Directional boring has gained in popularity in recent years.  The advantage of a horizontally bored geothermal system is that it is a little bit cheaper than a vertical system and is not as invasive as a horizontal system.  The disadvantage is that the installer cannot judge whether a horizontal system has been properly grouted or what the soil conditions actually are.  There have historically been more problems with leaks in directionally bored systems as well as increased risk that an underground utility was compromised without the installer realizing it.

Horizontal loops can be installed either with straight pipe in a trench or with a slinky arrangement where the pipe circles back on itself repeatedly like a slinky.  Typically, strait pipe systems offer the advantage of being able to conform to any space and are therefore ideal for residential installations where there may be many obstacles such as existing trees.  Strait pipe systems also maximize the pipe used because the heat exchanger piping does not interfere with itself like it does in a slinky system.  Slinky systems typically require more pipe than a horizontal system but are ideal where there is a good location to install a grid type system or when there is a very large system to be installed.

Pond loops are the most efficient type of loops but they are also the trickiest.  It is important that the pond loop installer/designer have the experience necessary to help the homeowner or business owner make sure that the pond loop is right for them.  Done properly a pond loop will work great.  Generally speaking pond loops are put together into what looks like a floating raft and then anchored to the bottom of the pond or lake by blocks.  There are also newer systems such as the Slim Jim that utilize a proprietary panel construction.  Ultimately the key is choosing the system that works best for the individual site.