, and user programmable modes of operation that can be changed in the field. The ACS automatically rotates the lead unit to help equalize boiler runtime.

The rugged controller is designed for easy installation with low voltage, twisted pair, shielded wire between the panel and boilers. Fault alarm contacts, automatic system start, two interlock circuits and the ability to start an auxiliary piece of equipment (at both start and 100% load) combine all critical functions of the boiler plant into one reliable control center.


It requires less energy for a group of modulating boilers, each firing at “part load,” to heat a building, than for a single boiler operating at “full fire” to carry the entire workload. To meet building demand, the ACS will employ as many boilers as available, each operating at its lowest (but most efficient) firing rate. Importantly, because the ACS reacts in real-time to changes in the number of boilers available, users can take a unit offline for maintenance at any time or bring on back-up boilers for extremely cold conditions without changes to the ACS. And as individual boilers are added or deleted, the energy delivered is automatically adjusted to prevent fluctuations in the header temperature of the plant.


For facilities that have taken a building-wide approach to energy efficiency, the ACS supports easy integration with BAS or energy management software (EMS) programs via Modbus protocol and RS-232 interface. A standards-based open protocol used throughout the buildings controls market, Modbus integration will enable facility managers to drive all ACS operations from any building control platform. BAS or EMS integration also offers a Modbus communication link to poll up to 35 operating parameters from individual boilers through a single connection to the ACS.

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