Hot water is coming from 2 cold water taps and one upstairs toilet, turns to cold after 15-20 seconds, it comes out very hot. Thought it might be Bleeding through faucets, so changed laundry tub and kitchen faucett. Still does it. The cold pipes seem to get hot from near the water tank. The dip tube would give the opposite effect? I am fairly handy, but am stumped. The hot water heater( Gas ) was replaced about a year ago, by the gas company. Any ideas?