Grainger High School
The entire HVAC system for Grainger High School was designed and installed with energy savings, comfort, health, and longevity in mind.
The new Grainger High School is conditioned with a highly efficient geothermal heating and cooling system. The base building is conditioned by 97 Waterfurnace geothermal heat pumps. Ninty-two of these units are located within the building either in a mechanical room accessible from the hallways or located above the ceiling areas. Five more geothermal units which serve the cafetorium and gymnasium are located on the roof. Fresh air is brought into the building by dedicated rooftop units that are specifically designed for dehumification and energy recovery of exhausted air. These units condition the outside air to 70 degress and 40-50% relative humidity before being distributed to each room in the building.
The geothermal piping which carries the loop water between the borefield and each heat pump is made of high density polyethylene SDR9 pipe. This piping loop ranges in size from 10" diameter to 3/4" diameter. The water is circulated via (2) 50 horsepower Armstrong pumps that are controlled by variable frequency drives. Variable frequency drives save energy as they serve to slow down the loop pumps when individual heat pumps begin to shut down after the room temperature is obtained. Each heat pump is controlled by a Honeywell thermostat which gives each teacher individual room control.
Total Number of Heat Pump Units: 103 Units
- Interior - 92 Units (Waterfurnace Brand)
- Rooftop geothermal - 5 Units (Waterfurnace Brand)
- Rooftop fresh air - 6 Units (Semco and Aaon Brand)
Total Capacity: 403 Tons of total cooling
- Interior Units - 216 Tons
- Rooftop geothermal units - 80 Tons
- Fresh Air Units - 107 Tons
Loop Circulating Pumps: (2) at 50 Horsepower Each with variable frequency drives
Borefield Size: 187 Holes at 450 feet deep each
Typical Loop Water Temperatures
- Summer (60-100 degrees)
- Winter (40-70 degrees)
Total Length of Piping: 176,890 feet
- Interior piping: 4,890 feet
- Borefield (exterior) piping: 72,000 feet
Total Water in Closed Loop: 22,520 Gallons
- Water in borefield: 18,836 Gallons
- Water inside building: 3,684 Gallons