Having already brought up the subject of DX Geo in another thread comparing Geo with the Acadia, I thought I should start another thread before taking my questions any further.

I have a 3,000 sq. ft. Morton pole building with a 12' ceiling.  It is insulated with 6" fiberglass blankets in the walls, and 17" of blown fiberglass in the ceiling.  Inside this building, I am putting an apartment of about 850 sq'.  Two of the outside walls of the building are used by the apartment and the remaining two walls inside will be insulated with 6" fiberglass and the ceiling with 10' of fiberglass.  I also installed 1-1/2" of Foamular Rigid Foam insulation (pink) around the perimeter of the building to a depth of about 16".  This foam is below grade. 

I would like the heat both the building and the apartment, but the building area would be set at around 50 degrees most of the time during the winter unless I am working out there and need to raise it.  I am not particularly concerned about cooling the building but would like to cool the apartment.

Presently, while I am constructing the apartment, I am heating the building with the air handler unit from an old air source heat pump I replaced a number of years ago.  The unit contains the 20 kw backup resistance heat coils from that old heat pump and they easily heat the building to whatever temperature I set it at, although I drop it back to about 48 when I'm not working.

I would like to install a DX geothermal system but would like some input as to the best way to go with this, or even if this is the best way to go.  I am assuming a two-zone system but any other advice or suggestions would be greatly appreciated.  I just recently found a DX dealer within a reasonable distance of my place and will be contacting him shortly to get his input on my idea.  Thanks for you help.      

Thanks for trashing me there
the reality is even a 2 stage unit would have to dump in your situation , The only difference would be they would likely dump back to the return
which which has its unseen drawbacks with heatpumps , or they would ( trust the fan and staging )
and people wonder why there systems are noisy
do ductwork right and dump your zoned systems if you dont you are giving warm air a bad name
I realy hope you dont zone systems with out the use of barometric or preferably an electronic , static pressure operated bypass damper. The only difference between the right way to do what you asked and what Joe is pushing is the amount of air that would get choked/dumped and where it would go chances are it would just temper a room that you keep conditioned anyway

PS I dont sell earthlinked .
If he asked the best way to do a water source unit with 1 system I would have the same recomendation

 if your design cant handle worst case ( smallest zone calling for max ) its not good enough

modern ecm motors factory program 70% W1 80%W2 

If ( and not here ) your zones are close in size you could oversize ducts allow static pressure to bump up because ecms will maintain cfm up to .5 ( which if you get near your doing something wrong) and allow it to drop off when both call . lets now say you have a large difference in zone sizes , the problem is clear pushing 70%  of the air into 25% of the ducts

( which is better then the 80% a single stage unit would push but) your static pressure still goes through the roof and best case you have noisy ducts , worst you go over .5 and your cfm drops allong with your eff. ( number one complaint of warm air systems noise ) 

Which is why we dump , and normally I dont have a problem dumping into the return unless its a large amount of air .

On zoning returns ( I was taught never put any dampers in returns as there is risk and little return ha ) but this is the least of your problems over size the returns so either can fit the needs of the system alone , I would only damper the one in the garage/pole minimize the risk of mod motor failure causing problems