Project Spotlight: Johnson Senior High School, St. Paul, Minnesota

Tenon® Thermaseal® Geothermal Grout

Johnson Senior High School stands in the heart of the Payne-Phalen neighborhood in St. Paul. Established in 1897, it sits in a densely populated neighborhood near the city’s core, making it a candidate for a geothermal well field when it needed a new heating, cooling, and humidity control system. TCC Materials manufactures a geothermal grout that meets the Minnesota Department of Health’s stringent rules – meaning it is safe for contact with potable groundwater.

Tenon Thermaseal Geothermal Grout is a thermally conductive cementitious grout that offers low absorption to prevent contamination and mixing with groundwater aquifers, which are a critical component of geothermal heating and cooling systems. Depending on the size, geothermal systems can consist of dozens of wells in which geothermal grout is installed. A geothermal system consists of three parts:

• Ground loop – piping system and the wells.

• Heat pump/exchanger – moves warm/cold water between the building and the wells

• Distribution system – ductwork inside the building

The geothermal system works because the fluid in the system absorbs the heat from the surrounding earth. This fluid is pumped in pipes to the heat pump located in the building. On the heat pump is a heat exchanger that uses the energy to warm the air that passes through the unit. The heated air circulates through the ductwork in the building. The heat exchanger extracts heat from the air to cool the building. The heat pump moves the hot fluid back into the ground to be cooled and then brings the cool water into the system to cool the building.