I just installed a new hot water heater. When I tried to run hot water in my kitchen sink, it ran for a few seconds and then started spitting air and cold water. I thought I would have to run the water to clear the air in the pipes (the hot water has been shut off for several weeks), but the pipes started to make a violent racket, banging so hard that I thought they might break apart. What to do?:eek!

Gas or electric water heater? When you filled your new water heater did you open a hot water faucet to bleed off the air pressure?