Case Study

Defense Contractor - Hudson, NH


This two story building located in Hudson, NH is an engineering and manufacturing facility.

R. L. Shields Associates, Inc. provided application engineering and programming services for the upgrade of the original control system to Direct Digital Controls (DDC). 

The facilities major mechanical systems include:

285 - Water Source Heat Pumps (approx.)
2 - Hot Water Boilers
1 - Cooling Tower

This project began in the late 1980's.  American Auto-Matrix was the chosen controls manufacturer.  The heat pumps were to be controlled using American Auto-Matrix's newest product, SOLO/HX's.  The SOLO/HX's were originally connected to   American Auto-Matrix STAR panels.  The STARs allowed the SOLO/HX's to be globally controlled with regards to setpoints, schedules and to monitor for equipment failure.  The STARS were connected to an American Auto-Matrix SAC3, which acted as the host panel.  The SAC3 allowed multiple users to have access to the STARS and SOLO's.  Color graphics capability was provided by American Auto-Matrix's MouseView software.

This project had several areas that created unique challenges.  Due to high levels of area security and special construction requirements, wire entering and leaving these special areas had to be filtered to assure what happened inside the area stayed there and not leaked to the outside areas.  The RS485 network used to communicate with the SOLO devices was not adaptable to this filtering requirement.   It was decided fiber optic would meet the security requirements since it wouldn't carry the RF signals.   American Auto-Matrix had developed a fiber optic product, although not intended for this specific application.   Their product was checked for compatibility with the existing SOLO network and was found acceptable to use for entering and leaving these secure areas.

The cooling tower was controlled by a SOLO/RX.  Fans and pumps were started and stopped by this controller, and number of temperature readings were accumulated to determine why the cooling tower was not performing to specification.  Following a major tower freeze up due to a power failure, it was determined that although the owners had to make emergency repairs, they would replace the existing tower.  Management was going to replace the tower with the same make and model.   The operators expressed concern over replacing a tower that didn't perform well with a duplicate unit.   R. L. Shields Associates introduced the owners to Mike Miller of Fluid Industrial Products.  He ran a number of calculations and used the historical data to determine what the problem was.  It was  determined that the tower was oversized.   The tower was replaced in the mid 1990's with a correctly sized unit at a substantial savings over the prices that they were being quoted.

Some of the control components have been upgraded since the original installation.   This included upgrading the SAC3 to an American Auto-Matrix SAGE MAX.  This eliminated the need for the STARs.  The SOLO/HX's connect directly to the SAGE MAX.   The graphics software was upgraded to American Auto-Matrix's EtherView.

The project has run relatively maintenance free from a controls standpoint.  It has simplified the day to day monitoring and control of the building's temperature.   The operators are able to monitor the HVAC equipment inside secure areas without getting special clearances to enter the area and causing work in the area to be halted.

For more information on this project, contact:

R. L. Shields Associates, Inc.
27 Wentworth Drive
Bedford, NH 03110
603-472-7431 (Voice)
603-472-7395 (Fax) (E-Mail)

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Copyright R. L. Shields Associates, Inc. All rights reserved.

STAR, SAC3, SOLO/HX, SOLO/RX,  SAGE MAX, MouseView and EtherView are trademarks of American Auto-Matrix, Inc.