Contracter recently installed 4 ton Trane (WaterFurnace) geothermal residential heat pump with desuperheater in my home. Have been getting hot water through the cold water fixtures since installation. Contractor utilized my existing Marathon 60 gallon water heater and plumbed according to manufacturer specifications with Geo hot feed line at bottom of tank. Contractor came back and installed beck flow preventer on the cold water in line at top of the tank, hoping to resolve, but still getting hot water through the cold faucets. When the desuperheater is not running cold water flows normally. When the desuperheater is running hot water flows through the cold water lines initially and finally turns cold after about 45 to 60 seconds of flow. The contractor called WaterFurnace and said this was probably due to residual heat transfer where the hot and cold water come in contact and could not be resolved. Does this typically happen with all desuperheater installations? Is there a way to separate the hot water from the cold water? I asked the contractor if adding a second holding tank would improve the problem as I had seen some installations done this way on the Internet. The contractor said WaterFurnace told them it may help a little but would not completely eliminate my problem. I am really getting concerned with Summer temperatures soon approaching thinking I will have no cold water once the heat pump switches to cooling mode. All comments/recommendations are greatly appreciated.