Bought a home in Southern Maryland. On 3 acres just up against creek and 100 yards from the Patuxent river. I know I have water table just 25 feet down. Do I go with vertical loops to get there, or use my 3 acres for horizontal. Current set-up is a 3.5 ton AC Unit for main house (Fan in basement) and a 1.5 ton for the attached in-law apartment (fan in attic). Basement has an oil furnace with 3 zones. Zone A&B go to hot water reheat coils at both fancoil exhaust ends. Zone C of furnace goes to brazed plate heat exchanger which feeds a hot water storage tank. I am in a quandary on whether I keep the furnace for winter aux heat and DHW or just ditch oil outright and go with a DSH and add circuits for electric water heater and aux heat for winters. Any suggestions from mid-atlantic experiences? Best and later, Trent

Horizontal is cheaper to install and gives you similar performance (in general). It is usually not worth it to keep oil as an aux heat. You have to maintain all the equipment, maintain the oil tank, and it makes the integration more complex.
Usually not worth it. Electric is much cleaner (literally!).

My angst is over getting rid of a 3 year old boiler with high efficiency and absolutely warm reliable heat. This is a new purchase, and I am not in it yet, but just did walk through, contract and home inspection. Turning up the heat and feeling "hot" air from diffusers and 130 deg water at faucets is nice. In order to eliminate oil, I need to remove a UST which was installed 10 years ago, add ampacity to cover a DHW heater and aux heat. Fairly rural home with a 400' underground run to a transformer I may need to upgrade has me extremely conflicted. Much of these details I will not be able to figure out until our closing in May, so I am very tentative on everytinhg but for the fact that I am going geothermal. Thanks for your input.....Trent

How many amps do yo have on your house service?

Southern Md is a fairly mild, geo friendly climate. I'll grant the ability of oil to deliver warm air and hot water, but the cost per gallon of heating oil is tightly tied to the cost of Diesel fuel, and neither is going much below $4 anytime soon.

On a straight Btu basis, all but the most expensive electric utilities compare favorably against $4 heating oil, especially after combustion efficiency, need for combustion air, system complexity, and annual maintenance are accounted for.

The combination of a slowly recovering world economy, continuing Indian and Chinese demand, Middle East political instability, and the gradual decline of the Dollar lead me to conclude that it would be imprudent to rely upon expensively imported and trucked propane or heating oil.

Given the mild climate it may be possible to utilize minimal aux strip heat, perhaps just 5 kW. That won't meet total load but is enough to get by on. A heat pump water heater downstream of DSH tank could conserve as well.

If you had natural gas on site, my advice would be completely different.

Not certain what the service to the house is. Did not get that detailed info on the home inspection and was not paying as close attention. I did note that there was a 90 Amp sub-panel for the in-law appartment. Also a sizeable sub-panel that went out to detached garage to support his woodworking shop. I will not have that extensive use of power tools in the garage, so there is some power I can pull back from the garage. My ideal set-up is about what engineer is showing. Use my hot water storage tank for a DSH and add in a heat pump water heater (one primary reason supporting the heat pump water heater was the fact that he had a dehumidifier plugged in in the basement, so I could get dual benefits from the appliance)
-On another note, with current set-upp, there are 2 separate units. No feasible way to connect the home and apartment ductwork. So will that dictate that I have 2 completely separate ground loops and 2 GHP, or can you use the same loop?

You can have a single ground loop and (2) GSHP. The photo below shows this option using a B&D QT-EA flow center using a common loop field and than a set of pumps for each geothermal unit.