Hunt Valley One

Heating, Ventilating and Air Conditioning System

The Hunt Valley One project involved a systemic renovation of a 120,000 sq. ft. existing, occupied office building. Mechanical Engineering & Construction Corporation (MEC²) was the mechanical design/build contractor responsible for the heating and air conditioning system installation and control system coordination with the building control contractor.

The project was a partnership with COPT and Transcend, a performance contractor, the building management, and MEC² to renovate the core heating and cooling system without interruption to tenants in the five-level structure. Design and planning were critical to maintain the desired conditions in the building and each team member had input in the planning process.

The scope of the project consisted of the replacement of two 450 ton centrifugal chillers, associated connection piping, insulation, valves and controls. The chiller mechanical room was brought up to current requirements for refrigerant evacuation and safety alarm per ASHRAE 15. Associated roof-mounted cooling towers were replaced including piping, valves, controls, drains, heat tracing and insulation. The building has a mechanical penthouse which houses four existing boilers which were replaced with (4) 1.5 MBH gas-fired high-efficient condensing boilers. Circulating pumps were added to each boiler creating a primary/secondary heating water system. New flues and direct-vented combustion air were also incorporated. Control valves were added to each section of existing finned tube at the perimeter of the building.

The overall heating, ventilating and air conditioning system serving the building is monitored and controlled by a direct-digital computer-based control system. The control system automatically coordinates the function of all mechanical components to assure economical and reliable operation. The system may be monitored within the building and remotely for failures of equipment or operating criteria outside of pre-set levels.

Challenges to the $900,000 mechanical project were consistent with each phase of the construction. The initial phase was to add new control valves to existing finned tube enclosures in occupied spaces. After scheduling and planning with specific tenants, we had to find a compact control valve that would fit into a tight existing enclosure and find a location on the piping that could support the valve.

The building required that no burning could occur in occupied spaces. We incorporated a small Taco automatic control valve that could also be manually actuated due to control system delays. We also proposed pre-fab on the control valves with piping extensions and, during installation, utilized mechanical compression fittings. We accomplished several weeks worth of work in occupied spaces in a few off-hour evenings.

The second phase of the project was the renovation of the boiler plant in the mechanical penthouse. The piping arrangement in the Penthouse required specific as-built plans. The new control strategy modified the piping arrangement to support primary/secondary flow schematics. To support our demolition of the existing work in concert with the new installation, we produced specific mechanical drawings to direct field personnel.

Coordination of mechanical systems with existing building components for wall penetrations and the reuse of existing flue openings assisted in a quick and accurate installation. We also coordinated a building gas pressure change through BGE service utility division for required consistent gas pressure at the boiler burners.

The third phase of the project was the replacement of the roof-mounted cooling tower and two centrifugal chillers in the first floor mechanical room. The chiller replacement was the most challenging portion of the project and required pre-planning and tight scheduling as well as good communication with suppliers and subcontractors with dedicated site supervision. We had no access to the space for large equipment removal or installation. We provided rental chiller units connected to the system and removed the existing chillers by cutting the chillers into pieces small enough to fit out of a man door. As the new chillers arrived, we coordinated with the manufacturer to have the chillers disassembled and the pieces set into place and we reassembled the components of the chillers (i.e., compressors, evaporator and condenser barrels, starters) in place. The manufacturer performed the start-up services. The mechanical room was then brought up to ASHRAE Standard 15 refrigerant safety requirements.

The associated cooling towers were dimensionally different than the existing units that we were tasked with removing. This was an issue, because the existing towers were mounted on steel grillage specifically designed for those towers. The existing towers were mounted inside a walled enclosure which limited us on our installation options. After considering that our insulated, heat-traced piping connections would be extremely tight, we modified the existing steel grillage to support the new cooling towers in an arrangement that would provide optimal operation and ease of service. We stripped the finish from the existing steel, welded additional supports and vibration isolators into place and rigged the units into place.

The new components we installed added greater efficiency to each of the heating and cooling systems of the building. Along with the new control system, our system upgrades added greater comfort level of the building occupants. The building is more energy efficient, reduces energy costs and provides a better work environment.

This project finished on time and within budget.

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