How Does Geothermal Heating Work in the Winter Months?

December 30, 2020

Geothermal heating harvests heat to warm your home from a very old and very reliable source: the planet Earth. A geothermal system is basically a heat pump connected to a buried grid of tubing (known as a ground loop) that circulates water-based coolant continuously to extract latent heat present underground. Here are the basic features of the system:

  • In heating mode, the coolant circulating in the ground loop absorbs latent heat from the earth and conveys it to a specialized heat pump located inside the house.
  • The heat pump compressor concentrates harvested heat, then releases it through a coil as a blower disperses the warmth into the home’s ductwork.
  • The result is dependable, economical heating without any combustion of fossil fuels. Only electricity required to run the circulating coolant pumps and the heat pump/blower is consumed.

Warmth from the Cold Earth?

A frequent question about geothermal heating is how the system extracts warmth from the cold earth during a frigid winter. The answer is simple: The earth isn’t really that cold in winter. Once you go deeper than the frost line — here in New Jersey, that’s about 3 feet — the Earth's temperature actually warms. At around 10 feet, it stabilizes at a steady average of 55 degrees throughout the year — in both winter and summer. This all-season warmth provides a constant source of heat energy sufficient to warm a typical residence when harvested by an efficient geothermal heating system.

Loops: Horizontal vs. Vertical

Certain specifics apply to properly sizing a geothermal heating system for optimum and efficient heat harvesting. The size of the buried ground loop must be calculated to harvest enough heat for the heat pump to warm the home. As square footage of living space increases, the size of the ground loop necessarily increases. However, at sites where available space to bury a horizontal ground loop is insufficient, a vertical ground loop can be inserted into a hole drilled much like a water well, extending deep into the earth to absorb heat.

For more about the benefits and technology of geothermal heating systems, contact Aggressive Mechanical Contractors.