I see here a lot of helpful advice. I also had a problem that the water heater drain off the pipe. I thought that I will repair it with my own hands. But this problem gave me only big headaches. So, I called the guys that are working with blocked drains. They came in 20-30 minutes and explained to me what the problem was. I remained delighted that they ended the work in one hour. I am happy with the result that the water heater worked usually. It is always better to contact an expert that trying to resolve it by yourself in such cases.