Toyota Park, Bridgeview, IL, USA

Four heating zones

Like the interior of a home or a large office, the field is segmented into four heating zones, also running the length of the field from goal to goal. Each zone contains 42 loops and two temperature sensors that sit within underground boxes connected to one another with plastic conduit. If any underground sensors ever need to be repaired, all eight are on a GPS (Global Positioning System), according to Bennett, enabling service personnel to pinpoint the positions of the underground boxes to within 18 inches. “We also provide a complete photo log of the boxes’ installation, which should also help in locating them,” he says.

On sunny days, the demand for warmth varies from zone to zone, depending on the position of the sun. The sensors in each zone communicate an average demand back to a series of control valves, which modulate the flow of warm water in response. The objective is to keep the root system at a consistently comfortable 65°F, says Bennett. “The field is warm and moist enough that it can actually grow grass in December or even January,” he remarks. “The freezing point for the glycol mixture is minus-25 degrees, so the system can be filled with fluid year-round, without the hassle and expense of draining and re-filling it prior to each season.”