[HayZee518]

shut off the electric to the hot water heater or the main gas if it is a gas heater. connect a hose to the boiler drain on the hot water heater and lead it out of the house, then turn on or open the valve. this will be the lowest connection in the house for the hot water supply and will drain by gravity. take the air compressor connection and connect it at the highest hot water out let in the house and open it up. any remaining water in the hot water supply will be forced out at the hot water heater connection's boiler drain and will be blown out of it and the lines. since you have a valve on the cold water supply to the hot water heater, this may prove to be the lowest cold water exit also. once your system is purged of all water by gravity, turn the highest hot water diverter valve to the cold water side and any water left in the cold water will go out the water heater bolier drain.