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HVAC School - For Techs, By Techs

Sep 19, 2019

In this podcast, Michael Housh joins us to discuss his years of experience with geothermal heat pumps and their special considerations.

"Geothermal" is a rather generic term, similar to how people say "Freon" to refer to any kind of refrigerant. Those heat pumps don't necessarily have to be underground; you can have water-source heat pumps in ponds or wells, and there are also ground-source heat pumps. The ground provides a steady temperature under many conditions, which helps heat pumps work effectively in cold climates. Like other heat pump systems, geothermal pumps come in split or package types. The pump may be either integrated with the equipment or separated from it. When the equipment is separate, multiple units can use the same loop (for example, a 10-ton loop can have five 2-ton units attached).

Michael designs geothermal systems. He uses software to design systems, particularly closed-loop systems, and load calculations play an important part in informing his designs. Many contractors use rules of thumb to help size the loops, but the only way to know what you're doing is to take load calculations, especially on water-source pumps. Undersizing loops can severely reduce the system capacity and make it hard to maintain temperature.

To keep performance up, we also need to flush heat exchangers as part of regular maintenance. However, restrictions and contamination tend to be relatively uncommon except in pump-and-dump systems. As with any type of equipment, be sure to follow the manufacturer's recommendations.

Michael and Bryan also discuss:

  • Patience and caring about outcomes of jobs
  • Water temperature and quality effects on system operation
  • Environmental concerns
  • Maximizing efficiency in geothermal systems
  • Geothermal sales and economic trends
  • Return configuration
  • Sharing loops
  • Figuring out gallons per minute and delta T
  • Pump-and-dump configuration
  • Clogged heat exchanger symptoms
  • Identifying problem areas
  • Loop temperature variations

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