Open Loop vs. Closed Loop Wells Explained

Mosman Well Works • February 16, 2021

There are two categories of geothermal systems that homeowners must choose for their water wells. They are open loop and closed loop. Both methods have their ups and downs, and variables such as your budget, space, preferences, and amount of water will dictate the most suitable option for you. 


Both these systems depend on the consistent temperature of the earth’s surface as a source of heat in winter and a heat sink in the summertime.


The most apparent difference between open and closed-loop systems is the amount of exposure your water has to the open air. Consult the detailed overview below:

Open Loop Systems:

An open-loop geothermal system transfers clean groundwater from a well or other water sources directly to an indoor geothermal heat pump. When the water leaves the building, it is pumped back to the water well, or drainage ponds located a suitable distance from the initial source.

Advantages of Open Loop Systems

  • Cost-efficient because they require little drilling, trenching, burying complex piping systems
  • Less labor-intensive
  • Easy to troubleshoot and repair equipment

Disadvantages of Open Loop Systems

  • Require a larger than average water reservoir
  • Generate too much thermal energy when working pressure is too high
  • Water and the piping system are exposed to contaminants, and the elements

Closed Loop Geothermal

In closed loop systems, water cycles through extensive underground piping systems to cool or heat your household. The earth’s surface is a constant 55° no matter the temperatures in the air. This allows the ground to regulate indoor heat during winter and acts as a heat sink during summer. 


There are three main categories of closed loop geothermal systems which are:


Horizontal 

The piping is laid horizontally. They take up a lot of space, but they’re easy to install and troubleshoot. 


Slinky 

This design features a variation of horizontal systems laid slinky to reduce the overall length of the trenches where the pipes will be installed.



Vertical 

Rather than laying the pipes horizontally, they are installed vertically for 100 and 400 feet deep in wells and connected by a U-bend at the bottom. The boreholes are filled with grout to give them thermal conductivity.

Pros of Closed Loop System

  • Durable and low maintenance; can last for over 50 years with virtually no servicing
  • Environmentally friendly, as they don’t stir up sediment
  • Don’t take up large space

Cons of Closed Loop System

  • Costly to install
  • Difficult to troubleshoot

Call us at Mosman Well Works for expert advice concerning all your well needs.

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