Good afternoon all.  I wanted to thank you guys/girls for all your help on deciding to go with Geothermal.  The information on this site is priceless in educating folks about geo and what questions to ask and the demands we should have of contractors.  We signed our contract yesterday (we have a three day rescission period) and I need your advice.  I received 5 bids and I finalized that down to one company here in Southwest Ohio.  Now I have one company talking poo about the other on a variety of issues, but one in particular I need an independent professional opinion.

We are a 4400 sq ft house in Southwest Ohio and just entered contract on on a 5 series WF, NDV64 (dual compressor and variable speed), desuper, intellistart, intellizone, ducting, 105 gallon Marathon WH, with 150ft per well and 5 vertical fields for 750 feet)

I am being told from the company selected that the Limestone shelling here in Southwestern Ohio are as conducive to grouting.   Apparently, they only grout the top 25 feet of each field and use the limestone to back fill the bottom up to 25 feet.  One company is telling me this is fatal error and our selected company who operates in KY and Ohio has never grouted the entire well. I guess Ohio only requires that the top 25 feet be grouted.   I need your help.  Who is right, is this something I need to stop the contract and negotiate over or indeed it is common in this area to not have to worry about bottom to top grout?

I should note the company selected has been doing Geo since 1985 and installs many, many units.  One other company not selected doesn't grout at all?!?!?! And Kentucky not too far south doesn't require grout.

If the bid/agreement states "Loop to be designed and installed according to IGSHPA standards, grouting per code" doesn't necessary tell me this is being done correctly, or is it?

I appreciate all your input.

You must be dealing with Arronco.. They do a lot of installs in the Cincy area, they are competitive using WF because when they drill, they don't grout at all in KY unless the customer demands it and in Ohio they do the minimum code requirement (which has nothing to do with geothermal, but more for protecting the aquifer).
NOT grouting the entire hole is a crap shoot. Geothermal is about two major things, GPM and Delta T. If you don't grout from the bottom up, how can you possibly know if you have good conductive heat transfer with the pipe? Your system will still function and they probably have customers that are saving on their energy bills but are they saving what they could? If you are going to go through time and expense of doing Geothermal in your home and you want to use them, then ask them to grout the entire hole, it should not cost much more and you will have a predictable performing system.....

IGSHPA standards are that the entire hole be grouted with a tremie inserted to the bottom of the borehole and grouted from the bottom to the top

Thanks for the input.  The company indicates that 20% Bentonite produces .42 k (Btu/h-ft-F) and that Limestone produces .08-3.65 k (Btu/h-ft F).  Of course this makes little sense to the common man.  Are they actually saying here that grouting is less efficient than limestone? 

Grout is often less efficient than the surrounding earth as is SDR11 pipe. However an air gap around the loop is the worst conductor ever. I'd be more interested in the rest of the design (load calcs etc.)

Grouting from the bottom up "should" be standard practice nowadays!
Grouting the top 25' is state requirements, and no grout is required in other states.
Here in NJ, we are required to grout every hole drilled from the bottom up with a Tremie pipe to protect the ground water aquifers.
Grouting the boreholes of geothermal loops should be done to gain the best performance possible. I would discuss your grouting options more closely with the contractors and require a full borehole of grout be inserted for performance stand points alone if it's not required for ground water protection already.
Dan