Hellow... anybody out there. I realise now that my original post was kind of vague. I have learned alot in the last few days so let me run this by you. My vertical ground loop has 28 holes at 215 feet each, thats a total bore of 6020feet. The tubing is 1 inch polyethylene on a 2 inch header the grout is non enhanced Bentonite. The guy who drilled the holes gave me a rule of thumb of 200'/ton. My loop pump is 120 Gpm. The caculated tons from 6020 feet of bore hole would be a little little over 30 tons. The system load is 60 tons in cooling and 54 tons in heating. An egineer came along and added a 30 chiller to the 30 ton load of water source heat pumps already in place. I really need to have my ducks in a row on this one. Tuff to argue with an engineer. What am I missing? If we add a bigger pump to the loop then I will be messing with the renolds number thing which I totaly dont get yet. At 3gpm/ton I would need 184 gpm for cooling and 162 for heat. Rather than put in a paralle boiler and cooling tower the best answer may be to dig more holes. I dont know but I am getting a head ache. The ground temperature is 55 degrees in ohio. My little chiller has 2@ 15 ton copeland scrolles and if my water drops below 50 I need to shut one off and then the hot deck has about 85 degree supply. Sorry for the rambling post, I am all wound up on this one. thanks for any insight.