our new home is built on a slab with geothermal furnace closed loop heating. We are on a lake. Within a year of construction we noticed lack of airflow on one side of the house and during walkthrough mentioned it to our builder who shrugged it off. After our landscaping went in and we watered frequently we heard sloshing noises coming from bedroom & bath heating vents..then after a spell of really rainy weather the entire houses first floor ductwork filled up with water...starting at the back of the house and finally go to the front where the a/c shut off as it no longer could work properly. builder then sent the people who laid the ductwork and they pumped out over 3000 gallons of water; it didn't affect the bedroom/bath area. that remained closed off with no a/c for 3 months. from Aug to Nov..then another spell of bad weather and same thing happened again. Over the past 2 years the bedroom bath area has been blocked more than open. The geothermal was not installed by the company who sold the unit to our builder, the ductwork was laid by one sub-contractor and plumbing done by another, both of whom had no prior experience with those furnace types. Now we have mold in the ducts, and any type of rain fills up the bath and high water levels on lake fill up the bedroom. Contractor says it is not his fault. But other contractors say the ductwork was laid too low and they didn't seal it well which accounts for the fact that our heat/ac bills are twice what they were in former home which was bigger than this one. Our furnace frequently cycles on/off as company that dug the well wasn't told it was to be for a geo-thermal and therefore re-used the existing tank/pump from our other well. They were still under warranty but not sufficient to handle this furnace. a cold air exchange was originally laid in wrong area during construction and when they re-routed the spot where it was is right where the ducts go to the bedroom /bath area. Now builder says the slab was done right, the ducts were laid right and we don't know how to prove if they are even in the slab or under it. Either way it appears they were put in too low. Builder is very familiar with lake as his daughter lives on it and should have known of fluctuations in water table...we were new to the area and told him our old cottage which was on a crawl and located 15' further back from lake had never had water problems, but shouldn't he have done something, plus furnace people say that part of problem is how much iron in water and it should have been tested; routine when they install but they weren't licensed in MI only in IN so builder used MI sub-contractors who did none of that. It took them months to get it plumbed right. This is a mess; we can't sell it and it looks like we have no recourse but to reroute ductwork up walls and fill in the floors to get rid of the mold and musty odor. Any suggestions on what to do and where to begin? Help!!