I am considering a geo system and am wondering if anyone out there has installed a pump and dump system using water from an existing well?  I have a 3000 sq ft home in Michigan and am looking at retrofitting a 5 ton split system into my existing propane forced air furnaces.  Any info is greatly appreciated!

MJ

Water Quality, Water Quality, Water Quality. Water Quality is the key to an open loop system, I'd say 90 to 95% of the country doesn't have the right water to use a open loop system.  First you need to get your water tested and compare that to the manufacture's recommentation weather the water is pure enough to use.  Just because it's drinkable and don't rot your insides out, doesn't mean the Geo system will not have issues with it.  If the water has too many impurities or the wrong kind of impurities it will clog up the system leading to increase maintanence costs and early failure of the system. Do you know other people in your area that have Open loop systems?
    

Heating (your primary concern) won't produce nearly the deposits that cooling will. Also depends on how comfortable you are with cleaning the heat exchanger. So there is not an exact cutoff point.

We plan on doing a water test soon... What should I look for in the results? Whats good and whats bad?

You are in my AO and I can work most with anything but bacterial iron.
Joe