Top 6 Reasons to Install a Geothermal Vault

Monday, February 27, 2017

Although some may argue against the upfront cost, there are many advantages to the use of geothermal vaults in large commercial projects. It can save both the owner and installer time and money over the long haul.

Here are the top six reasons for using a geothermal valve vault in a commercial loopfield according to Stuart Lyle, Director of Geothermal Sales at ISCO Industries.

Photo courtesy of ISCO Industries.

1 Create More Space

A vault can free up valuable area inside of a mechanical room by greatly reducing the number of pipes entering the building.

By utilizing a vault to create a manifold space outside of the building, the system designer can:

  • Maintain the integrity of the building by reducing the number of cored holes that must be drilled through the wall or foundation
  • Create more space for other system components such as pumps and controls
  • Decrease the loopfield contractor’s time inside of the mechanical room, which helps keep the project on schedule by reducing the need to coordinate work times with other trades

2 Separation of Scopes

Vaults not only serve as a central location for circuit piping, they also provide a clean stopping point for the loopfield contractor until system commissioning takes place. In new construction projects, the geothermal scope is often one of the first to get underway and also one of the first to finish. With a vault, geothermal contractors don’t have to wait on the mechanical contractor to finish their scope.

With a vault acting as a stopping point between the loopfield and building:

  • The loopfield contractor can properly pressure test, flush and purge the system without first having to connect to the interior mechanical piping.
  • With an incorporated bypass valve in the vault, the loopfield can remain separated from the supply-return lines that run back to the mechanical room. This allows the mechanical contractor to proceed with the interior installation without compromising the loopfield after it has already been tested.

3 Facilitate Repair

Another advantage of the separation between loopfield and building can be realized when making repairs to a damaged circuit or while searching for leaks. With the loopfield manifold located in the vault (and not in the building), the loopfield contractor won’t need to access the building’s interior to make repairs.

By having butterfly isolation valves on each circuit along with a building bypass, the loopfield contractor can identify the damage or leak, make the repair and complete the pressure test/flush/purge sequence without stepping foot in the building.

In the event that a leak occurs, the vault also prevents spillage or mess inside of the mechanical room, minimizes disruption of activities within the building, and allows the contractor to conserve antifreeze and rust inhibitors by isolating the problem during repair.


Prefabricated vaults offer the contractor a “plug and play” option. Rather than allocating valuable time and labor to building a manifold on site (often while paying prevailing wages), the loopfield contractor can focus on drilling operations and pipe installation while the vault is being made off-site.

Once the vault is on site and in place, the geothermal installer can easily connect the circuits, then sequentially pressure test/flush/purge the circuits, subfields and entire loopfield to prepare the system for operation.

5 Accommodate Larger Distances from the Building

In some cases, the loopfield can be separated from the building by a large distance (500 ft or more). A vault acts as the central point where the combined flow from the field is collected, and a single pair of (larger) supply-return lines are run from that point back to the building. A relatively narrow trench can be excavated to accommodate those lines. Also, supply-returns can be sized for minimal head loss such that distance from the building to the loopfield is a non-factor.

6 Plan for Future Expansion

In some cases, a loopfield may be installed in multiple phases. A vault can be designed with extra circuits to allow for future expansion. In such cases, loopfield expansion can be completed with minimal disturbance inside of the building.

With the many advantages of using a vault as part of a commercial geothermal loopfield design, the first cost can typically be justified.

About the Author

Stuart Lyle
ISCO Industries

Stuart Lyle serves as geothermal sales director and provides technical support for ISCO’s customer base in the United States and Canada. A 10 year veteran of the geothermal industry, Stuart has served in both operations and sales roles. Before joining ISCO Industries, Stuart served as a project manager for a nationwide geothermal installation company. Prior to entering the civilian workforce, Stuart had a prestigious military career in the 3rd Marine Division where he earned a meritorious promotion to the rank of Sergeant and the Navy and Marines Corps Achievement medal for outstanding performance while serving abroad. After completion of his tour in Afghanistan, Stuart continued his military service in the Georgia Army National Guard while simultaneously earning a BS in Physiology and BA in Criminal Justice from the University of Georgia in 2006.