NCARB practice exam- geothermal system questions
See the question below:
The correct answer is vertical closed loop. Why it's not horizontal open loop? Given the condition, I feel this is sufficient while having the lowest cost. Any better explaination?
An architect is specifying a geo-exchange heat pump system for an office building. The building is on a site that has a significant concentration of groundwater and is conducive to well drilling. The owner wants the heat pump system that is the most cost-effective and energy-efficient.
Which heat pump system should the architect specify?
| A. |
Vertical open loop |
| B. |
Vertical closed loop |
| C. |
Horizontal open loop |
| D. |
Horizontal closed loop |
-
The correct answer is B) vertical closed loop. There are a few key factors at play. 1) office building. Unless the question states that there is a lot of land or it is a single family detached house the answer will ALWAYS be vertical loop. There are so many wells for needed and never enough land. 2) Closed loop because you are losing a lot of coolant to the ground. There will have to be significant groundwater to properly exchange heat. additionally you would have to install filters so the lines don't get clogged.
Rules of thumb:
- Single family detached w/ vast, expansive land = horizontal loop
- All commercial, multifamily, single family (little land) = vertical loop
- Never open loop unless one can tap into a significant water source like a lake or aquifer (that will be stated clearly in a question).
- A high water table will never be the deciding factor on open loop or closed loop systems.
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