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MJD Mechanical geothermal installation FAQ

What type of ground loop should I use?

Answer:

There are many different options for loop fields. They include open/closed, verticle/horizontal, and earthloop/waterloop.

An open loop or 'pump and dump' system works best when there is a free, abundant water supply available such as a water well (providing at least 9 gallons/min), lake or river. A pump and dump works exactly as the name imply's. It pumps water into the geothermal unit, extracts the heat, and dumps the water. Although the capital cost of an open loop can be less than that of closed loop there are some issues that may arise such as:
-environmental by-laws
-water quality/abundance
-heat pump corrosion/scaling
If the water is abundant and of high quality you should give consideration to an open loop design.

A closed loop design is most common in geothermal applications because there is a one time fill and purge on the field. In this case the same fluid is recirculated through the field and back to the heat pump. A closed loop system removes the concern of water supply and quality. It will also help to preserve the life of your geothermal heat pump.

The closed loop system is available in two formats; both horizontal and verticle formats offer consistent, efficient, worry free operation of your system. The verticle loop design uses bore holes 150-180ft deep. This depth increases efficiency because earth temperatures become more stable the deeper you go. The greater efficiency allows the use of less pipe but the cost of installation is greater due to drilling costs. A horizontal system, on the other hand, utilizes a large pit(usually 30ft x 60ft x 6ft deep) in which to bury the pipe. More pipe is needed in this case but the cost of excavation is significantly less than that of drilling.

The final choice is one that most people do not make at all. That is whether your closed, horizontal loop should be installed in a body of water such as a lake or the ocean. The thermal properties of H20 make bodies of water an ideal place to install a geothermal loop field. The advantages of a water loop are:

-no excavation costs
-excellent heat transfer from water to pipe
-ease of installation

Because most property is not waterfront and excavation is cheaper than drilling, the horizontal, closed earthloop is the most popular loop field combination.

M.J.D. Mechanical will visit your site and install the loop best suited for your project.