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Hot water bursts but doesn't appear to be air in line

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?

Re: Hot water bursts but doesn't appear to be air in line

If it appears to be a burst of air, then either it is air or steam, and if it is steam, you have a problem. However, I don't think the issue is with the water heater itself. since you are in a townhouse, I will assume that you have city water and are not on a well.

If you are on city water, then does the city water have a backflow preventer. That is a oneway valve on the meter. It prevents any water that gets into your supply line from backing up back into the city water system. City water systems are adding these to prevent someone who might be using some chemicals on a garden hose sprayer from accidently contaminating the city water system.

If you do have a back flow preventer, do you have an accumulator attached to the input side of your water heater. You should because if you don't and the hot water isn't running and the heater comes on, it will increase the pressure in your pipes as the water tries to expand. Normally this excess pressure will leak out you pressure vent in the top of your water heater.

If you do have an accumulator and it is a non bladder type, then it will have a little valve that puts air into the tank when ever the water level in it gets too high. If this isn't working right, it could introduce too much air and that could be the source of your air.

Your water heater installer should be aware of all these issues and should inspect all these components for you. If your installer is not a qualified plumber, then the company that did the install should send out a qualified plumber to inspect.

Re: Hot water bursts but doesn't appear to be air in line

Water contains air and too high the temperature setting on the WH will force the air out of the water.


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