Design and Construction Standards

Mechanical systems design for installation on the Georgia Southern University campus shall comply with all codes and standards with American Society of Heating Refrigeration and Air Conditioning (ASHRAE) being the primary source and the most stringent governmental codes governing.

The primary interests of the mechanical design shall be the comfort and safety of the building occupants, the efficiency of the system and the accessibility of the equipment for maintenance. The A/E shall balance the economics of first cost verses payback when dealing with concerns of energy efficiency.

Environmental issues are a tremendous concern to Georgia Southern University. New laws and standards have suddenly created new concerns for HVAC engineers and technicians. Of primary concern to Georgia Southern ARE the CFC issues and the Indoor Air Quality Standards. Georgia Southern makes every attempt to use refrigerants that are proven and are not being phased out in the near future or require the use of extensive safety devices.

Prior to schematic design the engineer shall provide to Georgia Southern at least three mechanical alternates with an analysis of each including cost and the engineers preferred opinion. Georgia Southern shall review the recommendation and inform the engineer which system the University prefers.

The engineer's design of the mechanical rooms shall provide adequate accessible space for repair and or replacement of equipment without having to damage and or remove a portion of the wall sections. It is too often the practice to limit space in the mechanical rooms thus making it extremely difficult to properly maintain or replace the equipment. Water chillers and boilers generally require the most space.

Equipment such as air handlers, pumps, and other types of mechanical equipment located in attic, above floor, or on roofs shall have adequate walkway systems properly designed to support the loads of maintenance personnel and equipment. It shall be installed in such a manner so that access is not blocked by conduit, sprinkler or drain piping.

Roof mounted equipment shall be raised an adequate amount of space, a minimum of 16 inches, to permit roof repair and or replacement without having to move or alter the mechanical equipment. Walk pads or walkways shall be provided to protect the roof membrane from damage from the point of roof access to and around the equipment.

All facilities shall have roof hatches and exterior access to a mechanical or service room to prevent disruption of the building occupants during equipment services.

Facilities with elevators shall have an elevator access to the roof for service. The elevator (either passenger or service type) shall have adequate cab space and capacity to raise or lower any piece of equipment with a maintenance person.

The following list of mechanical items shall serve as a guide to the A/E:

Chiller manufacturers must provide noise criteria for their machine. The noise level shall be tolerable (less than 90 db) at all loads on the chiller. Where large variations in load are anticipated in the facility, i.e. - sports facilities, auditoriums, classroom building, etc, redundant chillers, either multiple or staged units shall be used in lieu of a single large machine. Chillers shall have a digital, diagnostic front-end controller with an LED, non-coded, English display. The chiller controls shall be compatible with Johnson Controls Metasys energy management system.

Chillers shall have a hot gas by-pass installed to assist in running at low loads. Chiller refrigerant must be CFC environmentally friendly, use only R-134A or latest variation. R-22 AND R-123 shall not be used.

The breathing devices provided in the chiller rooms should be escape breathing devices rather than self-contained devices.

Preferred Mfg.: York, Carrier, Trane

The heating system and domestic hot water system shall be separated into two systems. The building heating system shall consist of modular staging boilers. These modular boilers shall be operated on a demand load basis, where all of the boilers will be on only at peak demand and will shut off one at a time as the demand decreases. The modular boilers will have two stage, or more, firing.

The domestic hot water heater shall be a modular unit with a circulating pump to maintain 120 o F maximum at the discharge tap. The reserve storage and method of dispensing this domestic water shall be the responsibility of the engineer.

The use of high temperature steam boiler and secondary heat exchangers is strongly discouraged.

Preferred Mfg.: Raypak, Teledyne Laars, A. O. Smith, Lockinvan

Closed loop type cooling towers are preferred over open towers for condenser water cooling. This will permit the chiller to be shut down and the cooling tower to operate as the chilling source during winter days when the outdoor air temperature is 50 degrees and lower. A bypass system shall be installed so that the chilled water can be diverted past the chiller to the closed loop cooling tower.

Plate heat exchangers with an open cooling tower is discouraged.

Preferred Mfg.: Marley, Baltimore Air Coil

Air handling units shall be industrial grade construction and have positively sloped drain pans and ready access to all components for adjustment and cleaning. The units will also have filter manometers and magnehelic gages to increase access to the full unit.

Preferred Mfg.: Trane, Carrier, York, International

Pumps shall be a maximum of 1750 RPM using high efficiency electric motors and have the following minimum pump efficiencies: In-line must be at 55% efficiency and Base Mounted must be at 60%.

Preferred Mfg.: Raypak, Teledyne Laars, A. O. Smith, Lockinvan

Hydronic reheat systems are preferred. Electric heat strips will be used minimally. Reheat coils should be used only when needed for dehumidifying applications or on large systems with multiple offices or classrooms.

Preferred Mfg.: Redd-I-Heat

Georgia Southern approves the use of variable frequency drives, where applicable and financially justifiable. It is preferred that variable frequency drives be used to control variable air flow in Variable Air Volume systems.

Preferred Mfg.: Square D, Cutler-Hammer, Emerson

Floor mounted or vertical mounted fan coil units are preferred. Overhead fan coil units should be used only when there is no alternative and then with the consent of Physical Plant. All units shall have positively sloped drain pans and ready access to all components for maintenance operations such as adjustment, cleaning and filter changes.

Where multiple fan coil units are to be installed, isolation valves shall be installed in such that single or several units can be isolated from the system without having to shut down the entire system or an entire wing to make repairs to one unit.

All Fan coil diffusers shall be metallic.