Hello, I currently have a 3000 sq ft ranch that we purchased 15 years ago. At that time there was a fuel oil hot water boiler used to supply baseboards. I decided about 10 years ago when oil was more expensive and electricity was cheaper to replace the fuel oil with an Argo electric boiler. Made sense at the time, but now the cost is through the roof - used 37,000 kWh in the last year (12 months) in southern OH. There is no ductwork and no central air, just a few room air conditioners. I'm looking at geothermal as a replacement. Ideally I'd like to keep the hot water portion for the winter as it is zoned with separate pumps and valves and works well. I'd like to get A/C as part of the project, but as stated there is no ductwork currently. I tried to see if I could find a multi-split or other system to work with the geothermal and avoid installing ductwork, but I'm having trouble identifying something. Based on relative costs of all of the required components that I'll need and assuming a closed vertical loop, is what I describe above practical or possible? Is there a different path I should consider that is more sensible from an economic standpoint given my constraints? I need to do something this year, and it would be nice to get going considering the cooling season is upon us. Any input to get me going in the right direction is appreciated.

Maybe Chiltrix plus fan coils (retaining your boiler for when it isn't adequate). And reviewing if it makes sense to better insulate and air seal.

If you want to keep your baseboard, you need a high temp water-water heat pump, currently only Waterfurnace makes models which are able to supply water above 140F.
With clever design, you can then send hot water to your domestic hot water tank, and chilled water fem the geo system to a duct system or a wall hang unit for A/C, depending how open your floor plan is.
Just one advise: You are paying a bit of a price right now for falling for a cheaper temporary solution 10 years ago, don't make the same mistake.

Given that you want A/C, the chiltrix fan coils seem like a good idea. Then you can decide whether you want geothermal or just air-source heat pump, which is not quite as efficient but is much cheaper.

But jonr's other advice--to consider the envelope first--makes a lot of sense. I would do the envelope this year, and the heating system next year, because then you can install a smaller, and cheaper heating system.

You're nowhere until you get a handle on the heating & cooling loads.

Got a ZIP code? (For weather data and 99% outside design temp purposes.)

Assuming you burned through 7000kwh/year in non-space heating use (could be more, could be less) you used 30,000 kwh for space heating, which is (x 3412 BTU/kwh) = 102.36 million BTU (MMBTU).

According to degredays.net the southern OH city of Cincinatti went through 4618 heating degree days in the past 12 months (base 65F).

102.36MMBTU/ 4618 HDD= 22165 BTU per degree day, and with 24 hours in a day that's 924 BTU per degree-hour.

The 99% outside design temp in Cinci is +12F ( http://articles.extension.org/sites/default/files/7.%20Outdoor_Design_Conditions_508.pdf ), which is (65F -12F=) 53 F heating degrees below the presumptive balance point.

53F x 924 BTU per degree-hour= 48,972 BTU/hr of implied heat load.

At 16 BTU/hr per square foot of conditioned space actually a bit high for a 3000' house, (VERY high for a tight 2x6 framed house) so there are probably cost effective methods of load reduction that would provide more comfort at a lower cost than extra tonnage of ground source heat pump needed to support the higher load of the house as-is.

That's also WELL above the output capacity of a Chiltrix @ +12F.

There are 4 ton multi-splits that have that much capacity at +12F, but you really need the room by room load numbers to size the heads correctly. Depending on local market there may be a cost-effective GSHP solution too, but you really need to nail down the room/zone loads for the "after" picture of any building envelope upgrades. Find an engineer or RESNET rater (and not an HVAC contractor) to run an aggressive room-by-room load calculation at the 99% & 1% outside design temps, and at 68F indoors (heating) and 80F indoors(cooling), even if you keep it at some other temperature. With those numbers it's possible to reasonably figure out how to do the zoning.

