If someone has access to the heavy equipment needed to dig the trenches around the yard and has some plumbing experience, do you think this could be a DIY job?

There are opportunities for sweat equity on all the jobs I sell. A handy person can do the plumbing, the digging, maybe the electrical, finish grade and reseed, the sheet metal......so yes it can be done.
Some of the more complicated tasks will be to lay your hands on fusion tools (because I still wouldn't recommend anything but HDPE for the loops) and flush cart as well as the knowledge to operate all the equipment and design a system.
If you are able to lay your hands on a heat pump and do most everything yourself, you could look into geo excavators that will size/install ground loops for you as well as provide flow center, connect to the heat pump and flush the field for you. If you want open loop then it's cheaper/easier to install.
Our company has started a relationship with a do it yourself supply house where folks can select design service to turnkey installation or any thing in between. Just make sure you get good advice based on good numbers....size based on manual J calculation, electrical based on IEC etc.
Good Luck,
J

Anything can be a Do-it-yourself project, but in the geothermal field the odds are stacked against you. It takes a certain level of knowledge and experience to design and install a geothermal system properly. I'm sure anyone off the street could do it, but the risks for costly mistakes are very high. If the system is too small to handle the heating / cooling load, your not going to see the savings your expecting, if it's a closed loops system, if the loops aren't long enough, they are going to freeze as the winter wears on, etc.

Another issue is the fact that you can't buy the geothermal equipment directly, while it's possible to get them from a source like Ebay, conditions of the equipment and warranties are questionable. HVAC venders rarely want to sell directly to customers, they require more hand holding then contractors do and if you screw up the install, it's nothing but bad press for them.

A partial do-it-yourself is proably the most logical choose. It's doesn't take a rocket scientist to dig a hole so wide, so long and so deep.

  

Joe,

Nice marketing move - betcha you'll get a few where the customer wades in, finds matters not to their liking and calls for help...

I won't pretend that I'm dis interested in moving product, but I also would rather have a DIY in my back yard designed properly, with local experience, not designed over the internet by someone with no clue about our weather here. It's good for me sure, but good for GSHP reputation as well.
J

DIY depends highly on the value of "Y" in the equation.

Another factor to consider is making sure you qualify for the 30% tax credit. I don't think that there is anything in the legislation that would prevent the homeowner from doing all the work and still claiming the 30% credit on the components purchased as well as other associated costs but it just might be more difficult to convince an auditor that all the assorted expenses are part of the geothermal heat pump installation if they are not on one packaged bill from the contractor.

The legislation appears a bit vague referring only to "geothermal heat pumps" and does not list ductwork, wells, groundloops, backup coils etc as part of the "heatpump". If you have a picky auditor and he sees a list of expenses that includes items like ductwork and electric coils, like might say you only can deduct 30% of the heatpump unit itself. If all he sees is a contractor's bill for a geothermal heatpump system and the energystar documentation then he has little to question.