I had a new hot water heater installed three months ago. After the installation we went through the steps to bleed the air out of the lines and it seemed to be fine. However, since the installation when you turn on any hot water faucet, once the cold water already in the line flows out and the hot water begins there is a burst of what appears to be air. After a few moments it stops. It happens on every facet in the house, ever time you turn it on. I have a three level townhouse and the water heater is located in the basement and my supply lines are PVC. I had the installer come to check it out and he seemed to agree that it doesn't seem to be actual air trapped in the lines and couldn't provide an answer. After checking with their plumbing department they said they needed to research it more and that it could possibly be some type of reaction within the water heater. Has anyone experienced this or have a possible solution?