The podcast features host John Melvin introducing Craig Fishbach, Heat Pump Product Sales Manager at Daikin Applied. The discussion covers geothermal heating systems fundamentals.
Craig explains that geothermal systems operate similarly to refrigerators — a refrigerator keeps the goods inside cold, but it also has to get rid of heat on the back. The system uses a reversing valve to switch between heating and cooling modes by exchanging heat with a water loop rather than outdoor air.
Three primary loop configurations exist: open loop (pump and dump), closed loop, and hybrid systems. Open loop systems pump groundwater through heat pumps and return it. Closed loop systems circulate water through polyethylene pipe buried vertically or horizontally in the ground. Hybrid systems combine geothermal loops with cooling towers for cooling-dominant buildings.
Vertical systems involve drilling deep boreholes and inserting U-bent polyethylene pipes, then grouting them for thermal conductivity. Horizontal systems use trenches with pipes laid in multiple passes. Vertical installations suit commercial properties with limited land, while horizontal systems require more acreage.
“Three primary loop configurations exist: open loop (pump and dump), closed loop, and hybrid systems.
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Ground thermal conductivity testing involves in-situ testing: drilling a test borehole, inserting piping, circulating heated water for 24-48 hours, and measuring temperature changes to determine soil conductivity values used in design calculations.
Geothermal systems demonstrate 25-35% energy savings compared to conventional chillers and boiler systems. Simple payback typically ranges from 5-10 years, though larger buildings often conduct 20-year life cycle cost analyses. Maintenance costs are approximately one-fourth those of chiller systems since they lack boilers and cooling towers.
Schools represent a major geothermal market. Individual water-to-air heat pumps replace centralized chiller-boiler systems, with units serving classrooms, gymnasiums, and cafeterias. Office buildings benefit from modular installation — heat pumps can be added incrementally as tenants lease space, improving cash flow compared to upfront chiller purchases.
Retrofit applications involve replacing aging fan coil systems and unit ventilators with water-to-air heat pump units. Replacement demand is growing as 25-30 year old systems reach end-of-life. Manufacturers now offer moderately efficient units matching older cabinet dimensions, since higher efficiency models require larger physical space.
Axiom Engineering Group
Axiom Engineering Group
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