Building History and Use
The Union County Agricultural Center at 18000 State Route 4 in Marysville, OH, serves as a hub for county operations, community programming, and agricultural services for Union County residents. Managed under the Union County Commissioners, the facility supports a broad range of daily functions that require consistent, reliable climate control year-round.
Over time, the building’s existing HVAC infrastructure had reached the end of its useful life. The water source heat pumps were aging out of peak performance, the existing boilers had exceeded their operational lifespan, and a poorly sealed plenum was allowing unconditioned air to mix with return air to terminal units, creating performance issues during peak heating and cooling seasons. The combination of declining system reliability and rising operating costs made a comprehensive HVAC upgrade both necessary and timely.
Why Geothermal?
The project scope, led by Trane, called for a full upgrade of the facility’s HVAC infrastructure, including new high-efficiency condensing boilers, a dedicated outdoor air system, and replacement water source heat pumps. At the center of the mechanical strategy was the replacement of the existing fluid cooler with a geothermal well system, which positions the facility for significantly improved efficiency and lower long-term operating costs.
Darcy was brought in through the partnership with Trane to design and install the geothermal well system. The groundwater-enabled approach delivers the thermal capacity the building’s water source heat pump loop requires, with a compact above-grade footprint that fits within the constraints of the existing site. The upgraded Trane cloud-based control system integrates the geothermal system alongside the new boiler plant and heat pumps as a unified, connected solution, also linking the facility to other county buildings for centralized oversight.
Design and Construction
The geothermal system features a convertible well design: a test well is drilled and evaluated first, then converted directly into a permanent production well upon confirmation of aquifer performance. This approach reduces redundant drilling, minimizes site disruption, and ensures the final system is sized accurately to the site’s actual subsurface conditions before additional wells are committed.
Moody’s of Dayton handled drilling for the project, bringing local expertise and knowledge of Ohio’s subsurface geology to support the installation. The geothermal system ties into the existing water source heat pump piping loop at the point where the fluid cooler was previously connected, allowing the retrofit to integrate cleanly with the building’s existing distribution infrastructure.
The full project represents one of the more comprehensive HVAC retrofits in the Darcy portfolio, combining geothermal well installation with new boiler plant equipment, a dedicated outdoor air unit, and a fully upgraded building controls platform, all delivered through a coordinated partnership with Trane.
A First for Ohio, and a Model for What’s Next
The Union County Agricultural Center marks Darcy’s entry into the state of Ohio and the first project delivered in partnership with Trane. Both milestones reflect the growing reach of groundwater geothermal across new geographies and new partnerships, as well as the increasing recognition among facility owners and mechanical contractors that Darcy’s compact, high-capacity well systems offer a practical path to decarbonizing buildings that were never designed with geothermal in mind.
For Union County, the result is a modernized facility with a heating and cooling system built to last, backed by the combined expertise of Darcy, Trane, and Moody’s of Dayton.