Sorry for the long delay. I had 2 or 3 urgent projects come up that took all my time. I appreciate the thoughtful comments from everyone. I liked the thought of GSHP for a few reasons: 1. significantly lower heating bills 2. hot water discounts 3. not having to deal with room air conditioners every summer 4. baseboard hot water heat is nice but we have a lot of dust in the house - I was hoping that with introduction of duct work we could get some air filtering 5. add value to the house As I see it, the investment in GSHP would be made up of the (vertical) loop, the equipment, and the duct work. If I were to go the mini-split route, the duct work and loop would go away, with maybe a premium on equipment and installation (??) The house (zip 45458) is L-shaped with the main house being 65 years old and an addition which is about 17 years old and is roughly 1/3 of the total house area. The addition is on a slab and has a 13' cathedral ceiling with ceiling fans and is completely open. It has a fireplace that I've been looking to upgrade to high efficiency - we've got enough firewood to last a lifetime. I'm pretty sure there are a lot of envelope efficiency improvements to be made, particularly in the main part. I'm thinking now that running duct work would be very expensive in this arrangement. The attic is unconditioned in the main part of the house (no attic in addition), and the basement is not full. We also know that the well drilling will be a significant expense. With other alternatives available, I'm suspecting that these 2 high ticket parts of the system will never be paid for by the cost savings. I'm still hoping to get some better air cleaning capability, but I'm willing to entertain these alternatives (or a hybrid system of some kind) over a GSHP because I don't think the initial cost is justified. I thank you again and I will have additional questions as I move forward. Thank you again. Marty

A lot of dust in the house is a symptom of high air infiltration rates. A infra-red imaging and blower door guided air sealing effort is going to be "worth it", but you may be able to locate an seal some of the large air leaks before taking it to that point.  Contrary to many peoples' impression, sealing up the house will usually improve the overall indoor air quality, while reducing the dust accumulation.  Only if you're lucky would you be able to seal it up tight enough that active ventilation would be an absolute requirement, but even leaky houses need at least some active ventilation, since the leaks don't always come via the cleanest paths, or supply the air or exhaust where it's needed the most.

The notion that ducted HVAC systems "clean" the air isn't always well founded unless taking it to the HEPA extremes.  The air only circulates when there is a heating or cooling load, and those loads will be smaller once you've dealt with the building envelope issues. You might consider a heat recovery ventilation system using much smaller ducts for improving indoor air quality issues.  (Sometimes that's easy, sometimes not.)  With heat recovery ventilation the incoming air is pre-heated by the exhaust air, which allows high ventilation rates when you want them without adding a huge heating & cooling load.

The 99% outside design temp in Dayton 45458 is +5F, so at a base temp of 65F that's 60 heating degrees.  The past 12 months Dayton had 4691 HDD according to degreedays.net data sets.  Assuming the same 102.36 million BTU from the previous WAG that becomes 22,673 BTU/HDD, or 945 BTU per degree hour, for an implied heat load of ~56,700 BTU/hr.   Rectifiable air leakage could easily be over 10,000 BTU/hr, and taking that load off with air sealing is cheaper than the extra tonnage of heat pump required to support that load.  Getting a 3000' rancher down to 15 BTU/hr per square foot of above-grade conditioned space @ 0F is usually pretty straightforward, which would put you in the  40,000 BTU/hr range @ +5F.

An open hearth fireplace is a major 24/365 infiltration driver.   An air tight wood burning insert or if the firebox of the fireplace is cavernous, a wood stove with a big viewing window is probably going to be worthwhile investment if you burn much wood, since that will improve both indoor and outdoor air quality, and impede a known parasitic loss (the open flue).  When installing the new wood burner take pains to air seal as best you can where the new flue liner enters the flue.  The usually install a metal air barrier with a hole in it to accommodate the liner, but the quality of the air seal is all over the place, and often quite poor unless you impress upon the installer that it's important to you.

The open areas can almost certainly be heated & cooled by ductless air source heat pumps (mini-splits), but you'll need a room-by-room Manual-J to be able to size them correctly, and it's better to have a disinterested third party such as an engineer or RESNET rater run those numbers, not an HVAC contractor.  With the Manual-J in hand you have enough information to vet the sanity of proposals as they come in.