A friend of mine has water continuously running from the vent line shown in the attached picture. This is in the main water line that runs into the house. We live in Florida. Any idea what the problem is and how to fix? Thanks.
That is a reduced pressure back flow. Look for name and model # and serial #
You can buy a rebuild kit. simple to do if you're handy. just a bunch of o-rings, washers and springs.
tear it apart and put back together in less than an hour.