I recently puchased a HUD home where they winterized the water system. The gas company came out to activate my service, but would not light the water heater pilot because the water system had been winterized. He suggested calling a plumber to drain the hot water heater. Is it necessary to do this or can I simply run the hot water for a while to flush it out, like I did with the sinks, tubs, toilets? If I have to, how would I go about draining the water heater?