I am new to this but hope I can get some info from here. I oversee the building and grounds of a large church in Northern Indiana. We are presently getting to replace our air to water chiller with a new unit. The contractor we are working with mentioned going to a new chiller for the high demand cooling load in the summer 120 tons, but in the winter I still need around 28 tons of cooling for our 4 pipe system. We have a 4 acre lake onsite and I am wondering if it would be possible to do a closed pond loop system tied to our outdoor chiller loop (usingt the same pump and gycol) to pull the 28 tons or more needed inthe wintertime for cooling? Any ideas on how to size the loops, or a calculator for this? It would save us a bunch of electricity and demand costs to go this way for the wintertime. Once outside air temp hits a preset, we woould take the pond loop out of the circuit via control valves.