Hello,
 This post is for feedback about a possible system installment in western Massachusetts.
Due to the location of a new construction, I am forced to install a well for demestic water.  I am currently pricing out a well based open loop system for a 2500 sf house.  There is a good amount of glass in the house with 8 ft ceilings.  For a single heat and cooling system, either Genesis or Tranquility from Climatemaster, what is a realistic price for a system like this.  So far from in information from an installer, i would need 4 ton  for heating and 2 ton for cooling in a two zone system.  It is 2x6 construction with 2x10 floor joists for insulation. There are no high ceilings and a drive under garage.  I image I am leaving out many more variables.

I have done work in construction in other areas, so Geothermal is not familiar to me.  I received a number back from a contractor for a total number to do the whole job of all the instalation of duct work, heat system, and ty in to the well.  What would be a reasonable number for a job like this?  The contractor seemed like a very nace guy and was able to answer some of my questions.  So far, I have not had a person tell me the brake down of the numbers?  So, how much goes into the duct work, how much into the heating system, how much into the water tanks, etc.  I understand like any trade, people are trying to make a living.  I am concerned when people are reluctant to share information about something I will be purchasing.

Also, As a second question, What would be the difference in duct work between a gas/oil forced air system and a geothermal system?

I would appreciate any feedback or information that you can share.  I image there are lots of posts like this one which I will check out. 
Thank you for anyone who responds,
MMB

I'm getting geo this summer for a new 1680 sf house in NH and they sized me at 4 tons.  My house will be energy-star certified and several installers estimated 4 tons, so be sure 4 is sufficient for your 2500 sf house.  Otherwise you will be running backup heat a lot.  I'm getting the Tranquility which is dual stage as opposed to single stage for the Genesis.  My estimate was $24.9K for the combined geo and ductwork (not sure of the split there, but my best seperate ductwork estimate was $9.2K).  The estimate for the well for domestic water plus geo support is $10K.  I've got a couple more estimates coming as well.  Let me know what your estimates are.

I've been told, and it makes sense, that whoever is doing the geo should do the well also, e.g. sub it out.  That way they are responsible for the whole system.  So that's how I'm going.  If you don't do that and your geo does not work properly, the well guy will say the geo unit is undersized, and the geo guy will say the well isn't deep enough.

On the ductwork, I would think the design would be no different for geo than it would for gas/oil.

Where in MA are you?  I lived in E. Longmeadow until last summer. 

I got an estimate to replace my existing open loop geothermal system. It was 8k for the standard 5 ton florida heat pump model and 10k for the top of the line model. This was just replacing the compressor/blower part of the system, the pump and duct work are fine. I didn't have it replaced, I just had my aging system repaired. I'm hoping it clunks along for a few more years.

Just one commet about the duct work, I know the ductwork for Air source heat pumps needs to be bigger than normal, I'm not sure if geothermal has the same requirement.

Typically, duct for any heat pump system ends up being a little bit larger than for gas/oil systems. However, it shouldn't add more than $1,000 in cost, usually, in materials and labor.

With that in mind, you need to know that most geothermal installers are trying to do a quality system. They usually (unfortunately not always) will install duct that's properly sized and designed. This means that there will be a return air connection in every bedroom, along with return air in the common areas of the house. They will use fittings that will have less friction loss, etc. Now, to install that kind of duct is going to cost more than what you would usually get from gas installers.

I'm not saying it's always the case, but I have yet to see more than about 5% of gas furnace installers who actually properly size their duct, and worry about their air distribution to each room. I would attribute that to the fact that they don't offer geothermal. Those who don't, in my opinion, don't care about the customer anyway. They're only concerned about getting their "slam bam" installation done.

I'd suggest you investigate the company's practices with duct sizing and installation. I don't know, though, how you'd substantiate their claims, unless you also know about duct design. Does anyone know a good way for the lay person to figure that out?

I just had a thought about duct work. If say your ducts are undersized, is it possible to install a bigger blower to get the system to push / pull more air What about fan inside the ducts to help things along? While this might not be the ideal solution, it would be cheaper than modifying all of the duct work.

TechGromit,

I have lived in homes done this way.  Every time the blower came on I had to turn up the TV.  What I have found over the years is that few HVAC installers actually do calculations for heat gain/heat loss or duct size.  They use rules of thumb and when they guess wrong they have to turn up the blower to move enough air through too small duct work.

A short answer is this: No.

With too small of duct, the current on the blower motor increases exponentially. It's always far better to re-do duct. Otherwise comfort, and efficiency will never be achieved.

As a general rule, you want to see them deliver 400 cfm of air per ton of system.