Mike Lamb Posted May 11, 2013 Report Share Posted May 11, 2013 This is a one bathroom ranch on a slab. This knocking sounds like it is coming from the water heater and only happens when I flush the toilet. It has the same cadence as the ticking on a water meter which is nearby but still it only happens when I flush the toilet and not when I run the other fixtures. https://www.youtube.com/watch?v=WPntL4XrPBI Quote Link to comment Share on other sites More sharing options...
Nolan Kienitz Posted May 11, 2013 Report Share Posted May 11, 2013 Input line to the toilet is possibly from the "hot water circuit". Was the water in the tank warm? I had a new home construction once that had 3/4 of all hot/cold lines reversed and I could have steamed hot dogs in the toilet tanks. Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted May 11, 2013 Report Share Posted May 11, 2013 The little ball in one of the heat traps is hopping up & down. Quote Link to comment Share on other sites More sharing options...
Marc Posted May 11, 2013 Report Share Posted May 11, 2013 These? Marc Quote Link to comment Share on other sites More sharing options...
Mike Lamb Posted May 11, 2013 Author Report Share Posted May 11, 2013 I never knew there is a little ball in there. I thought it was just a cross cut diaphragm at the opening. And it probably has a hot water feed. I never felt the tank. Quote Link to comment Share on other sites More sharing options...
Brandon Whitmore Posted May 11, 2013 Report Share Posted May 11, 2013 So why does the noise only occur when a toilet is flushed, but not when water is run elsewhere? Quote Link to comment Share on other sites More sharing options...
mlparham Posted May 11, 2013 Report Share Posted May 11, 2013 The little ball in one of the heat traps is hopping up & down. What is a residential heat trap? Quote Link to comment Share on other sites More sharing options...
kurt Posted May 12, 2013 Report Share Posted May 12, 2013 It's a dilectric nipple that's got a little marble in it to stop convective flow out of the water heater; it's supposed to reduce heat loss and therefore improve efficiency. Quote Link to comment Share on other sites More sharing options...
Eric B Posted May 12, 2013 Report Share Posted May 12, 2013 It's a dilectric nipple that's got a little marble in it to stop convective flow out of the water heater; it's supposed to reduce heat loss and therefore improve efficiency. Huh? Got a diagram of that? Quote Link to comment Share on other sites More sharing options...
kurt Posted May 12, 2013 Report Share Posted May 12, 2013 Click to Enlarge 35.83 KB Click to Enlarge 35.72 KB Click to Enlarge 32.19 KB There's one's with diaphragms too. Google "heat trap diagrams"; there's about a thousand pics. Quote Link to comment Share on other sites More sharing options...
Mike Lamb Posted May 12, 2013 Author Report Share Posted May 12, 2013 It's a dilectric nipple that's got a little marble in it to stop convective flow out of the water heater; it's supposed to reduce heat loss and therefore improve efficiency. Huh? Got a diagram of that? Click to Enlarge 37.68 KB Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted May 12, 2013 Report Share Posted May 12, 2013 So why does the noise only occur when a toilet is flushed, but not when water is run elsewhere? The alignment of the stars. The toilet fill valve pulls just enough water to affect the pressure at the heat trap. You probably could reproduce the sound if you messed about with other fixtures long enough. Quote Link to comment Share on other sites More sharing options...
Brandon Whitmore Posted May 12, 2013 Report Share Posted May 12, 2013 Thanks Jim, I had this same issue at my house, and the knocking only occurred when I flushed the hall bathroom toilet. Quote Link to comment Share on other sites More sharing options...
Scottpat Posted May 13, 2013 Report Share Posted May 13, 2013 Humm, I have been needing a idea for some new plumbing questions on the NHIE! We have a question writing session soon. Quote Link to comment Share on other sites More sharing options...
John Kogel Posted May 14, 2013 Report Share Posted May 14, 2013 Humm, I have been needing a idea for some new plumbing questions on the NHIE! We have a question writing session soon. That IMO is a pretty tough question to be putting on an exam, considering that many of us have never and may never encounter one of those gizmos in our entire careers. However, if it is one of those choose the best answer out of 4 questions, some of us could guess or deduce the right answer. Maybe that makes it a good exam question. Quote Link to comment Share on other sites More sharing options...
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