Hello, Sorry for the delay in response. Your problem would be hard to diagnose if I am not there but I will try my best to suggest something I could think of that could be the reason why you are having hot water on your cold water faucet. Important thing that you should address first is the hot water supply. You did not specify if you have an electric water heater or a gas fired boiler.In any case, you should have a thermostat and you can set it at a lower temperature.If it is an electric heater, you can trace the circuit breaker and turn it off just to lower the temperature of your hot water supply.If you have a gas boiler, you can turn off the gas supply and the electric power to the boiler as well.After that, one scenario I could think of is the the hot water is so hot that the pressure is rising and going back to the cold water supply that could make your cold faucet run hot. That is if there is no check valve installed before the water heater.Another scenario I could think of is that if your faucet has a sing lever and if it is at the center, it means both the hot and the cold valves are opening and you thought you are opening only the cold part, hence hot water would also flow.I do not think you would have a water tank that is heated except the hot water tank.In some scenario, the cold water line is lying on top of the roof and it is being heated by the sun. In this case, you can try to let the water flow for a minute or two and observe if the water would get cold after a while. if it does, then the water line could just be heated by the sun. if it would continue to be hot, then the first two scenario could be the answer.Let me know what you found out.
I've got some photos of the set up.
Scenarios 2 and 3 do not fit.
Scenario 1 is possible.
What a mess of pipes. I have pictures. I think you will laugh.