New Zealand Plumbers, Drainlayers & Gasfitters
Association Inc
Latest News / Tech Top Tip (Newsflush, July 2015)
Tech Top Tip (aka Technical or Topical Tip) involves a member from the Exec offering his thought, opinion, view, comment on any technical or topical issue relating to our industry and more importantly relevant to you.
This issue, Ross Collins-Wright offers some insight about a mystery banging sound in a hot water pipe that he dealt with recently.
Just recently we had been called to a property where the hot water piping was making a banging sound. This is a mains pressure gas storage water heater, and it was making a loud clicking sound.
Our “technician“ visited the site to investigate what the issue might be.
The most frustrating aspect of it was that it didn’t occur when he was there, making it harder to say with certainty what the problem was.
Through our collective experiences we could have, and quite rightly, presumed it was associated with the valves around the cylinder itself, or taps which were causing water hammer, or high inlet water pressure (bear in mind that the cylinder is around 20 years old). But replacing these and installing a water hammer arrester did not resolve the issue.
The source of the noise was finally tracked down to the cylinder itself.
There is a lot of information on the web about “noises” from hot water systems. Unfortunately, they describe symptoms and solutions that are found overseas and have little or no relevance to New Zealand conditions. They include draining the cylinder and flushing the sludge build up in the base of the cylinder out.
From further investigations that we have carried out, the particular problem that we encountered was possibly from the anode that has corroded away and has dropped into the cylinder and bangs against the side of the tank when the water is turned off or, the other possibility is the spreader for the cold water inlet has come adrift inside. When the tap is turned off this bangs against the inlet inside the tank.
The only recourse is to replace the cylinder.
Hopefully this information is of benefit to the members who might never come across this particular issue, but might retain this snippet from our experience.
